. Science of plant life, a high school botany treating of the plant and its relation to the environment. Botany. Herbs, Shrubs, and Trees 97 fact that m annuals, biennials, and a few perennials there is no well-marked period of senility or old age. They die sud- denly at maturity, immediately after their period of greatest vigor. Trees and shrubs, on the contrary, have a distinct period of old age in which the physiological pVocesses are slowed down gradually until the plants suc- cumb to diseases and unfavorable conditions which they could have withstood in youth. Perennials classified accord
. Science of plant life, a high school botany treating of the plant and its relation to the environment. Botany. Herbs, Shrubs, and Trees 97 fact that m annuals, biennials, and a few perennials there is no well-marked period of senility or old age. They die sud- denly at maturity, immediately after their period of greatest vigor. Trees and shrubs, on the contrary, have a distinct period of old age in which the physiological pVocesses are slowed down gradually until the plants suc- cumb to diseases and unfavorable conditions which they could have withstood in youth. Perennials classified according to the persistent parts. All perennials add new leaves, new stems, and new roots each year; but they may be classified roughly according to the parts that persist from one season to the next. Evergreen trees and shrubs are perennial in all parts of the plant body. Deciduous trees and shrubs are perennial in their stems and roots. Many herbaceous perennials, like the cat-tails, swamp mallows, peonies, triUiums, and bananas, have annual above-ground stems but perennial underground stems and roots. DahHas and sweet potatoes have perennial roots. Potatoes and the Jerusalem artichoke (a kind of sunflower) have perennial thickened underground stems (tubers). Tulips and hyacinths have perennial underground stems (bulbs). These examples show that perennial plants have many different ways of bridging. Fig. s8. Century plant {y4ja»c), showing rosette of fleshy leaves and flowering stem. It is a perennial, but, like an annual or a biennial, it dies when it flowers and Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Transeau, Edgar Nelson, 1875-1960. Yonkers-on-Hudson, N. Y. , World Book Co.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbotany, bookyear1921
