Types of ontogeny and life strategies of plants

Annuals (annualls) are plants that complete their full ontogeny from seed to seed within a single growing season (several months or even weeks). After fruiting, the whole plant dies. A characteristic feature is monocarpy (once‑in‑a‑lifetime flowering and fruiting) (Yakovlev et al. 2005).

Depending on flowering time and photoperiod requirements, annuals are subdivided into:

Most field crops and weeds are annuals. Their agronomy aims at creating optimal conditions for growth within one season and preventing seeding of annual weeds (Gatsuk et al. 1980).

Biennials (bienns) are plants whose ontogeny takes two growing seasons. In the first year, they form a leaf rosette and accumulate reserves in the root (carrot, beet) or in the stem (cabbage, root parsley). In the second year (after vernalization), flowering shoots grow from renewal buds, the plant flowers, fruits, and then dies (Stern 2021; Raven et al. 2005).

Thus, biennials are also monocarpic, but their vegetative phase is stretched over two seasons. In agriculture, they are often cultivated as annuals (e.g., root crops are harvested in the first year without letting them flower), while seeds are obtained from mother plants transplanted in the second year.

Perennials are plants that live more than two years and are capable of flowering and fruiting repeatedly over their lifetime (polycarpic perennials) (Gatsuk et al. 1980). Exceptions are the so‑called monocarpic perennials, which flower and fruit only once at the end of their life (e.g., some bamboo species, agave, palms). They have a long vegetative phase followed by a single generative development and death (Yakovlev et al. 2005).

According to the nature of overwintering organs and shoot systems, perennials are divided into:

For the agronomist, perennial grasses are the basis of forage lands (clover, alfalfa, timothy), as well as many fruit and berry crops. Understanding their ontogeny allows proper management of use and renewal of grass stands, pruning and rejuvenation of orchards.

Plant lifespan is closely related to the ecological strategy (CSR theory, see Chapter 4). Annuals are typical ruderals (R-strategists) or stress‑tolerators (S-strategists) in extreme conditions, whereas perennials are often competitors (C-strategists) (Mauseth 2017; Raven et al. 2005).

Physiologically, the transition to flowering in annuals and biennials is often controlled by photoperiodic response and vernalization (Mauseth 2017). In perennial trees, there is a long juvenile (virginal) period — for example, common ash first flowers only at 20‑30 years (Gatsuk et al. 1980). This period is necessary for forming a powerful crown and root system.

For the agronomist, it is important to know that:

In the next subsection we consider classification by growth pattern — monocentric, acropetal and polycentric types, which determine plant architecture and its ability for vegetative spread.

Monocentric type is characterised by the persistence of the main shoot derived from the embryo throughout ontogeny. The shoot system represents a single centre (“monocentre”). Lateral shoots (branches) never reach the power of the main axis and do not replace it (Gatsuk et al. 1980).

This type is characteristic of most trees (especially conifers — spruce, pine, fir), as well as some tap‑rooted herbaceous plants (lupine, red clover, dandelion). In trees, the main trunk forms monopodially and retains its apical bud for many years (Serebryakova et al. 2006).

In monocentric plants, the individual usually does not disintegrate into parts in old age; it dies entirely. Vegetative propagation is either uncharacteristic or weakly expressed (except for root sucker formation in some trees, e.g., aspen). Maintenance of the main shoot ensures a long life span and high competitive ability (Gatsuk et al. 1980).

Acropetal type (from Greek ἄκρος — tip and πέτομαι — to strive) is a growth pattern in which the shoot system forms through successive death of lower parts and upward growth due to new generations of shoots. The term was proposed for grasses and other plants with intercalary growth (Serebryakova et al. 2006).

In grasses (wheat, rye, timothy), the main shoot elongates thanks to intercalary meristems at the bases of internodes. The lower parts of the shoot eventually die, while the upper parts continue growing. Tillering (formation of lateral shoots) occurs from nodes at the base of the shoot, so the tussock or bush as a whole remains “pulled” toward the soil surface (Gatsuk et al. 1980; Serebryakova et al. 2006).

The acropetal type often combines with polycentric features, especially in loose‑tussock grasses. However, in its pure form it describes a growth dynamic in which the plant seems to “step” over the substrate, leaving dead parts behind.

Polycentric type is the most complex and interesting from the perspective of vegetative propagation. It is characterised by the fact that during ontogeny the initial shoot (from seed) sooner or later disintegrates into several more or less independent parts — particules, each having its own growth centre (“polycentre”). As a result, a clone is formed that can occupy a large area (Gatsuk et al. 1980).

The polycentric type is characteristic of many perennial herbs: long‑rhizomatous (couch grass, ground elder, coltsfoot), stolon‑forming (strawberry, creeping bugle), root‑suckering (yellow sow‑thistle, field bindweed), as well as some shrubs that produce root suckers (raspberry, lilac) (Gatsuk et al. 1980; Serebryakova et al. 2006).

The process of disintegration of an individual into particules is called particulation. It can occur either in the first half of ontogeny (in actively vegetatively mobile species) or at the end (in aging shrubs and some herbs). After particulation, filial (daughter) individuals often rejuvenate — i.e., acquire traits of earlier age states (Gatsuk et al. 1980).

Classification by growth pattern is closely related to life strategies:

For the agronomist, understanding the growth pattern is critically important for controlling perennial weeds:

Thus, knowledge of the ontogenetic form allows not just identifying the weed species, but also choosing the optimal suppression strategy. A detailed description of age stages and particulation processes is given in a separate article.

Classic examples of plants with simple sexual ontogeny are:

Among perennials, simple sexual ontogeny is characteristic of many trees with monocentric growth, especially conifers (spruce, pine, fir), which do not produce root suckers. However, they can regenerate by seed, and vegetative propagation (e.g., by layering) is rare in nature and not the main mode (Gatsuk et al. 1980; Serebryakova et al. 2006).

Knowing that a crop or weed has simple ontogeny determines the management strategy:

In contrast, complex (vegetatively mobile) ontogeny (discussed in the next subsection) creates many more problems for the agronomist, as such plants are capable of active clonal spread and regeneration from small fragments of rhizomes or roots.

The central process of complex ontogeny is particulation (from Latin particula — small part). It is the natural disintegration of the mother individual into several more or less independent parts — particules, each possessing its own root system and shoots (Gatsuk et al. 1980; Serebryakova et al. 2006).

Particulation can occur:

Particules are often rejuvenated — i.e., their age state corresponds to earlier ontogenetic stages (virginal rather than senile), ensuring the clone high viability (Gatsuk et al. 1980).

Gatsuk et al. (1980) distinguish three variants of complex ontogeny in polycarpic plants:

White clover (Trifolium repens). A typical vegetatively mobile perennial. Rooting creeping shoots (stolons) give rise to new particules that quickly separate. In a sward, white clover can persist indefinitely through vegetative spread, even if seed renewal is weak (Gatsuk et al. 1980; Serebryakova et al. 2006).

Potato (Solanum tuberosum). Tubers are modified shoots bearing buds (“eyes”). They serve as organs of vegetative propagation and survival over unfavourable periods. In the wild (in Central America), wild potato also forms tubers, allowing the clone to persist year after year. Seed reproduction is used by breeders, but in commercial production vegetative propagation (by tubers) is used (Yakovlev et al. 2005).

Couch grass (Elytrigia repens). One of the most noxious rhizomatous weeds. Its long cord‑like rhizomes bear many buds. Even a small fragment of rhizome (2‑3 cm) with a bud can give rise to a new plant (Gatsuk et al. 1980). When ploughed, rhizomes are cut into pieces, each of which germinates — this is why simple ploughing does not destroy couch grass but rather promotes its propagation.

Complex vegetatively mobile ontogeny creates serious problems in agriculture, but also opens opportunities for vegetative propagation of crops.

Problems (weeds):

Opportunities (crop plants):

Thus, knowledge of ontogeny type (simple vs. complex) is the basis for choosing a management strategy for both crop and weed plants in agrocenoses. Detailed mechanisms of particulation and its regulation are described in a separate article.

Competitor plants are characterised by the following features (Grime 1979, cited in Stern 2021; Mauseth 2017):

Knowing that a species is a C-strategist allows predicting its behaviour in an agrocenosis:

In the following subsections we consider ruderals (R-strategists) and stress‑tolerators (S-strategists), as well as their secondary combinations.

According to CSR theory (Grime 1979, cited in Mauseth 2017; Raven et al. 2005), ruderals are characterised by:

Classic ruderals are typical weeds of disturbed habitats:

Ruderals usually have simple (sexual) ontogeny (see 3.1). Their strategy is aimed at completing the life cycle as quickly as possible with minimal investment in vegetative structure. They often exhibit photoperiodic neutrality or weak photoperiod dependence, allowing them to flower at any day length (Raven et al. 2005).

Ruderals often exhibit heterocarpy or heterospermy — production of different types of seeds. For example, white goosefoot produces three types of seeds: large ones germinating immediately; small ones with long dormancy; and intermediate ones. This provides a bet‑hedging strategy in unpredictable disturbance conditions (Serebryakova et al. 2006; Zotz et al. 2011).

Ruderals are the main group of weeds on arable land. Their features dictate special control measures:

In the next subsection we consider the third primary strategy — stress‑tolerators (S-strategists), as well as transitional types (C-R, C-S, S-R), which are most often encountered in agrocenoses.

Characteristic features of stress‑tolerant species (Grime 1979, cited in Stern 2021; Gatsuk et al. 1980):

Among crop plants, pure S‑strategists are practically absent because breeding aims at high productivity, which contradicts slow growth and tolerance. However, some forage grasses grown on poor soils are close to S‑strategists (e.g., red fescue — Festuca rubra, perennial ryegrass — Lolium perenne under low nitrogen input).

C-R strategists combine high growth rate and competitive ability under moderate stress with rapid seed productivity. These are typical crop plants and weeds on rich but regularly disturbed soils.

Examples: winter wheat, maize, barley, as well as weeds like white goosefoot (Chenopodium album), pigweed (Amaranthus spp.). Fertilisation and irrigation enhance their competitive traits, while mechanical tillage enhances ruderal traits (ability to quickly seed and recover after damage).

C-S strategists are perennial plants capable of dominating under conditions of constant but not too severe stress (e.g., moderate nitrogen deficiency, periodic waterlogging, partial shade). They grow more slowly than pure competitors, but outcompete them under stress factors.

Examples: many forest perennial herbs (ground elder — Aegopodium podagraria, European wild ginger — Asarum europaeum), grasses and legumes on low‑fertility soils (alfalfa under low nitrogen — C‑S rather than C). In agrocenoses, C‑S strategists often become a problem on fallow lands and pastures without fertilisation.

S-R strategists are a paradoxical combination: they grow under stressful conditions (poor soils, drought) yet reproduce quickly by seed and do not invest in perennial structures. These are annual or short‑lived plants of extreme habitats (pioneers on sand dumps, in rock crevices, on solonetz).

Examples: desert and semi‑desert ephemerals; weeds such as field pennycress (Thlaspi arvense), wild radish (Raphanus raphanistrum) on poor soils; salt‑tolerant ruderal species — seepweed (Suaeda spp.), Russian thistle (Salsola tragus). S‑R strategists are the rarest type.

Understanding secondary strategies allows more accurate prediction of plant responses to changes in agrotechnology and proper selection of weed control measures (e.g., on poor soils, provocation methods that exhaust the seed bank of S‑R weeds are more effective; on fertile soils, agrotechniques that suppress C‑R weeds through competitive crops are more effective).

Indeterminate growth type (from Latin in — not and determinare — to limit) is growth in which the main shoot (and often lateral shoots) never ends with an inflorescence or flower. The apical meristem is maintained throughout the growing season, continuously producing new leaves and side shoots. The plant can grow indefinitely (under favourable conditions).

Determinate growth type (from Latin determinare — to limit) is growth in which the main shoot ends with an inflorescence or flower. After that, elongation of the main shoot stops. Vegetative growth continues via lateral shoots, but they may also be limited (Stern 2021; Raven et al. 2005).

In legumes (soybean, pea, bean, lupine):

In tomato (Solanum lycopersicum):

In bean (Phaseolus vulgaris), bush (determinate) and climbing (indeterminate) forms are distinguished, which also determine growing method and ripening time.

Ripening time: determinate varieties are generally earlier maturing, as the transition to flowering and fruiting occurs faster. Indeterminate varieties yield later but can produce over a longer period.

Uniformity of ripening: determinate forms ripen more uniformly, simplifying mechanical harvesting (especially for soybean, pea, tomato).

Agronomy: for indeterminate soybean varieties, desiccation is sometimes needed to accelerate ripening. For indeterminate tomatoes, trellises and pruning are required (Mauseth 2017).

Breeding significance: the shift from indeterminate to determinate growth is often controlled by one or a few genes, making it relatively easy to create varieties with desired architecture (e.g., dt1 gene in soybean, sp (self‑pruning) gene in tomato) (Stern 2021).

Determinate growth is associated with an earlier switch of the apical meristem from the vegetative to the generative state. This switch is regulated by hormonal factors (especially gibberellins and florigen) and is genetically controlled. In determinate forms, expression of flowering genes occurs earlier and at smaller plant size. In indeterminate forms, long vegetative growth is maintained, which is advantageous when large vegetative mass is needed (e.g., for silage) or when the risk of early frosts is low.

For the agronomist, the choice between determinate and indeterminate varieties is a compromise between early maturity and harvest uniformity on one hand, and potential productivity and adaptability to a long season on the other. In the Non‑Black Earth region and Siberia, determinate forms are preferred, whereas in southern regions, indeterminate varieties that provide higher total yield can be successfully grown (Raven et al. 2005).

In the next subsection we consider photoperiodic response — another crucial ontogenetic trait determining crop adaptation to different latitudes.

Depending on the day length that induces flowering, three main groups are distinguished (Raven et al. 2005; Stern 2021):

Photoperiod perception occurs in leaves, not in the apical meristem. In leaves, under the control of phytochrome (and cryptochromes) and circadian rhythms, the protein FT (Florigen) is synthesised, which is transported via phloem to the apical meristem and initiates the transition to flowering (Mauseth 2017; Poethig 2013). A key role is played by the length of the dark period: SDP flower only when the night exceeds a critical length; LDP, conversely, require a short night. A single red light pulse in the middle of a long night can interrupt the dark period and prevent flowering in SDP but promote it in LDP (Raven et al. 2005).

Choice of varieties by photoperiodic sensitivity. When moving a crop to new latitudes, its photoperiodic type must be considered. For example, southern (short‑day) soybean varieties, when grown in the north, may not flower before frost or will flower very late, whereas northern (weakly sensitive or neutral) varieties mature successfully (Raven et al. 2005).

Control of flowering time. In protected cultivation (greenhouses), by regulating lighting one can shift flowering in SDP crops (chrysanthemum, everbearing strawberry) or, conversely, delay it to obtain more vegetative mass (e.g., in lettuce, spinach — LDP plants that bolt quickly under long days).

Breeding for photoperiodic neutrality. Most modern varieties of major agricultural crops (wheat, barley, rice, maize) are neutral or weakly sensitive, allowing them to be grown across a wide range of latitudes (Raven et al. 2005). However, in some cases (e.g., for green mass production of lupine or clover), a long‑day response remains, which must be considered when choosing sowing dates.

Spring forms — complete their life cycle from seed to seed within one growing season. They do not require low‑temperature exposure for flowering; they flower under spring‑summer temperatures and long days (for LDP) or long days (Raven et al. 2005).

Winter forms — in order to flower, they must undergo vernalization — exposure to low positive temperatures (usually 0…+8 °C) for several weeks (Mauseth 2017; Stern 2021). In nature, this occurs during winter. If winter forms are sown in spring, they will not flower that same year but will continue vegetative growth. Therefore, they are sown in autumn; after winter vernalization, they resume growth in spring and flower in summer.

Vernalization is perceived by the apical meristem (unlike photoperiod, which is perceived by leaves). Under cold, expression of the flowering repressor gene FLC (in Arabidopsis and related species) is suppressed in the meristem, allowing activation of florigen under favourable conditions (Mauseth 2017; Poethig 2013). After vernalization, plants become capable of flowering under long days (for typical winter cereals) or under neutral photoperiod. There are also winter forms of biennials (cabbage, carrot, beet), where vernalization is also necessary but flowering occurs in the second year of growth (Stern 2021).

Sowing dates. Winter forms are sown in autumn (in central Russia — August–September) so they can root and tiller before cold weather and then overwinter. Spring forms are sown in early spring.

Winter hardiness. Winter forms undergo hardening in autumn and acquire frost resistance. Spring forms lack this ability; they can only be sown in spring and cannot withstand winter temperatures (Raven et al. 2005).

Breeding. Intermediate (facultative) forms exist that can yield under both autumn and spring sowing. Their creation expands the cultivation area and allows more flexible crop planning.

Practical techniques. In some cases (e.g., growing winter wheat in Siberia), it is important to calculate sowing dates precisely so that plants undergo vernalization but do not freeze. Sowing too early may cause overgrowth and reduced winter hardiness; sowing too late may prevent sufficient tillering and lead to freezing (Stern 2021).

The relationship between vernalization and photoperiodism is illustrated by winter rye: it requires vernalization, but after vernalization, flowering occurs only under long days. Thus, the plant uses two sequential signals: first cold (winter), then long days (spring–summer), ensuring flowering at the optimal time (Mauseth 2017).

For the agronomist, knowledge of photoperiodic response and whether a variety is spring or winter type is the basis for developing variety‑specific agronomy, choosing sowing dates, and selecting crop rotation predecessors. In the next section, we consider how ontogeny and life strategies relate to the production process — yield formation and assimilate distribution in the plant.

Simple (sexual) ontogeny (beet, sunflower, carrot, annual legumes) — characterised, as a rule, by a taproot system. The main root, developed from the embryonic radicle, penetrates deep into the soil and functions throughout life. Lateral roots branch from it, but the main root remains dominant. Such a system provides the plant with access to water from deep horizons, important under dry conditions (Evert 2006; Gatsuk et al. 1980). However, in some crops (e.g., sunflower), under intensive nitrogen nutrition and irrigation, the taproot system may weaken, giving way to a fibrous system (Serebryakova et al. 2006).

Complex (vegetatively mobile) ontogeny (white clover, potato, couch grass) — characterised by a fibrous root system consisting of adventitious roots arising from shoot nodes (rhizomes, stolons, tubers). The main root, if it develops, dies early. Such a system ensures rapid exploitation of the top, most fertile soil layer, but makes the plant dependent on surface moisture (Gatsuk et al. 1980; Serebryakova et al. 2006).

Competitors (C-strategists) — usually form a powerful, deep‑penetrating and highly branched root system, allowing them to intercept resources from neighbours. In competitor trees (oak, beech), roots can go down 5‑10 m or more (Raven et al. 2005).

Ruderals (R-strategists) — have a shallow but fast‑growing root system, often fibrous. They efficiently use short‑term resources but cannot tolerate drought or soil compaction (Mauseth 2017).

Stress‑tolerators (S-strategists) — root systems are often mycorrhizal (especially in Ericaceae, Orchidaceae), enhancing uptake from poor soils. In many S‑strategists (sedges, heather), roots are perennial, tough, slow‑growing (Serebryakova et al. 2006).

When cultivating cereals and row crops, knowledge of root system type allows correct choice of depth and method of primary tillage. For example, crops with a taproot system (sunflower, beet) require deeper ploughing or subsoiling to eliminate plough pans.

For controlling rhizomatous weeds (complex ontogeny), the exhaustion method is effective — repeated shallow cutting of rhizomes, which stimulates bud awakening and depletion of reserves (Gatsuk et al. 1980).

Tap‑rooted perennial weeds (dandelion, wormwood) are easier to destroy by deep cutting of the main root below the root collar (Serebryakova et al. 2006).

Annuals (monocarpics) — allocation shifts strongly toward generative organs after the transition to flowering. Most assimilates are directed to seeds; vegetative organs senesce and die. In cereals (wheat, barley), the harvest index (grain mass to total above‑ground mass ratio) can reach 0.4‑0.5 (Stern 2021).

Perennials (polycarpics) — assimilates are directed both to vegetative growth (especially in trees and shrubs) and to fruit and seed formation. A large part of the carbon is stored in perennial tissues (trunk, roots, rhizomes). In fruit crops (apple, pear), there is periodicity of fruiting associated with alternation of years with high and low allocation to generative organs (Raven et al. 2005).

Ruderals (R-strategists) — maximum allocation to seeds. Vegetative mass is minimal. This ensures rapid reproduction and colonisation of disturbed sites.

Competitors (C-strategists) — a significant portion of assimilates goes to building powerful vegetative structures (trunk, branches, leaf canopy), allowing capture of space and light. Allocation to seeds is lower than in ruderals.

Stress‑tolerators (S-strategists) — assimilates are predominantly stored in perennial storage organs (rhizomes, wood), while height growth and seed production are limited (Grime 1979, cited in Raven et al. 2005; Gatsuk et al. 1980).

To obtain high grain yields (wheat, rice, maize), it is necessary to manage allocation in favour of the ear or cob. This is aided by: optimal plant density, nitrogen top‑dressing at the stem elongation – heading stage, and the use of determinate varieties (Stern 2021).

In forage grasses (clover, alfalfa, timothy), it is important that allocation goes to leaf mass rather than stems. For this, timely cutting at the budding – early flowering stage is used (Serebryakova et al. 2006).

In fruit crops, allocation is regulated by pruning (rejuvenation, crown shaping), fruit thinning, and fertilisation. Pruning stimulates vegetative growth, while limiting fruit set enhances allocation to the remaining fruits (Raven et al. 2005).

Ruderals (R-strategists) — have high “greediness” for fertilisers (especially nitrogen). When nitrogen is applied, they sharply increase vegetative mass, often at the expense of allocation to fruits (luxuriant growth). This property is used in breeding intensive‑type varieties, but also explains the high competitive ability of ruderal weeds on fertilised fields (Mauseth 2017; Stern 2021). Examples: white goosefoot, pigweed.

Competitors (C-strategists) — also respond well to fertilisers, especially phosphorus and potassium, but their response is more balanced: the increase in vegetative mass does not dominate over seed yield as strongly. Typical C‑strategists (perennial grasses) give yield increases with NPK (Serebryakova et al. 2006).

Stress‑tolerators (S-strategists) — responsiveness to fertilisers is weak or absent. Applying fertilisers on poor soils may even depress them by activating competitors. S‑strategists are adapted to low nutrient levels, and increased fertility often leads to their displacement (Raven et al. 2005; Gatsuk et al. 1980). For example, heather on a fertilised plot is quickly replaced by grasses.

Crop varieties bred for intensive technologies are close to R‑ or C‑R‑strategists in their characteristics: they are highly responsive to fertilisers but require protection from pests and diseases because their tissues are less resistant (Stern 2021).

Extensive‑type varieties (drought‑tolerant, salt‑tolerant, short‑statured) exhibit traits of S‑ or S‑R‑strategists: they respond weakly to fertilisers but yield reliably under stress conditions (Raven et al. 2005).

When developing a fertilisation system, the ontogenetic form of the weed must be considered. Rhizomatous weeds (complex ontogeny, C‑ or C‑R‑strategists) respond well to nitrogen, so their suppression requires applying fertilisers as localised side‑dressing (under the crop) and using herbicides (Gatsuk et al. 1980).

Knowledge of the relationship between ontogeny type and life strategy with the production process allows the agronomist to: