Spore-Bearing Vascular Plants and Gymnosperms

1.1. General Framework: Embryophyta and Tracheophyta

Spore-bearing vascular plants and gymnosperms are two large groups of higher plants that in the modern system are considered part of the clade Embryophyta—land plants, or embryophytes. Embryophytes are characterized by multicellular gametangia and sporangia with a sterile jacket, a cuticle, and heteromorphic alternation of generations: a haploid gametophyte and a diploid sporophyte (Judd et al., 2018; Mauseth, 2017). Embryophytes include “mosses” in the broad sense—liverworts, mosses, and hornworts—as well as vascular plants, or Tracheophyta. At the same time, “mosses” do not form a monophyletic group: they are several early-diverging lineages, whereas vascular plants constitute a clade uniting all other land plants (Judd et al., 2018; Doyle, 2013).

Vascular plants, or Tracheophyta, are characterized primarily by specialized vascular tissues—xylem and phloem. Xylem transports water and minerals, phloem transports organic substances. The water-conducting elements of xylem are tracheids, and in the most advanced groups also vessels; this is why in the Russian-language tradition the whole group is called “vascular plants,” although true vessels are not present in all its representatives (Judd et al., 2018; Evert and Eichhorn, 2013). In addition, vascular plants are characterized by dominance of the sporophyte in the life cycle, the ability of the sporophyte to branch, the presence of numerous sporangia, and, as a rule, differentiation of the body into root, stem, and leaves (Mauseth, 2017; Evert and Eichhorn, 2013).

Within Tracheophyta, two large lineages are distinguished: lycophytes, or Lycopodiophyta, and euphyllophytes, or Euphyllophyta. Lycophytes include modern club mosses, Selaginella, and quillworts. Euphyllophytes include two main groups: monilophytes, or Monilophyta—ferns in the broad sense, including horsetails, whisk ferns, adder’s-tongue ferns, marattioid ferns, and leptosporangiate ferns—and lignophytes, or Lignophyta—woody plants, which include extinct progymnosperms and all seed plants (Doyle, 2013; Judd et al., 2018). Thus, spore-bearing vascular plants do not form a single monophyletic group: they are an evolutionary level, or grade, uniting lycophytes and monilophytes, whereas seed plants arose from one of the branches of euphyllophytes (Judd et al., 2018; Doyle, 2013).

1.2. Spore-Bearing Vascular Plants: Definition and Composition

In educational and agronomic literature, spore-bearing vascular plants are usually understood as vascular plants that reproduce and disperse by spores rather than seeds. These include lycophytes and monilophytes. In the modern phylogenetic system, this group is not a taxon in the strict sense, because it is paraphyletic: seed plants arose from one of the branches of euphyllophytes; therefore, “spore-bearing vascular plants” is a convenient designation for several successive branches that retained spore reproduction (Judd et al., 2018; Mauseth, 2017).

Lycophytes, or Lycopodiophyta, are represented by three modern families: Lycopodiaceae—club moss family, Selaginellaceae—Selaginella family, and Isoetaceae—quillwort family. Lycophytes are characterized by microphylls—small leaves with a single unbranched vein, lateral arrangement of sporangia, and, in some groups, heterospory, i.e., production of microspores and megaspores. Modern club mosses are perennial herbaceous plants, often with creeping shoots and dichotomous branching; Selaginella and quillworts include heterosporous forms (Judd et al., 2018; Mauseth, 2017; Korovkin, 2023).

Monilophytes, or Monilophyta, are a clade uniting horsetails, whisk ferns, adder’s-tongue ferns, marattioid ferns, and leptosporangiate ferns. For most monilophytes, large leaves—megaphylls, or euphylls—with a branching vein system are characteristic. Horsetails, or Equisetaceae, have jointed shoots, whorled reduced leaves, and sporangiophores gathered into strobili. Ferns in the narrow sense, or leptosporangiate ferns, have sporangia with a single-layer wall and usually gathered into sori; among them there are both homosporous and heterosporous forms (Schneider, 2013; Judd et al., 2018; Testo and Sundue, 2016).

Spore-bearing vascular plants have a life cycle with alternation of heteromorphic generations. The sporophyte dominates, while the gametophyte in most groups is free-living, although significantly smaller. In homosporous ferns, the gametophyte is often heart-shaped and photosynthetic; in some groups it may be subterranean and mycotrophic. Fertilization requires free liquid water, because male gametes—spermatozoids—are motile (Mauseth, 2017; Evert and Eichhorn, 2013). In some ferns, long-lived gametophytes are known that can exist without forming a sporophyte, demonstrating the evolutionary plasticity of this group (Pinson et al., 2017).

1.3. Gymnosperms: Definition and Composition

Gymnosperms, or Gymnospermae in the traditional broad sense, are seed plants in which ovules are not enclosed in an ovary and, consequently, seeds are not surrounded by a true fruit. Ovules are located openly on megasporophylls or similar structures; after fertilization they develop into seeds, which may be covered by cone scales or other formations, but not by carpels (Stevenson, 2013; Judd et al., 2018). This is why gymnosperms are called “naked-seeded”: the seed is “naked,” not enclosed in a fruit.

Modern gymnosperms are represented by four main lineages: cycads, or Cycadophyta; ginkgos, or Ginkgophyta; conifers, or Pinophyta; and gnetophytes, or Gnetophyta. Sometimes conifers are considered in the broad sense, including all modern conifer families, and gnetophytes as a separate lineage close to conifers according to molecular data (Stevenson, 2013; Yang et al., 2024). Modern gymnosperms probably form a monophyletic group—Acrogymnospermae, which is sister to angiosperms. However, if extinct forms are taken into account, “gymnosperms” as a traditional group prove to be paraphyletic, because angiosperms originated from one of the branches of seed plants (Judd et al., 2018; Doyle, 2013; Yang et al., 2024).

Phylogenetic relationships within modern gymnosperms remained disputed for a long time. Modern phylogenomic studies show that cycads and ginkgos form a clade sister to the remaining gymnosperms, while gnetophytes are probably nested within conifers—as a sister group either to Pinaceae or to Cupressophyta. These alternative hypotheses are known as “gnepine” and “gnecup” (Yang et al., 2024; De La Torre et al., 2020). For the agronomic context, it is important that conifers in the traditional understanding may prove paraphyletic relative to gnetophytes, if gnetophytes are indeed nested within conifers (Yang et al., 2024).

The key evolutionary acquisition of gymnosperms is the seed. A seed consists of an embryo, storage tissue, and seed coat; before fertilization, the corresponding organ is called an ovule. Unlike spore-bearing plants, in gymnosperms the megaspore does not leave the megasporangium, the female gametophyte develops inside the ovule, and after fertilization a seed is formed (Beck, 2010; Hartmann et al., 2014; Sondervan et al., 2025). In most gymnosperms, the female gametophyte forms archegonia, although in Gnetum and Welwitschia archegonia are absent. In cycads and Ginkgo, motile spermatozoids are retained, whereas in conifers and gnetophytes male gametes are immobile and are delivered to the egg by a pollen tube (Stevenson, 2013; Offer et al., 2023).

1.4. Differences from Mosses

Mosses, or bryophytes in the broad sense, differ fundamentally from vascular plants in the ratio of generations. In mosses, the gametophyte dominates—the green, photosynthetic plant that we usually call a “moss.” The sporophyte in mosses is unbranched, bears a single sporangium, and remains attached to the gametophyte, receiving nutrients from it. True vascular tissues—xylem and phloem—are absent in mosses; some mosses have hydroids and leptoids, similar in function but not homologous to the xylem and phloem of vascular plants (Mauseth, 2017; Judd et al., 2018).

In vascular plants, by contrast, the sporophyte dominates. It branches, bears numerous sporangia, has true xylem and phloem with lignified walls, and is often differentiated into root, stem, and leaves. The gametophyte in spore-bearing vascular plants is still free-living, but in seed plants it is completely dependent on the sporophyte (Mauseth, 2017; Evert and Eichhorn, 2013). It was precisely the transition to sporophyte dominance and the appearance of vascular tissues that allowed vascular plants to reach large sizes and colonize drier habitats than mosses (Judd et al., 2018).

1.5. Differences from Angiosperms

Angiosperms, or Angiospermae, are seed plants in which ovules are enclosed in an ovary formed by carpels, and seeds develop inside a fruit. They are characterized by a flower, stigma, double fertilization and triploid endosperm, as well as maximally reduced gametophytes: the male—pollen grain, the female—embryo sac. The conducting system of angiosperms usually includes true vessels in the xylem and sieve tubes with companion cells in the phloem (Judd et al., 2018; Mauseth, 2017).

Gymnosperms differ from angiosperms by the absence of a flower and fruit, the open position of ovules, the absence of a stigma, and, as a rule, the absence of double fertilization in the form characteristic of angiosperms. In gymnosperms, pollen reaches the ovule directly or into the pollen chamber, not onto a stigma. The female gametophyte in most gymnosperms contains archegonia; the storage tissue of the seed is haploid endosperm, representing the tissue of the female gametophyte, rather than the triploid product of double fertilization (Stevenson, 2013; Judd et al., 2018; Mauseth, 2017). In cycads and Ginkgo, motile spermatozoids are retained, whereas in conifers and gnetophytes siphonogamy is observed—delivery of immobile sperm by a pollen tube (Offer et al., 2023; Stevenson, 2013).

Spore-bearing vascular plants differ from angiosperms even more radically: they have neither seed, nor flower, nor fruit. Their reproduction is associated with spores and a free-living gametophyte, and fertilization requires water. It is these features that limit their distribution and economic use compared with seed plants (Mauseth, 2017; Evert and Eichhorn, 2013).

2.1. Lycophytes — Lycopodiophyta

Lycophytes are one of the oldest lineages of vascular plants. In the Carboniferous period, among them were giant tree-like forms reaching 30–40 m in height and more than 1 m in diameter, which together with horsetails and ferns formed forests and gave rise to coal deposits (Korovkin, 2023; Mauseth, 2017). Modern lycophytes comprise about 1,200 species united in three families: Lycopodiaceae (club moss family), Selaginellaceae (Selaginella family), and Isoetaceae (quillwort family). Together they represent a clade sister to euphyllophytes, that is, to all other vascular plants (Judd et al., 2018; Doyle, 2013).

Lycophytes are characterized by microphylls—small leaves with a single unbranched vein. Such leaves probably originated from lateral outgrowths of the stem—enations—and are not homologous to the large leaves of euphyllophytes (Mauseth, 2017; Judd et al., 2018). Sporangia in lycophytes are located in leaf axils or on the upper side of leaves, often gathered into strobili. Stems usually branch dichotomously, and roots also branch dichotomously. The conducting system is represented by a protostele—a central cylinder of xylem surrounded by phloem (Judd et al., 2018; Korovkin, 2023).

The family Lycopodiaceae—club mosses—includes about 400 species distributed from the tropics to Arctic regions. These are homosporous plants: all spores are identical and upon germination produce a bisexual gametophyte. Gametophytes may be subterranean, mycotrophic, or semi-subterranean, and their development takes from 3 to 15 years (Mauseth, 2017; Korovkin, 2023). The best-known genera are Lycopodium, Huperzia, and Diphasiastrum. Club mosses often grow in coniferous forests, bogs, and tundras. Club moss spores are rich in fatty oils and were formerly used in pyrotechnics, medicine, and technology (Korovkin, 2023; Yakovlev et al., 2006).

The family Selaginellaceae—Selaginella family—is represented by the single genus Selaginella, numbering about 700 species. These are heterosporous plants: they form microspores and megaspores, from which separate male and female gametophytes develop. The megaspore does not leave the sporangium, and the female gametophyte develops inside it, which represents an important evolutionary step toward seed reproduction (Judd et al., 2018; Mauseth, 2017). Selaginellas are predominantly tropical and subtropical plants, often epiphytes or inhabitants of moist shaded places. Some species, for example Selaginella lepidophylla, are known as “resurrection plants”: they can withstand prolonged drying, curling into a ball, and recover upon moistening (Korovkin, 2023; Yakovlev et al., 2006).

The family Isoetaceae—quillworts—includes the single genus Isoetes with about 150 species. These are heterosporous aquatic or coastal-aquatic plants with a shortened tuberous stem and long awl-shaped leaves. Quillworts are the only modern lycophytes that retain a cambium and the ability for secondary thickening, although in a rudimentary form (Mauseth, 2017; Korovkin, 2023). They inhabit oligotrophic lakes and desalinated shallows, and are often threatened by extinction due to water pollution (Yakovlev et al., 2006).

Lycophytes do not have major economic importance, but they play an important role in ecosystems as components of the ground cover, and some species are used in medicine and ornamental horticulture (Korovkin, 2023; Yakovlev et al., 2006).

2.2. Horsetails — Equisetophyta

Horsetails are an ancient lineage whose flourishing occurred in the Carboniferous period. Fossil calamites reached 20 m in height and, together with tree-like lycophytes and ferns, formed Carboniferous forests (Korovkin, 2023; Mauseth, 2017). In modern flora, horsetails are represented by the single genus Equisetum, numbering about 15–20 species. In some classifications they are treated as a separate division Equisetophyta, in others as part of monilophytes (Judd et al., 2018; Schneider, 2013).

Horsetails are perennial herbaceous plants with jointed shoots consisting of nodes and internodes. Leaves are reduced to scales and gathered in whorls, fused at the bases into a sheath. Photosynthesis is carried out by green stems, whose surface is often covered with silica, giving them rigidity. The underground part is represented by a strongly branched rhizome with adventitious roots; in the nodes of the rhizome, tubers with starch reserves often form (Korovkin, 2023; Yakovlev et al., 2006). The stem has a bundle-type structure, usually with a cavity in the center; the conducting system is represented by an endarch siphonostele or eustele (Mauseth, 2017).

Sporangia in horsetails are located on specialized structures—sporangiophores—gathered into strobili at the tips of shoots. Sporangiophores look like shields on stalks, on the inner side of which sporangia develop. Horsetails are homosporous, but their spores are physiologically different: some produce male gametophytes, others bisexual ones. Spores have elaters—hygroscopic bands capable of twisting and untwisting with changes in humidity, which promotes dispersal of spores in groups (Korovkin, 2023; Mauseth, 2017).

Horsetails are distributed worldwide but prefer moist habitats: meadows, bogs, banks of water bodies, and wet forests. Some species, for example field horsetail (Equisetum arvense), are noxious weeds of fields and pastures. Horsetails are toxic to domestic animals, especially horses, due to their content of alkaloids and glycosides. At the same time, field horsetail is used in scientific medicine as a diuretic, and some species are used in ornamental horticulture (Korovkin, 2023; Yakovlev et al., 2006).

2.3. Ferns — Polypodiophyta

Ferns, or ferns in the broad sense, are the most diverse group of spore-bearing vascular plants. In the modern phylogenetic system they are often considered within monilophytes—a clade including, besides ferns in the narrow sense, also horsetails, whisk ferns, and adder’s-tongue ferns (Schneider, 2013; Judd et al., 2018). Ferns number more than 12,000 species and are distributed from the tropics to temperate and even Arctic latitudes. The greatest diversity is concentrated in moist tropical forests, where many species are epiphytes (Testo and Sundue, 2016; Schneider, 2013).

Ferns are characterized by large leaves—fronds, or megaphylls—which are usually pinnately or multiply pinnately dissected. Young fronds are coiled in a fiddlehead—this is the so-called circinate vernation, or “snail.” Stems in most ferns are represented by rhizomes, often covered with scales or hairs. The conducting system is a siphonostele or dictyostele; leaf gaps often form in the stem (Judd et al., 2018; Mauseth, 2017).

Sporangia in ferns may be located on the lower side of leaves, along the margin, or on specialized fertile leaves. In leptosporangiate ferns, sporangia are gathered into sori, often covered by an indusium—a covering membrane. Sporangia have a single-layer wall and a ring of thick-walled cells—the annulus—which ensures active opening and scattering of spores. Most ferns are homosporous, but among aquatic ferns (Marsileaceae, Salviniaceae) there are heterosporous forms (Schneider, 2013; Judd et al., 2018).

Gametophytes of ferns are usually small heart-shaped or ribbon-like thalli, photosynthetic and free-living. In some epiphytic ferns, gametophytes are capable of prolonged growth and even vegetative reproduction by gemmae, and in some cases they can exist without forming a sporophyte—a phenomenon known as “separation of generations” (Pinson et al., 2017). This indicates the high evolutionary plasticity of ferns.

Ferns play an important role in ecosystems, especially in tropical and subtropical forests, where they can dominate the ground cover or occur as epiphytes. Some species, for example bracken (Pteridium aquilinum), are noxious weeds of pastures and fields; others, for example ostrich fern (Matteuccia struthiopteris), are used as food. Many ferns are ornamental and widely cultivated. At the same time, among ferns there are poisonous and carcinogenic species, which must be taken into account in their economic use (Korovkin, 2023; Yakovlev et al., 2006; Judd et al., 2018).

Thus, spore-bearing vascular plants demonstrate a wide range of morphological and ecological adaptations, but their reproduction remains dependent on water, and their life cycles are slower and more vulnerable than those of seed plants. This limits their economic importance, but does not diminish their role in natural ecosystems and in the scientific understanding of plant evolution.

3.1. Dependence of Reproduction on Free Liquid Water

The key limitation of spore-bearing vascular plants is the dependence of sexual reproduction on the presence of free liquid water. In all spore-bearing vascular plants, male gametes—spermatozoids—are motile and equipped with flagella. To reach the egg, they must swim in an aquatic medium: over the surface of the gametophyte, in a film of water, or in a drop of dew. Without water, fertilization is impossible (Mauseth, 2017; Evert and Eichhorn, 2013). This means that for successful reproduction, spore-bearing plants need at least periodically moist conditions: rain, dew, fog, or proximity to a water body.

For agriculture this creates a fundamental problem. A crop plant must reproduce reliably under controlled conditions, and spore-bearing plants cannot be guaranteed to reproduce without water. Even if adult plants can tolerate drought, their sexual reproduction still requires water. This limits the possibilities of cultivating spore-bearing plants in arid and semi-arid regions, which constitute a significant part of the agrosphere. Seed plants, by contrast, carry out fertilization independently of water: pollen is transferred by wind or animals, and male gametes are delivered to the egg through a pollen tube (Judd et al., 2018; Mauseth, 2017). It was precisely this evolutionary acquisition—siphonogamy—that allowed seed plants to colonize a wide variety of habitats and become the basis of agriculture (Doyle, 2013).

3.2. Slow Growth and Low Productivity

Spore-bearing vascular plants, as a rule, grow more slowly than seed plants and are inferior to them in productivity. This is related to the features of their life cycle and anatomy. In ferns and club mosses, the gametophyte often develops slowly: in some club mosses, from spore germination to gametophyte formation, 3 to 15 years pass (Korovkin, 2023; Mauseth, 2017). Even in ferns, where the gametophyte develops faster, time and the presence of water are required for fertilization and sporophyte formation. As a result, the life cycle of spore-bearing plants is longer and less predictable than that of seed plants, which can pass from seed to seed in one season (Judd et al., 2018; Hartmann et al., 2014).

In addition, spore-bearing plants usually do not form large storage organs that could be used as food or for storage. Ferns have rhizomes rich in starch, but they are small compared with tubers, root crops, or seeds of angiosperms. Horsetails also have small storage tubers. The productivity of spore-bearing plants per unit area is generally lower than that of cultivated seed plants, which makes them less profitable for mass production (Korovkin, 2023; Yakovlev et al., 2006). Even those spore-bearing plants that are used as food, for example bracken, require special processing and cannot compete with cereals, legumes, or root crops in yield and nutritional value (Korovkin, 2023; Judd et al., 2018).

3.3. Absence of Large Storage Organs Suitable for Storage

One of the most important conditions of agriculture is the possibility of long-term storage of the harvest. Seeds of angiosperms and gymnosperms contain reserve nutrients—endosperm, perisperm, or cotyledons—and can be stored for months and years in a dry state. Spores, by contrast, do not contain a significant reserve of nutrients and are not intended for long-term storage. They quickly lose viability, especially under moist conditions, and cannot be used as a food product or as seed material in the sense in which seeds are used (Mauseth, 2017; Hartmann et al., 2014).

Rhizomes of ferns and club mosses can accumulate starch, but they do not have protective coverings allowing them to be stored outside the soil. They quickly spoil, sprout, or rot. Horsetail tubers are also small and unsuitable for long-term storage. Thus, spore-bearing plants do not give humans a convenient, transportable, and long-storable product that could be stored and used in unfavorable seasons. Seeds became the basis of agriculture precisely because they can be stored, transported, and sown at the right time (Hartmann et al., 2014; Judd et al., 2018).

3.4. Difficulties of Cultivation and Breeding

Spore-bearing plants are poorly amenable to cultivation and breeding. Their reproduction by spores requires special conditions: spores must fall into a moist environment, gametophytes must develop, and water is needed for fertilization. This complicates mass propagation and makes it less predictable. In addition, spore-bearing plants often have a long juvenile period: in some club mosses the gametophyte develops for years, and the sporophyte grows slowly. This makes breeding extremely difficult: to develop a new variety, much time and many generations are required (Korovkin, 2023; Mauseth, 2017).

Seed plants, by contrast, reproduce by seeds that can be sown under controlled conditions, and their life cycle can often be shortened to one season. This allows rapid selection and development of new varieties. That is why agriculture focused on angiosperms and, to a lesser extent, on gymnosperms, rather than on spore-bearing plants (Judd et al., 2018; Hartmann et al., 2014).

3.5. Comparison with Seed Plants

Seed plants possess a number of advantages that made them the basis of agriculture:

• Independence of fertilization from water due to the pollen tube (siphonogamy) (Doyle, 2013; Mauseth, 2017).
• The presence of a seed—a compact, protected, and nutrient-rich organ suitable for storage and transport (Hartmann et al., 2014).
• A faster life cycle, especially in annual angiosperms, which allows a harvest within one season (Judd et al., 2018).
• High productivity and diversity of forms suitable for cultivation (Korovkin, 2023; Yakovlev et al., 2006).
• The possibility of breeding and genetic improvement, which has led to the creation of thousands of crop varieties (Hartmann et al., 2014).

Spore-bearing vascular plants do not possess these advantages to a sufficient degree. They remain important components of natural ecosystems, are used as medicinal, ornamental, or food plants, but have not become the basis of agriculture. Their role in the agrosphere is limited: they may be weeds, alternate hosts of pathogens, or sources of biologically active substances, but not the main source of food and raw materials (Korovkin, 2023; Yakovlev et al., 2006; Judd et al., 2018).

Thus, spore-bearing vascular plants did not become the basis of agriculture for a whole series of reasons: dependence of reproduction on water, slow growth, low productivity, absence of large storage organs, and difficulties of cultivation and breeding. Seed plants, by contrast, possess seeds, water-independent fertilization, and a fast life cycle, which made them the basis of modern agriculture.

4.1. Cycads — Cycadophyta

Cycads are an ancient lineage of gymnosperms that appeared in the Carboniferous or Permian period and reached their flourishing in the Mesozoic era. Externally they resemble palms or large ferns: most species have a thick, often unbranched trunk bearing a rosette of large pinnate leaves at the top. Some cycads have a subterranean or tuberous stem. Their leaves are pinnate, rigid, often with prickly petioles; young leaves are coiled like those of ferns (Stevenson, 2013; Korovkin, 2023). This similarity to ferns reflects the ancient origin of the group and retained plesiomorphic features.

Cycads are dioecious plants: male and female reproductive structures develop on different individuals. Male strobili consist of numerous microsporophylls bearing microsporangia; female strobili consist of megasporophylls on which ovules are located. In Cycas, megasporophylls are not gathered into a compact cone but form a loose cluster at the top of the trunk; in Zamiaceae they are gathered into true female cones, sometimes very large—up to 1 m in height and up to 40 kg in mass (Stevenson, 2013; Korovkin, 2023). Fertilization in cycads is carried out by multiflagellate spermatozoids—some of the largest in the plant world, up to 0.35 mm in diameter. Spermatozoids are delivered to the egg by a pollen tube, but then actively swim in the fluid of the micropylar chamber (Offer et al., 2023; Norstog et al., 2004). This unique combination of features—the presence of a pollen tube and motile spermatozoids—is characteristic only of cycads and Ginkgo among modern seed plants (Offer et al., 2023).

Cycad seeds are large, often brightly colored, with a fleshy outer coat (sarcotesta) and a hard inner coat (sclerotesta). They are dispersed by animals—birds, monkeys, rodents—which eat the fleshy coat and carry the seeds (Stevenson, 2013; Korovkin, 2023). However, seeds and vegetative parts of cycads contain toxic compounds—cycasin and macrozamin—which can cause poisoning in animals and humans. These toxins probably evolved as protection against herbivores (Stevenson, 2013; Korovkin, 2023).

Modern cycads number about 300–380 species, united in two families: Cycadaceae (the single genus Cycas) and Zamiaceae (the remaining genera). They are distributed in tropical and subtropical regions of Africa, Asia, Australia, and America. Many species are threatened with extinction due to habitat destruction and slow reproduction (Yang et al., 2024; Stevenson, 2013). The economic importance of cycads is limited: they are used as ornamental plants, and some species serve as a source of starch (sago), which requires special processing to remove toxins (Korovkin, 2023; Yakovlev et al., 2006).

4.2. Ginkgos — Ginkgophyta

Ginkgos are an ancient lineage of gymnosperms known from the Permian period and reaching their flourishing in the Jurassic and Cretaceous periods. In the past, ginkgos were represented by many genera and species distributed throughout the Northern Hemisphere. However, by the present time only one species has survived—Ginkgo biloba, which in the wild occurs only in certain regions of China, but is widely cultivated throughout the world (Yang et al., 2024; Korovkin, 2023). Ginkgo is called a “living fossil,” because its closest relatives died out tens of millions of years ago (Korovkin, 2023; Yakovlev et al., 2006).

Ginkgo biloba is a tall deciduous tree reaching 30–40 m in height and living up to 2,000 years. The leaves are fan-shaped, bilobed, with dichotomous venation, located on long and short shoots. Ginkgo is a dioecious plant: male and female reproductive structures develop on different individuals. Male strobili are catkin-like, bearing microsporophylls with microsporangia; female structures are a pair of ovules at the end of a stalk, each with a basal collar. Fertilization is carried out by motile spermatozoids, which are delivered to the egg by a pollen tube, but then actively swim in the fluid of the archegonial chamber (Offer et al., 2023; Korovkin, 2023). This brings ginkgo closer to cycads and distinguishes it from conifers and gnetophytes.

Ginkgo seeds are large, with a fleshy outer coat (sarcotesta), which upon ripening acquires an unpleasant odor caused by butyric acid and its derivatives. The inner coat is hard; the embryo is surrounded by haploid female gametophyte tissue, which serves as storage tissue. The seeds are edible after processing, but in large quantities are toxic (Korovkin, 2023; Yakovlev et al., 2006). Ginkgo is widely cultivated as an ornamental plant due to its beautiful crown shape and resistance to urban conditions; male individuals are preferred, since females produce unpleasant-smelling seeds (Korovkin, 2023; Judd et al., 2018). Extracts of ginkgo leaves are used in medicine as agents improving circulation and memory, although their effectiveness remains a subject of debate (Yakovlev et al., 2006).

4.3. Conifers — Pinophyta

Conifers are the most numerous and widespread group of modern gymnosperms. They number about 600–630 species, united in 60–70 genera and 7–8 families. Conifers are distributed throughout the world, but reach their greatest diversity in temperate and boreal regions of the Northern Hemisphere, where they form extensive forests—the taiga. In the Southern Hemisphere, conifers are also represented, especially in Australia, New Zealand, and South America (Judd et al., 2018; Korovkin, 2023). Conifers are woody plants: trees or shrubs, sometimes reaching gigantic sizes. Coast redwood (Sequoia sempervirens) can reach 115 m in height, and giant sequoia (Sequoiadendron giganteum) up to 12 m in trunk diameter. Great Basin bristlecone pine (Pinus longaeva) lives up to 5,000 years (Korovkin, 2023; Judd et al., 2018).

Conifer leaves are usually needle-like or scale-like, rarely broad. They are covered with a thick cuticle, and stomata are sunken in depressions—these are xeromorphic adaptations that reduce evaporation. In most conifers, leaves are perennial, persisting from 2 to 15 years or more. The stem has well-developed secondary xylem, consisting mainly of tracheids; true vessels are absent, except in gnetophytes. Resin ducts are present in the wood, bark, and leaves of many conifers, especially in Pinaceae (Korovkin, 2023; Judd et al., 2018).

The reproductive structures of conifers are male and female cones. Male cones (microstrobili) consist of an axis with numerous microsporophylls bearing microsporangia. Female cones (megastrobili) in most conifers have a complex structure: they consist of an axis bearing bract scales, in the axils of which are seed scales with ovules. In Pinaceae, the bract and seed scales are free; in Cupressaceae they fuse. In Taxaceae, female cones are reduced to a single ovule surrounded by a fleshy aril. Pollination in conifers is carried out by wind; pollen often has air sacs (in Pinaceae), which facilitates its transfer. Fertilization occurs by means of a pollen tube; spermatozoids are immobile—this is siphonogamy (Judd et al., 2018; Simpson, 2010; Korovkin, 2023).

Conifer seeds are usually winged, which promotes their dispersal by wind. In some genera, for example Juniperus, cones become fleshy and brightly colored, and are dispersed by birds and mammals (Korovkin, 2023; Judd et al., 2018). Conifers are the basis of the forest complex: their wood is used in construction, furniture production, paper production, and also as a source of resins, turpentine, and rosin. Many conifers are ornamental plants used in landscape design and shelterbelt afforestation (Korovkin, 2023; Yakovlev et al., 2006; Hartmann et al., 2014).

Among conifers, several large families are distinguished. Pinaceae—pine family—is the largest family, including pine (Pinus), spruce (Picea), fir (Abies), larch (Larix), cedar (Cedrus), hemlock (Tsuga), and Douglas fir (Pseudotsuga). These are predominantly trees of the Northern Hemisphere, often forming forests. Cupressaceae—cypress family—include cypress (Cupressus), juniper (Juniperus), thuja (Thuja), redwood (Sequoia), giant sequoia (Sequoiadendron), bald cypress (Taxodium), and dawn redwood (Metasequoia). They are distributed throughout the world, but especially in temperate and subtropical regions. Taxaceae—yew family—include yew (Taxus), torreya (Torreya), and nutmeg yew (Amentotaxus). In them, female cones are reduced, and seeds are surrounded by a fleshy aril. Araucariaceae—Araucaria family—include Araucaria (Araucaria), Agathis (Agathis), and Wollemia (Wollemia); they are distributed mainly in the Southern Hemisphere. Podocarpaceae—podocarp family—a large family of the Southern Hemisphere, including Podocarpus (Podocarpus), Dacrydium (Dacrydium), and Phyllocladus (Phyllocladus). Sciadopityaceae—the single genus Sciadopitys from Japan (Judd et al., 2018; Korovkin, 2023; Yang et al., 2024).

4.4. Gnetophytes — Gnetophyta

Gnetophytes are a small but morphologically extremely diverse group of gymnosperms, including three genera: Ephedra, Gnetum, and Welwitschia. These genera are so unlike each other that their relationships long remained unclear. However, molecular data convincingly confirm the monophyly of gnetophytes and their closeness to conifers—probably they are nested within conifers as a sister group either to Pinaceae or to Cupressophyta (Yang et al., 2024; De La Torre et al., 2020). Gnetophytes possess a number of features bringing them closer to angiosperms: the presence of vessels in secondary xylem, similarity of strobili to inflorescences, and in Gnetum and Welwitschia—the absence of archegonia. However, these features probably evolved independently of angiosperms (Stevenson, 2013; Yang et al., 2024).

Ephedra, or ephedra, is the most widespread genus of gnetophytes, including about 40–70 species. These are shrubs or small trees growing in arid regions of Eurasia, Africa, North and South America. Leaves in ephedra are reduced to scales; photosynthesis is carried out by green stems. Strobili are gathered in spikes; male ones contain microsporophylls with microsporangia, female ones contain ovules surrounded by fleshy coverings. After fertilization, the coverings become brightly colored and juicy, attracting animal dispersers. Ephedra has long been used in medicine: the alkaloid ephedrine is obtained from it, used as a central nervous system stimulant and a remedy for asthma (Korovkin, 2023; Yakovlev et al., 2006; Stevenson, 2013).

Gnetum is a genus of tropical lianas, less often trees or shrubs, including about 30–35 species. Leaves in Gnetum are broad, leathery, with pinnate venation, resembling the leaves of angiosperms. Strobili are gathered in spike-like or paniculate inflorescences. Seeds are surrounded by two coverings; the outer covering becomes bright red or orange and fleshy, attracting birds and other animals. Some species of Gnetum are used as food: young leaves and strobili are eaten as vegetables, and oil is obtained from the seeds (Korovkin, 2023; Stevenson, 2013).

Welwitschia mirabilis is the only species of the genus Welwitschia, growing in the Namib Desert in southwestern Africa. This amazing plant has a short thick trunk and two huge ribbon-like leaves that grow from the base throughout the life of the plant, reaching 2–3 m in length or more. The leaves split at the ends under the action of wind and sand. Welwitschia is a dioecious plant; male and female strobili develop on different individuals. The plant is adapted to life under conditions of extreme dryness: it absorbs moisture from fog through numerous stomata on the leaves. Welwitschia is a unique object for studying adaptations to extreme conditions (Korovkin, 2023; Yakovlev et al., 2006; Stevenson, 2013).

4.5. Phylogenetic Relationships Between Gymnosperm Lineages

Modern phylogenomic studies based on analysis of a large number of nuclear genes allow reconstruction of evolutionary relationships between the main lineages of gymnosperms. According to these data, cycads and ginkgos form a clade sister to the remaining gymnosperms. Conifers in the traditional understanding prove paraphyletic: Pinaceae is the sister group to the remaining conifers (Cupressophyta), and gnetophytes are nested within conifers—either as a sister group to Pinaceae (the “gnepine” hypothesis) or as a sister group to Cupressophyta (the “gnecup” hypothesis). These alternatives are actively discussed, and no final decision has yet been reached (Yang et al., 2024; De La Torre et al., 2020; Judd et al., 2018).

It is important to note that phylogenetic relationships within gymnosperms are difficult to reconstruct because of the antiquity of the group, long periods of independent evolution, and possible cases of convergence. For example, the similarity between gnetophytes and angiosperms (vessels, similarity of strobili to inflorescences) was long interpreted as evidence of close relationship, but modern data indicate an independent origin of these features (Stevenson, 2013; Yang et al., 2024). Similarly, the similarity between ginkgo and conifers (monopodial branching, pycnoxylic wood) turns out to be the result of parallel evolution, not common origin (Yang et al., 2024; Korovkin, 2023).

For agronomy and systematics, it is important to understand that the traditional groups “gymnosperms” and “conifers” do not always correspond to monophyletic clades. Modern classification strives to reflect phylogeny, therefore it distinguishes Acrogymnospermae as the clade of all modern gymnosperms, and within it—Cycadophyta, Ginkgophyta, Pinophyta (in the broad sense), and Gnetophyta. However, in applied disciplines, convenient traditional names are retained, because they reflect similar biological and economic properties of groups (Judd et al., 2018; Yang et al., 2024).

Thus, gymnosperms represent an ancient and diverse lineage of seed plants, including four modern groups: cycads, ginkgos, conifers, and gnetophytes. Each of these groups possesses unique morphological and ecological features, but all are united by the presence of a seed and the absence of a true fruit. Conifers are the most numerous and economically important group; cycads and ginkgos are ancient relict lineages that retained motile spermatozoids; gnetophytes are a specialized group close to conifers and possessing a number of features bringing them closer to angiosperms. Understanding the evolutionary relationships between these groups is necessary for their systematics, as well as for practical use in forestry, ornamental horticulture, and medicine (Judd et al., 2018; Korovkin, 2023; Yang et al., 2024; Stevenson, 2013).

5.1. Forestry and Agroforestry

Conifers are the basis of the forest complex of many countries. According to Korovkin (2023), conifers occupy about 39% of the world’s forest area and dominate in boreal forests of the Northern Hemisphere. In Russia, conifers account for about 80% of the area of all forest plantations; more than 30% of Russia’s forests are larch forests, about 20% are spruce and pine forests (Korovkin, 2023). Conifer wood is used in construction, furniture production, the pulp and paper industry, and also as a source of resins, turpentine, rosin, and other products (Korovkin, 2023; Yakovlev et al., 2006).

Pine (Pinus) is the largest genus of conifers, including about 100 species. In Russia, the most widespread is Scots pine (Pinus sylvestris)—a light-demanding plant undemanding to soils, up to 30–40 m tall and with a lifespan of up to 300 years. It grows on sands, bogs, in mountains, and forms extensive forests. Pine wood is used in housing construction, shipbuilding, the aviation industry, and furniture production. By tapping the trunk, oleoresin is obtained—a solution of resin in essential oils—from which turpentine and rosin are produced, used in industry and medicine. Vitamin C and conifer extracts are obtained from needles (Korovkin, 2023; Yakovlev et al., 2006).

Siberian pine (Pinus sibirica), often called cedar pine, produces valuable wood and edible seeds—“pine nuts,” rich in oil. Cedar oil is obtained from them, used as food and in technology (Korovkin, 2023; Yakovlev et al., 2006). Spruce (Picea) and fir (Abies) also have important economic significance: their wood is used in construction and the pulp and paper industry, and fir oil, possessing bactericidal properties, is obtained from fir (Korovkin, 2023). Larch (Larix) is distinguished by hard, strong, and water-resistant wood that does not rot in water and is highly valued in construction; larch forests occupy the largest area in Russia among all forest species (Korovkin, 2023). Cedar (Cedrus) is a tall spreading tree with high-quality wood used in construction; some species are cultivated as ornamental plants (Korovkin, 2023).

Agroforestry is a system of management in which woody plants are combined with agricultural crops or animal husbandry. Conifers can be used in agroforestry to create windbreaks, shade, improve microclimate, and increase land productivity. However, their use is limited by slow growth and competitive influence on herbaceous crops (Judd et al., 2018; Hartmann et al., 2014). In regions with a temperate climate, conifers are often used to create forest strips along fields, which reduces soil erosion and improves the water regime (Yakovlev et al., 2006; Korovkin, 2023).

5.2. Shelterbelts and Erosion-Control Plantings

One of the most important agronomic functions of gymnosperms is the creation of protective forest plantings. Conifers, due to their longevity, resistance to unfavorable conditions, and ability to form dense stands, are widely used to protect soils from wind and water erosion, for snow retention, and also to create windbreaks around fields and gardens (Yakovlev et al., 2006; Judd et al., 2018). In arid regions, conifer plantings promote moisture accumulation in the soil, reduce evaporation, and increase the yield of agricultural crops (Korovkin, 2023; Yakovlev et al., 2006).

The role of conifers in protective afforestation is especially great in the steppe and forest-steppe zones, where they are used to create field-protective strips, erosion-control plantings on slopes of ravines and gullies, and also for afforestation of sands. Scots pine, due to its undemanding nature and ability to grow on poor sandy soils, is one of the main species for sand afforestation and the creation of protective plantings (Korovkin, 2023; Yakovlev et al., 2006). Larch is also used for protective plantings due to its rapid growth and resistance to unfavorable conditions (Korovkin, 2023).

5.3. Sources of Biologically Active Substances

Gymnosperms are an important source of biologically active substances used in medicine, pharmacology, and perfumery. Conifers contain essential oils, resins, vitamins, alkaloids, and other compounds with antimicrobial, anti-inflammatory, wound-healing, and stimulating properties (Korovkin, 2023; Yakovlev et al., 2006).

Essential oils used in aromatherapy, perfumery, and medicine are obtained from the needles of pine, spruce, and fir. Fir oil has bactericidal properties and promotes wound healing (Korovkin, 2023). Turpentine and rosin obtained from pine oleoresin are used in industry and medicine (Korovkin, 2023; Yakovlev et al., 2006). Taxol, an antitumor agent used for treating ovarian and breast cancer, is obtained from yew (Taxus). Taxol was first isolated from Pacific yew (Taxus brevifolia) and later found in other yew species. However, the taxol content in plants is very low, and its production requires large amounts of plant raw material, which makes yew a vulnerable species (Yakovlev et al., 2006; Judd et al., 2018).

Ephedra (Ephedra) is a source of the alkaloid ephedrine, used as a central nervous system stimulant, a remedy for asthma, and to raise blood pressure. Ephedrine is contained in various Ephedra species, especially in Ephedra equisetina and Ephedra distachya. At present, ephedrine is obtained mainly synthetically, but Ephedra continues to be used in traditional medicine (Korovkin, 2023; Yakovlev et al., 2006).

Ginkgo (Ginkgo biloba) is a source of extracts used to improve circulation, memory, and attention. Ginkgo leaf extracts contain flavonoids and terpene lactones with antioxidant and vasodilatory properties. Despite their popularity, the effectiveness of these extracts remains a subject of debate (Yakovlev et al., 2006; Judd et al., 2018).

5.4. Ornamental Horticulture and Landscape Design

Gymnosperms are widely used in ornamental horticulture and landscape design. They are valued for the diversity of forms, sizes, needle colors, and also for their ability to remain ornamental throughout the year. Many conifers are evergreen plants, which makes them indispensable for creating winter gardens, rock gardens, hedges, and specimen plantings (Korovkin, 2023; Hartmann et al., 2014).

Among ornamental conifers, various species of spruce, pine, fir, thuja, juniper, and cypress are especially popular. Thuja (Thuja) and juniper (Juniperus) are often used to create hedges due to their dense crown and ability to tolerate pruning. Cypress (Cupressus) and its pyramidal forms are widely cultivated in warm regions as ornamental plants (Korovkin, 2023; Yakovlev et al., 2006). Redwood and giant sequoia are gigantic trees cultivated in parks and botanical gardens as unique objects (Korovkin, 2023).

Cycads (Cycadophyta) are popular ornamental plants of tropical and subtropical regions. Their large pinnate leaves and thick trunks resemble palms, making them striking specimen plants in parks and gardens. Some cycad species are grown in greenhouses and winter gardens in temperate latitudes (Stevenson, 2013; Korovkin, 2023). Ginkgo (Ginkgo biloba) is a popular ornamental tree valued for its beautiful crown shape and bright yellow autumn foliage. Male individuals are preferred for urban plantings, since females produce unpleasant-smelling seeds (Korovkin, 2023; Judd et al., 2018).

Gnetophytes are also used for ornamental purposes: Ephedra as a drought-resistant shrub for rock gardens and rocky gardens; Gnetum as a tropical liana for greenhouses; Welwitschia as a unique plant for botanical gardens (Stevenson, 2013; Korovkin, 2023).

5.5. Harmful Representatives of Gymnosperms

Although gymnosperms are generally useful to humans, among them there are species that can harm agriculture and forestry. This is primarily related to their role as alternate hosts of pathogenic fungi. The best-known example is juniper (Juniperus), which is an alternate host of the rust fungus Gymnosporangium, causing pear and apple rust. The fungus overwinters on juniper, and in spring its spores infect fruit trees, leading to damage to leaves, fruits, and shoots. In areas where juniper grows near fruit orchards, rust can cause significant damage (Korovkin, 2023; Yakovlev et al., 2006). In this regard, spatial isolation of junipers from fruit plantings or removal of infected plants is recommended.

Some conifers can be toxic to domestic animals. For example, yew (Taxus) contains the alkaloid taxine, poisonous to humans and animals. All parts of the plant except the aril are toxic; poisoning can be fatal. For this reason, yew is not recommended for planting near pastures (Korovkin, 2023; Yakovlev et al., 2006). Cycads are also toxic: their seeds and vegetative parts contain cycasin and macrozamin, causing poisoning and liver damage. In regions where cycads are used as food, special processing is required to remove toxins (Stevenson, 2013; Korovkin, 2023).

Some gymnosperms can become invasive species. For example, Scots pine and some other conifers introduced outside their natural range can spread and displace native species. However, this phenomenon is less characteristic of gymnosperms than of angiosperms (Judd et al., 2018; Hartmann et al., 2014).

5.6. Gymnosperms as an Object of Biotechnology and Breeding

Modern agronomy increasingly uses methods of biotechnology and genetics to improve economically valuable properties of gymnosperms. Methods of microclonal propagation, genetic transformation, and marker-assisted selection are being developed. These approaches are especially actively applied to conifers, which have a long life cycle and slow seed reproduction (De La Torre et al., 2020; Hartmann et al., 2014).

Genetic studies of conifers have identified genes responsible for disease resistance, wood quality, growth rate, and adaptation to drought and cold. For example, study of the PDR (pleiotropic drug resistance) gene family has shown their role in protection against pathogens and resistance to stresses. Some conifer genes may be used to improve other crops (De La Torre et al., 2020). Work is underway on sequencing conifer genomes, which opens new possibilities for breeding and biotechnology (De La Torre et al., 2020; Sondervan et al., 2025).

Thus, the modern significance of gymnosperms for agronomy is multifaceted. They are the basis of the forest complex and protective afforestation, a source of wood, resins, biologically active substances, and ornamental plants. At the same time, some gymnosperms can be harmful as alternate hosts of pathogens or toxic plants. Understanding their systematics, biology, and ecology is necessary for rational use and management of these resources in the agrosphere (Judd et al., 2018; Korovkin, 2023; Yakovlev et al., 2006; De La Torre et al., 2020).

6.1. Club Mosses: Medicinal but Poisonous

Club mosses (Lycopodiaceae) are an ancient group of spore-bearing vascular plants, some species of which possess medicinal properties but can simultaneously be poisonous. The spores of common club moss (Lycopodium clavatum) contain up to 50% non-drying oil and have long been used in medicine as baby powder and a coating for pills. In industry they were used in shaped casting for preparing molds (Korovkin, 2023; Yakovlev et al., 2006). Due to their high fat content, club moss spores ignite easily, which made them suitable for pyrotechnic purposes; in the Middle Ages they were used to produce flashes of light, and later in the first photography experiments (Judd et al., 2018; Korovkin, 2023).

However, the club moss plants themselves are poisonous: their tissues contain alkaloids that can cause poisoning in animals. Animals usually do not eat club mosses, but poisoning is possible when forage is scarce. Some species, for example fir clubmoss (Huperzia selago) and interrupted clubmoss (Lycopodium annotinum), were used for dyeing wool, but their use is limited due to toxicity (Korovkin, 2023; Yakovlev et al., 2006). In modern vegetation cover, club mosses do not play a noticeable economic role, but they retain significance as medicinal and ornamental plants, as well as objects of scientific research (Judd et al., 2018; Mauseth, 2017).

6.2. Horsetails: Noxious Weeds and Toxic Plants

Horsetails (Equisetum) are one of the most economically significant groups of spore-bearing vascular plants, but their significance is predominantly negative. Field horsetail (Equisetum arvense) is a noxious, difficult-to-eradicate weed of fields, meadows, and pastures. Its deeply lying, strongly branched rhizomes with tubers allow the plant to spread quickly and regrow after mechanical tillage. Field horsetail infests crops of cereals, row crops, and vegetables, reducing yield and complicating harvesting (Korovkin, 2023; Yakovlev et al., 2006). Marsh horsetail (Equisetum palustre) and water horsetail (Equisetum fluviatile) behave similarly, also being difficult-to-eradicate weeds of waterlogged habitats (Korovkin, 2023).

Horsetails are toxic to domestic animals, especially horses. Their tissues contain alkaloids and glycosides that can cause poisoning, manifested in impaired coordination, depression of the nervous system, and even death of animals. Cattle can also be poisoned by eating large amounts of horsetail in hay (Korovkin, 2023; Yakovlev et al., 2006). In this regard, horsetails are considered an undesirable component of pastures and hayfields.

At the same time, field horsetail is used in scientific medicine as a diuretic. Young vegetative shoots of field horsetail are used in medicine due to their content of silicic acid, flavonoids, and other biologically active substances. Horsetail preparations are used for edema, inflammatory processes of the urinary tract, and also as a hemostatic agent (Korovkin, 2023; Yakovlev et al., 2006). Some horsetail species are used in ornamental horticulture, especially in landscape design near water bodies (Judd et al., 2018). Thus, horsetails are an example of a group in which useful properties are combined with serious harmfulness, requiring a differentiated approach to their use and control.

6.3. Ferns: Edible but Carcinogenic

Ferns (Polypodiophyta) are the most diverse group of spore-bearing vascular plants, among which there are both useful and harmful species. The best-known edible fern is bracken (Pteridium aquilinum). Its young, still unexpanded fronds (the so-called “fiddleheads”) are eaten in a number of East Asian countries, as well as in some regions of Russia. Bracken rhizomes are rich in starch and mucilaginous substances; after special processing they are also used as food. In Japan, Korea, and China, bracken is a traditional food plant (Korovkin, 2023; Yakovlev et al., 2006).

However, bracken contains carcinogenic compounds, in particular ptaquiloside, which can cause tumors in animals and humans with long-term consumption. In addition, bracken contains the enzyme thiaminase, which destroys vitamin B₁, which can lead to avitaminosis in animals feeding on bracken. In this regard, uncontrolled consumption of bracken as food is not recommended, and hay containing bracken can be dangerous for livestock (Korovkin, 2023; Yakovlev et al., 2006). In some countries, for example in Great Britain, bracken is considered an invasive and poisonous plant posing a threat to pastures and forestry (Judd et al., 2018).

Other ferns can also be harmful. For example, ostrich fern (Matteuccia struthiopteris) is edible when young, but contains toxic compounds requiring special processing. Many ferns are toxic to animals and can cause poisoning when eaten (Korovkin, 2023; Yakovlev et al., 2006). Some ferns are noxious weeds, for example bracken, which spreads rapidly in pastures and displaces forage grasses (Korovkin, 2023; Yakovlev et al., 2006).

On the other hand, many ferns are ornamental and widely cultivated as indoor and garden plants. Nephrolepis (Nephrolepis), maidenhair fern (Adiantum), spleenwort (Asplenium), and other genera are popular in landscaping. Some ferns are used in medicine: for example, male fern (Dryopteris filix-mas) was used as an anthelmintic (Korovkin, 2023; Yakovlev et al., 2006). In general, ferns are a group with high potential for use, but requiring caution because many representatives are toxic.

6.4. Cycads: Ornamental but Poisonous

Cycads (Cycadophyta) are an ancient group of gymnosperms, whose representatives are widely used as ornamental plants in tropical and subtropical regions. Their large pinnate leaves and thick trunks give gardens and parks an exotic appearance. Some species, for example sago palm (Cycas revoluta), are cultivated in greenhouses and winter gardens in temperate latitudes (Stevenson, 2013; Korovkin, 2023).

However, cycads are toxic. Their tissues contain cycasin and macrozamin—neurotoxic and carcinogenic compounds that can cause poisoning in animals and humans. The seeds and vegetative parts of plants are especially dangerous. In regions where cycads are used as food (for example, to obtain sago starch), special processing is required to remove toxins. Without such processing, consumption of cycads can lead to severe liver and nervous system damage (Stevenson, 2013; Korovkin, 2023). Cases of mass poisoning among domestic animals, especially dogs that eat cycad seeds, are known (Stevenson, 2013).

Thus, cycads are an example of a group in which ornamental value is combined with serious danger to humans and animals. When growing them, it is necessary to take toxicity into account and limit access of animals and children to the plants.

6.5. Conifers: Basis of the Forest Complex and Alternate Hosts of Rust Fungi

Conifers (Pinophyta) are the most economically important group of gymnosperms. They are the basis of the forest complex, a source of wood, resins, biologically active substances, and ornamental plants. However, some conifers can be harmful as alternate hosts of pathogenic fungi.

The best-known example is juniper (Juniperus), which is an alternate host of the rust fungus Gymnosporangium. This fungus causes pear and apple rust—a dangerous disease of fruit crops. The fungus overwinters on juniper, and in spring its spores infect fruit trees. Damage manifests as bright orange spots on leaves, fruits, and shoots, leading to reduced yield and fruit quality. In areas where juniper grows near fruit orchards, rust can cause significant damage (Korovkin, 2023; Yakovlev et al., 2006). In this regard, spatial isolation of junipers from fruit plantings or removal of infected plants is recommended.

Other conifers can also be alternate hosts of pathogens. For example, pine (Pinus) is an alternate host of the rust fungus Cronartium ribicola, causing white pine blister rust. The fungus infects pine and currant (or gooseberry), causing serious damage to pine trunks and branches (Yakovlev et al., 2006; Judd et al., 2018). Larch (Larix) can be an alternate host of rust affecting birch and other deciduous species. These examples show that conifers can be not only useful but also harmful in agrocenoses, especially when grown together with fruit and berry crops.

Some conifers are toxic to animals. For example, yew (Taxus) contains the alkaloid taxine, poisonous to humans and animals. All parts of the plant except the aril are toxic; poisoning can be fatal. For this reason, yew is not recommended for planting near pastures (Korovkin, 2023; Yakovlev et al., 2006). Cycads are also toxic, as noted above (Stevenson, 2013).

At the same time, conifers are an indispensable basis of forestry, protective afforestation, and ornamental horticulture. Their wood is used in construction, furniture production, paper production, and also as a source of resins, turpentine, and rosin. Many conifers are ornamental plants used in landscape design and shelterbelt afforestation (Korovkin, 2023; Yakovlev et al., 2006; Hartmann et al., 2014).

6.6. Gnetophytes: Medicinal and Ornamental but of Limited Use

Gnetophytes (Gnetophyta) are a small group of gymnosperms including Ephedra (Ephedra), Gnetum (Gnetum), and Welwitschia (Welwitschia). The most economically significant is Ephedra, from which the alkaloid ephedrine is obtained, used in medicine as a central nervous system stimulant, a remedy for asthma, and to raise blood pressure. Ephedrine is contained in various Ephedra species, especially in Ephedra equisetina and Ephedra distachya. At present, ephedrine is obtained mainly synthetically, but Ephedra continues to be used in traditional medicine (Korovkin, 2023; Yakovlev et al., 2006).

Gnetum (Gnetum) is a tropical liana, some species of which are used as food: young leaves and strobili are eaten as vegetables, and oil is obtained from the seeds. However, the economic importance of Gnetum is limited to tropical regions (Stevenson, 2013; Korovkin, 2023). Welwitschia (Welwitschia mirabilis) is a unique plant of the Namib Desert, without direct economic importance, but of great scientific and ornamental interest. It is cultivated in botanical gardens as a rare and unusual object (Korovkin, 2023; Yakovlev et al., 2006).

Among gnetophytes there are no species that could be considered serious pests of agriculture. However, some Ephedra species can be poisonous to animals when eaten in large quantities due to their alkaloid content (Korovkin, 2023; Yakovlev et al., 2006). In general, gnetophytes are a group with limited economic importance, but with high scientific and ornamental potential.

6.7. Summary: Useful and Harmful Properties of Spore-Bearing Plants and Gymnosperms

In summary, several categories of economically important and harmful representatives of spore-bearing vascular plants and gymnosperms can be distinguished:

Useful representatives:

• Medicinal: club mosses (spores), field horsetail, male fern, yew (taxol), Ephedra (ephedrine), ginkgo (leaf extracts).
• Food: bracken (young fronds), Gnetum (leaves and seeds), cycads (sago after processing), Siberian pine (pine nuts).
• Ornamental: ferns (Nephrolepis, Adiantum, Asplenium), cycads, ginkgo, conifers (thuja, juniper, cypress, spruce, pine), Welwitschia.
• Forestry: conifers (pine, spruce, fir, larch, cedar), used for wood, resins, turpentine, rosin.
• Protective: conifers used to create field-protective strips and erosion-control plantings.

Harmful representatives:

• Weedy: field horsetail, marsh horsetail, water horsetail, bracken.
• Poisonous: club mosses (alkaloids), horsetails (alkaloids and glycosides), ferns (ptaquiloside, thiaminase), cycads (cycasin, macrozamin), yew (taxine), Ephedra (alkaloids).
• Pathogens: juniper (alternate host of pear rust), pine (alternate host of currant rust), larch (alternate host of birch rust).

Thus, spore-bearing vascular plants and gymnosperms demonstrate a wide range of economically significant properties—from useful medicinal and food properties to harmful weedy and toxic ones. Their systematics and biology are important for the rational use of useful species and control of harmful ones, as well as for understanding their role in agrocenoses and natural ecosystems (Judd et al., 2018; Korovkin, 2023; Yakovlev et al., 2006; Stevenson, 2013).