BOTANY WITH BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

VIII. BASICS OF PLANT MORPHOLOGY AND ANATOMY

Morphology and Anatomy of the Stem and Shoot

Plant Life Forms

According to their SHOOT types and lifespan, plants are classified into the following life forms: trees, shrubs, subshrubs, dwarf shrubs, and herbs. Trees are large plants with a robust, perennial stem that Supports a crown and is capable of secondary thickening.

A shrub is characterized by the absence of a single dominant main stem in terms of thickness or height, meaning they do not form a distinct crown (e.g., hazel, buckthorn, spindle tree, wild rose, hawthorn). Shrub stems branch right near the ground, producing numerous shoots 2-6 m high. Shrubs whose annual shoots remain above the snow line and die back each year are called half-shrubs (e.g., Russian broom). Shrubs that reach a height of about 1 m are called dwarf shrubs (e.g., blueberry, marsh tea, heather).

Subshrubs are perennial plants whose lower parts are woody and covered with cork, whereas young annual shoots dry out and die off in winter due to frost and harsh winds (e.g., St. John's wort, wormwood).

Herbaceous plants are those whose underground Organs with renewal buds survive, while the above-ground shoots exist for a single growing season and then die off. Examples include couch grass, fescue, strawberries, white dead-nettle, lungwort, and white clover.

Annual herbaceous plants complete their full developmental cycle (from seed to seed) within a single year. These include most field crops (peas, beans, corn, oats, barley, dill).

Biennial plants complete their developmental cycle over two years: in the first year, they form a rosette of basal leaves and accumulate nutrient reserves in their roots, while in the following year, they produce inflorescences that develop into fruits. After fruit set, the plants die (carrot, radish, beet, mullein, chicory).

Perennial herbaceous plants possess long-lived underground parts that produce new above-ground shoots every year. These shoots die back at the end of the growing season. Examples include feather grass, sedges, rushes, and fescues (Fig. 64).

Stems vary extraordinarily in their longevity. Some plants exist for only a single growing season, while others live for over 5,000 years (baobab), yew for 3,000 years, chestnut for 2,000, oak for 1,200, linden for 1,000, beech for 600-900, pine for 500, walnut for 300, apple for 200, and grapevine for 100 years.

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Fig. 64. Life forms based on biological stem types:

1 - tree, 2 - shrub, 3 - dwarf shrub, 4 - grass-like herb, 5 - subshrub

Stem sizes range from 1.0-1.5 mm (watermeal) to 155 m (Australian eucalyptus). The coast redwood reaches a record height of 142 m, spruce - 75 m, pine - 50 m, poplar - 40 m, birch - 30 m, corn and reed - 3-4 m, orchard grass - 0.6-1.5 m, fescue - 60-80 cm, ground ivy and violet - 10-20 cm.

Naturally, plants vary in stem thickness. Herbaceous plants have a thickness of 4-8 mm, shrubs - 2-8 cm (hazel), trees - 0.5-3 m (apple, beech), and the swamp cypress can reach 12-14 m.