But the lily's many kin have each, as the ponderous term monocotyledon implies, but a single seed-leaf. In the ripe grain- or grass-seed it has a peculiar shield-like form, and it is wrapped completely around the second leaf and the stem that is to be. When the grain begins to sprout the upper end of the cotyledon remains in the seed and feeds on the nutriment which has been stored there. But its lower part lengthens and pushes all the rest of the little plant out into the world.

This cotyledon's main purpose in life is to absorb the starches and other nourishing things packed away in the grain, and not to digest crude sap, as most leaves do. It has, in most instances, no use for chlorophyll, and therefore it is seldom green.

We may find it near the roots of a young grass-plant, shrivelled away, now that its work is done, to a little horny, brownish scale.

The second leaf of the young monocotyledon is developed later than the seed-leaf, and higher up on the stem, and the third comes later and higher still. So when the growing lily or wheat is a few inches above ground we see that its leaves are scattered along the stem, each singly and alone.

Parallel veined leaves of the Indian shot (Carina Indica).

Fig. 24. - Parallel-veined leaves of the Indian shot (Carina Indica).

(From the Vegetable World).

When the plant is a little older this alternate arrangement may be abandoned for some more complex plan. The leaves of some lilies are borne in circles, like spokes of a wheel, and those of some of the lilies' cousins are so ranged along the stem that a line drawn through the point of insertion of each will go winding upward in a beautifully symmetrical spiral.

One of the most marked characteristics of Mono-colyletons is the veining of the leaves.

By this alone we can generally tell almost at a glance whether a plant is to be classed with the lily or with the rose.

The foliage of the lily-kin generally has what botanists call parallel veins (Fig. 24).

A mathematician would take exception to the term, for parallel lines, as we all know, never meet, while parallel leaf-veins come together at the leaf's tip.

But the student of plant-life who called the veins of lily-leaves and grass-blades "parallel," was probably comparing them to the veins of di-cotyledenous foliage, which twist and branch into a mesh-work as bewildering as it is beautiful (Fig. 25).

The leaves of lilies and their kin are almost always simple in outline, - arrow-shaped, heart-shaped, oval, or long and narrow, like blades of grass.

Branched leaves occur only rarely and exceptionally among the palms, and in a few of jack-in-the-pulpit's eccentric cousins. But the bladelike foliage (Fig 26) is borne by many plants among the lily's kin - the crocus, iris and spiderwort, the orange-colored lily of old-fashioned gardens, the blue-eyed grass, the cat tail flags, and other familiar flower friends. Such leaves, like grass-blades, have no true stalks, but spring from sheaths which enfold the stem. These clasping bases and perfectly straight veins are characteristic of the narrow foliage of monocotyledenous plants. Whether narrow or broad, the leaves borne by the lily's kin have, as a rule, straight edges, plain and unadorned.

Net veined leaves of the lime tree. (From the Vegetable World).

Fig. 25. - Net-veined leaves of the lime-tree. (From the Vegetable World).

Blade like leaves of the iris, with clasping bases.

Fig. 26. - Blade-like leaves of the iris, with clasping bases.

(From the Vegetable World).

The leaves of the rose's kin are far more elaborate in effect. Sometimes, as in the case of the rose itself, each of them is "compound" - made up of a number of smaller leaves. Sometimes they are cut into delicate lace-work, as is the foliage of the yarrow and of the domestic carrot.

Sometimes, like the leaves of the rose-geranium, they are curiously slashed, and in many cases their edges are daintily cut into points, teeth, or scallops.

Their veins, as we have already observed, run "every-which way," and even when the larger veins parallel one another with copy-book precision, as in the chestnut-leaves, the veinlets wander here and there in graceful lawlessness.

It is in the tissue of the stem, and in its mode of growth, that the chief distinction between the two greatest groups of flowering-plants is to be found.

Next to the palmettos, which are not found in a wild state north of the Carolinas, the Indian corn is the largest of native monocotyledonous plants. If we cut a thin, cross-wise slice out of a corn-stalk we need no microscope to show us its internal structure. We see that there is no separable bark, and that the woody substance is in delicate threads, which are scattered all through the pithy interior, but are most numerous toward the outside of the stalk. The palmetto trunk is built after the same plan, but its woody threads are so tough, and so closely massed together, that they make a material hard enough to be useful to the cabinet-maker (Fig. 27).

Crosswise section of a palmetto trunk.

Fig. 27. - Crosswise section of a palmetto trunk.

(From the Vegetable World).

If we could detach a single woody thread from the corn-stalk, cut a thin, crosswise slice of it, and examine it with a powerful microscope, we should see that it is a compact bundle of small filaments, and that each filament is a row of short tubes or vessels. Transverse partition-walls separate one vessel from another, and these walls are sometimes horizontal and sometimes aslant. An inquiry into the names and uses of all these vessels would take one far into the mazes of structural botany.