79. Q. What is the stem of a plant? A. That part which bears the leaves, flowers, and fruit.
80. Q. What is the length of life of the stem and roots? A. It may be only a single year, or annual; two years, or biennial; or a number of years, or perennial.
81. Q. What are thorns? A. Undeveloped branches, and many plants which are thorny when wild are not so under cultivation.
82. Q. Of what are leaves constituted? A. Cells, with cavities, fibro-vascular bundles and epidermis.
83. Q. How do the veins in the leaves of Endogens differ from those in the leaves of Exogens? A. They are generally parallel or straight in Endogens, and do not form a network as in Exogens.
84. Q. What are five of the names given to leaves according to their shapes? A. Lanceolate, or narrow and tapering; oblong, or narrow and not tapering; cordate, or heart-shaped; sagittate, or arrow-shaped; and ovate, or egg-shaped.
85. Q. What is the function or use of leaves? A. To expose the juices of the plant to light and air, and thus aid in forming the woody matter of the stem and the various secretions.
86. Q. What constitute a plant’s organs of nutrition? A. The root, stem and leaves.
87. Q. What is the flower of a plant? A. It is the organ, or assemblage of organs, for the production of the seed.
88. Q. What are the four whorls in which the parts of a flower are usually arranged called? A. The outer whorl is the calyx, the next the corolla, the third the stamens, and the innermost the pistil.