Plant Physiology - Musiyenko M.M. 2001

Physiology of Plant Reproduction
The life cycle of various plants and its connection with flowering processes

The lifespan of different plants varies greatly. Some plants live for a short period—just a few weeks, months, or a single year. Alongside these, There are many herbaceous and woody plants with long lifespans (spanning several centuries, or even millennia in the case of the giant sequoia). However, despite such differences in longevity, they share a common feature tied to their developmental patterns: they first form vegetative Organs—leaves, stems, and roots—followed by reproductive organs. The duration of growth varies among different species, just as reproductive organs develop in different ways. Consequently, plants are divided into monocarpic and polycarpic types.

The first group consists of plants that flower only once in their lifetime, regardless of how long it lasts, and die immediately after flowering and fruiting. This group is very diverse and includes both annual and perennial species. It encompasses:

·ephemerals (whose GROWTH AND DEVELOPMENT cycle takes only a few weeks); annual plants (which form vegetative and reproductive organs, fruit, and mature seeds within a single growing season);

·biennial plants (whose life cycle spans two growing seasons, such as onions, beets, carrots, and others);

·perennial plants (characterized by an extended growth period ranging from 8 to 50 years, after which they flower once and then die).

The second group comprises polycarpic (perennial) plants that flower multiple times throughout their lives, sometimes even blooming two to three times a year if mown, as is characteristic of certain grasses. This group includes plants that begin flowering in their 1st year of life (timothy grass, alfalfa), their 2nd year (perennial lupine), their 3rd year (berry bushes), 8–12 years after grafting (such as pears and apples), and finally at 25–30 years of age (maple, oak, etc.).

Fruit-bearing plants fruit depending on their rootstocks. On dwarf rootstocks, all varieties flower and bear fruit earlier. Pears and apples bloom later than stone fruit species. A defining characteristic of this second group of plants is that their vegetative growth is renewed annually.

It is worth noting that these mentioned groups do not cover the entire diversity found in the plant kingdom.

For instance, agricultural production widely utilizes a Classification of plants by development type into spring crops, which yield a harvest when sown in spring; winter crops, sown in autumn; and facultative (winter/spring) crops capable of producing a yield when sown in either autumn or spring.

In crop production, it is standard practice to distinguish phenological phases during which specific morphological structures are formed. For example, in cereal grains, these include emergence, tillering, stem elongation (jointing), heading, flowering, and the grain development stages—milky ripeness, waxy ripeness, and full maturity.

·For annual dicotyledonous plants, key phases typically distinguished are emergence, the appearance of the first pair of leaves, stem branching, the appearance of inflorescences, budding, flowering, fruit and seed set, and their various stages of ripeness.

In the ontogeny of monocarpic plants, researchers distinguish a period of vegetative and generative (reproductive) development, which includes The formation of inflorescences, flowers, and fruits, as well as their maturation period.