« AnkstesnisTęsti »
and all the gay companions of the cactus droop and die, these juicy plants, closing their pores to prevent evaporation,17 feed on their garnered 18 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.
2 CON-CEN-TRIE, having a common centre.
6 FUN'-GUS (fung'-gus), like a mushroom.
RE-NOWN', repute; notoriety; so well
9 IN-SPEC-TION, view; examination.
1. 'Twas a fair scene wherein they stood,
It was a goodly sight to see
For o'er the lawn,2 irregularly spread,
Fifty straight columns3 propped its lofty head,
And many a long depending shoot
Straight, like a plummet, grew toward the ground.
Others of younger growth, unmoved, were hung,
1 GLADE, an opening in a wood.
2 LAWN, a space of ground covered grass.
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.
3 €ŎL'-UMNS (kõl'-ums), stems.
4 DE-PEND'-ING, hanging from.
15 FT'-BRES, thread-like roots or tendrils with 6 CON-TOR'-TION, a twisting.
7 FRET'-TED, interwoven like net-work
THE LEAVES OF PLANTS.
1. It 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 respiration 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 occur 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 classifications into smooth, downy, hairy, and rough leaves. According to their duration, leaves are called fugacious' when they fall off during the summer, deciduous 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-o'-dons, or seed-leaves. The single seeds are called mon-o-co-tyl-e'-don-ous, because they produce but a single co-tyl-o'-don, or seed-leaf.
Fig. 11 is a horizontal section of a leaf highly magnified. At v, v, v are shown the small veins in the leaf, and 8, 8, 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.
convey the moisture that may fall upon them to their roots. In tropical countries leaves grow large and broad, as the tallipot palm of Ceylon, whose single leaf often affords covering for a whole family.
6. Sometimes leaves present very singu lar forms, as those of several species of pitcher-plants, some of which have connected with them complete vases, with a nicely fitting lid or cover. Many of these plants are found in Southern Asia. The cup of the Chinese pitcher-plant holds about a tumblerful of sap, which is poured out from its inner side. This plant is quite common in Ceylon, where it is called monkey-cup, because the monkeys sometimes open the lid and drink the water. (Fig. 12.)
7. In India there is also a climbing stem of a species of the pitcher-plant, one hundred feet long, and destitute of leaves till near the extremity, so that it seems impossible that it should receive its nourishment from the ground by absorption.10 This
Fig. 12.-At 1 is a species of Dischidia, in which the pitcher is at the end of the stem, which grows through the leaf. At 2 is the Nepenthes distillatoria, the true pitcher-plant of India. The pitcher is at the end of an extension of the midrib of the leaf. At 3 is the Sarracenia purpurea, the American side-saddle flower, in which a leaf, collapsing and uniting at its edges, forms the pitcher. At 4 is also a species of the Nepenthes, often called the Chinese pitcher-plant. The lid is generally shut down.
I. SIMPLE LEAVES.-At 1 is what is called a linear leaf. It is also parallel-veined, like Nos. 21, 23, and 24, showing that it belongs to the plants which have but one co-tyl-e'don, or seed-leaf. At 2 is a lan'-ce-o-late leaf; 3, el-lip'-tic-al leaf: 4, o'-vate; 5, oblan'-ce-o-late; 6, ob-o'-vate; 7, cu'-ne-ate, or wedge-shaped; 8, sag-it-tate; 9, au-ric'u-late, or eared, and sag'-it-tate when the ears are pointed and turned downward; 10, has'-tate, or spear-shaped.
At 11 is a leaf that is both o'-vate and a-cate'; 12 is cord'-ate, or heart-shaped; 13, ren'-i-form, or kidney-shaped; 14, pelt'-ate, or shield-shaped, and also or-bic'-u-lar; 15, lobed, or pinnately-lobed; 16, pinnately-cleft; 17, pinnately-parted; 18, pinnately-divided.
plant has a pitcher or cup, but without any lid, formed of a leaf with its edges rolled toward each other till they meet and adhere,11 while the upper part, from which it is suspended, is open to receive the rain or dew.
8. This pitcher always contains a fluid, composed of the sap of the plant and water, in which a number of black ants and flies are generally seen. It is supposed that by their decomposition 12 the plant is nourished. A still more wonderful appearance is presented by a tuft of fibres,
hanging from the branch, and dipping into the pitcher, apparently for a new supply of aliment.13 (Fig. 13.)
9. A very singular plant grows in North and South Carolina, on the Cape Fear and Santee rivers, which is especially adapted to catching flies, and hence is called a fly-trap. The trap is open when the sun shines, ready, as soon as a fly touches any of the long hairs within its leaves, to close suddenly, and hold it fast until its struggles are over, when it slowly opens for another victim. The locality of this vegetable wonder, a drawing of which is here given, is confined to the region of the rivers named above, nor is it
found in any other part of the world. (Fig. 14.)
Fig. 13 is the Dischidia rafflesiana of Asia, in which the pitcher is a leaf united at its edges. This pitcher has no lid.
Fig. 14 is the Venus fly-trap, Dionaea muscipula, of Carolina. At a and b are flies, caught by the sudden closing of this singular leaf-trap.
II. COMPOUND LEAVES.-At 19 are pinnate leaves, or those in which the leaflets are arranged on the sides of a main leaf-stalk. Pal'-mate or dig'-it-ate leaves are those in