Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
woody plant:see herbaceous plantherbaceous plant
, plant whose stem is soft and green and shows little growth of wood. The term is used to distinguish such plants from woody plants. Herbaceous plants, or herbs, as they are commonly called, may be annual—that is, the plants die after a year's growth, and
..... Click the link for more information. .
a plant species, such as birch, spruce, oak, or pine, that produces wood. Woody plants are represented by various life forms— trees, shrubs, and undershrubs. The height of trees, which is dependent on species characteristics and growing conditions, ranges from several dozen centimeters (dwarf willows) to 100 m or more (sequoia, eucalyptus).
Trees of the first magnitude are more than 25 m tall (spruce, larch, oak), trees of the second magnitude reach 15–25 m in height (common maple), and trees of the third magnitude are under 15 m tall (apple). In forests, trees of the first magnitutde form the canopy, or first stratum. Second-magnitude trees usually make up the second stratum, occasionally wedging themselves into the canopy of the first stratum. Trees of the third magnitude occupy the third stratum and, sometimes, form part of the undergrowth (shrub forms). Shrubs range in height from 0.8 to 6 m, and undershrubs from 5 to 60 cm. The trunk diameter of woody species varies significantly, from less than 1 cm (cowberry) to several meters (baobab).
The majority of woody plants with well-developed leaf blades are called hardwoods (oak, linden); those having narrow needlelike or scalelike leaves (needles) are called conifers (spruce, pine, thuja). In some hardwoods, such as saxaul, the leaves are reduced to nodules. Depending on the size of the leaf blade, hardwoods are divided into small-leaved species (birch, aspen) and broad-leaved species (oak, linden, maple); the forests formed by them are called small-leaved and broad-leaved, respectively. Woody species that retain their leaves (needles) for several years are called evergreens. Such plants include the majority of conifers and many hardwoods found in the tropics and subtropics, such as the eucalyptus, the magnolia, the laurel, palms, and the fig. Deciduous species shed their leaves for the winter. Most hardwood trees of temperate climates (birch, elm, maple) are deciduous, as are such conifers as the larch.
All woody plants are perennial, with life-spans ranging from several dozen years (speckled alder, some species of willow) to 3,000-5,000 years (sequoia, baobab). In terms of their light requirements, woody species may be classified as shade tolerant (fir, yew, hornbeam) or photophilic (larch, birch). Shade-tolerant conifers (spruce, fir, Siberian stone pine) form dark coniferous forests, and photophilic conifers (Scotch pine, larch) form light coniferous forests. Winter-hardy woody species tolerate frosts to –60°C; they also withstand freezing and winter desiccation (larch, pine, birch). Cold-resistant species tolerate frosts to -30°C (oak, linden). Thermophile species grow under conditions of mild winters with temperatures above 20°C (sycamore, sweet cherry); extremely thermophile species die at sub-zero temperatures (palm).
Species that readily tolerate dryness of air and soil are called xerophytes (saxaul, saltwort, pine), and those that require large amounts of moisture are called hygrophytes (black alder, many species of willow). Some species grow only on fertile soils (oak, fir, linden); others do not require any particular soil conditions. Woody species that need soils with a high calcium salt content are called calcicoles (Larix Sukaczewii); species that cannot tolerate lime in the soil are called calcifuges (chestnut). The gas resistance of woody species varies: most gas-resistant species are deciduous; those that are less gas resistant are evergreen. Woody species with well-developed root systems are wind resistant (oak, larch); however, those with superficial root systems are susceptible to windfall (spruce). Woody species vary with respect to resistance to disease and insect pests.
Woody species are classified according to economic value and the space they occupy as principal (oak, pine, spruce) or secondary (linden, maple) species. Some species, including oak and larch, have wood with well-developed heartwood and sapwood. The wood is distinguished for its strength and durability. Some species have lightweight wood, which lacks heartwood and is less durable (spruce, fir). The coloring of the wood varies: aspen and spruce are almost white, pine has reddish heartwood and yellowish sapwood, pear is pinkish, sequoia and yew are red, and plane has brown heartwood with silvery medullary rays. The wood of some species is highly ornamental. Walnut (especially its burls), Karelian birch, and sycamore have very beautiful grains and are valuable finishing materials. The wood is used for making art objects. In using woody species in landscaping, consideration is given to their ornamental properties (shape of the crown, seasonal coloring of the leaves, flowers, and fruits), size, life form, ability to tolerate pruning, and gas resistance.
REFERENCESSee references under FOREST.
T. A. MELEKHOVA and A. IA. LIUBAVSKAIA