tutored 10 negro to worship under its shade, and hail the opening of its flowers with pious veneration.11 9. But even the great baobab must yield in dimensions to the mammoth red-wood trees of California. One of these trees was three hundred feet in height, and thirty in diameter, and its bark was fifteen inches in thickness. When it was felled,12 the trunk was perfectly sound to the centre. The largest of the group, known as the "Father of the Forest," has long been prostrated; but it is great even in its ruins. It is estimated that it was four hundred and twenty feet in height, or only a few feet lower than the highest of the Egyptian pyramids. 10. The stems of some trees send down branches which take root in the earth and form new trunks. The most remarkable instance of a plurality of trunks is seen in the banyan-tree of India. It has at first but one stem; but from the branches leafless shoots are sent down, which, taking root, become secondary stems. This process is repeated till one tree makes a forest. There is said to be one in Hindostan with three hundred and fifty larger trunks and three thousand smaller ones, covering seven acres, and furnishing shelter for seven thousand men. 11. These magnificent natural temples are esteemed 13 sacred by the Hindoos, and are dedicated11 to religious rites.15 Milton has beautifully described this tree: "Branching so broad and long, that in the ground About the mother tree, a pillar'd shade, High over-arched, and echoing walks between." 12. Another kind of stem, remarkable in many respects, is that of the cactus, an order of plants found almost exclusively in America, and abundant in Mexico, Oregon, and California. They are usually leafless plants, presenting their juicy stems under a great variety of forms, from that of an egg to a lofty fluted column, and, in the case of the giant cactus of California, exhibiting a leafless branching trunk fifty or sixty feet in height. Growing mostly in hot, dry, and rocky places, where they are exposed for many months in the year to the fiercest beams of a tropical sun, they are remarkably adapted, by a wise provision of Nature, to the situations in which they are destined to live. 13. During the wet season of the year they grow rapidly, and so fill themselves with nourishment that they may be literally said to gorge16 themselves with food. Then, when the rains cease, and the air becomes dry, and the spirit of the desert resumes his withering dominion over their climate, Fig. 10, Cactus Plants. At 1 is seen the Cactus opuntia, or prickly-pear cactus, its stem and branches forming a succession of thick and flattened joints; at 5 is one similar, but with shorter and flatter joints; 2 and 4 are plants belonging to the Cereus genus of cactuses, the latter being the giant cactus of California, which rises to the height of 50 or 60 feet; 3 is the melon cactus; and 6 is the Cereus speciosissimus in full bloom. and all the gay companions of the cactus droop and die, these juicy plants, closing their pores to prevent evaporation,17 feed on their garnered18 stores, and preserve the most robust health, not for days merely, but for months. In their power of enduring long-continued drouth,19 they may be considered to fill that place in the vegetable world which is occupied in the animal kingdom by the camel of the desert. 1 CON-SPIC'-U-OUS, plain; easily seen. 6 FUN'-GUS (fung'-gus), like a mushroom. 110 UN-TU'-TORED, not instructed; untaught. 13 ES-TEEM'ED, regarded; held. higher 16 GORGE, to fill to overflowing; to glut. 8 RE-NOWN', repute; notoriety; so well known. 9 IN-SPEC'-TION, view; examination. 18 GÄR'-NERED, gathered; laid up in store. 19 DROUTH, dryness; want of rain. 1. 'Twas a fair scene wherein they stood, That venerable tree; For o'er the lawn,2 irregularly spread, 2. And many a long depending shoot Straight, like a plummet, grew toward the ground. 5 With many a ring and wild contortion wound; Others of younger growth, unmoved, were hung, Nor weeds nor briers deform'd the natural floor; So like a temple did it seem, that there A pious heart's first impulse would be prayer. 1 GLADE, an opening in a wood. 2 LAWN, a space of ground covered grass. 3 €ŎL'-UMNS (kõl'-ums), stems. 4 DE-PEND'-ING, hanging from. SOUTHEY. 15 FI'-BRES, thread-like roots or tendrils. with 6 CON-TOR'-TION, a twisting. 7 FRET'-TED, interwoven like net-work. LESSON VIII. THE LEAVES OF PLANTS. 1. Ir has been seen, in the article on Human Physiology, that in the cuticle or skin of man there are little openings or pores, which may be regarded as the breathing-holes of the skin, but that the lungs are, nevertheless, the principal organ by which the blood is purified. Leaves may be considered the lungs of plants; for in the cuticle or covering of all green leaves there are minute apertures,1 like the openings of the perspiration tubes in the human skin; and it is through these that the sap is brought in contact with the air for purposes of respiration2 and exhalation.3 2. So minute are these openings, visible only by the aid of the microscope, that more than one hundred thousand of them occurs in a square inch of the surface of some leaves. They are usually most numerous on the under side of a leaf, except where both sides are equally exposed to the influence of air and light. The number of these breathing mouths in a single tree of some kinds is almost beyond calculation; for it has been estimated that the leaves of a single large elm-tree have a leaf surface of not less than five acres! (Fig. 11.) 3. We have seen that the first and most important division of leaves is into net-veined and parallel-veined, the former belonging to exogenous plants, and springing from two-lobed seeds, as the acorn and the bean; and the latter belonging to endogenous plants, and springing from single seeds, as the palms and the grasses.* Leaves are also classified as simple and compound. Their principal varieties may be learned from the accompanying illustrations. 4. The surface of the leaf also affords a means of classification into smooth, downy, hairy, and rough leaves. According to their duration, leaves are called fugacious" when they fall off during the summer, deciduouss when they fall in autumn, and persistent when they remain during the winter, and gradually give place to new leaves in the spring. 5. In cold regions leaves are small and highly polished, as if to reflect what little heat and light may fall upon them. Plants growing on mountains and dry places have gutters to *The seeds which have two lobes are called by botanists di-co-tyl-e'-don-ous, because, when they germinate, they produce two co-tyl-e'-dons, or seed-leaves. The single seeds are called mon-o-co-tyl-o'-don-ous, because they produce but a single co-tyl-e'-don, or seed-leaf. Fig. 11. Fig. 11 is a horizontal section of a leaf highly magnified. At v, v, v are shown the small veins in the leaf, and s, s, s indicate the little pores or breathing-holes, which, in botanical language, are called stomata or stomates. Destroy the leaves of a tree in midsummer, and, as the tree will then be unable to breathe, it will wither, and in most cases will soon die. I |