Part 102. The vegetative organs compared. Let us begin by comparing the marsh-marigold as a type of the family with the other representatives here illustrated. This plant we know to be an herb because the parts above ground are too tender and succulent to live through the winter. The roots do persist however, and serve as storehouses for food which the plant uses in the following spring.

Thus it is enabled to live from year to year, or, in a word, is a perennial. Whenever we find an herb retaining the remains of more or less withered leaves and stems, or of shrunken roots evidently belonging to a previous year, and at the same time having organs, underground or near the surface, swollen with food evidently destined to supply material for the growth of buds fitted to live over the winter we may safely conclude that we have a perennial plant. If, on the contrary, a full grown herb lacks all such signs of a previous year's growth or of provision for the future, it is clearly an annual; while if there are signs (such as a swollen root or leaf-rosette) implying only a past year's growth with no provision beyond, the plant would be called a biennial, i. e., one completing its life in two years.

Nearly all the members of this family are perennial herbs. A few, such as the mouse-tail, are annuals; and there are some more or less woody forms, as for example, certain species of Clematis which are woody and climbing. None of the family are trees.

The stem parts of the marsh-marigold agree fundamentally with those of the flax plant in their general form and mode of branching, although differing in such minor details as slenderness and toughness. There is, however, a more significant difference in the length of the lower internodes, which in the marsh-marigold and many other members of the family are so short that the foliage leaves are crowded together into a rosette. Somewhat similarly abbreviated internodes bearing scale-like leaf-members often remain underground, as in the wood-anemony and the Christmas rose, and persist over the winter as a reservoir of food upon which buds may feed the following spring. Such an elongated subterranean stem is called a rootstock or rhizome.1 When, as in the bulbous crowfoot, the subterranean base of the stem becomes so much gorged with food as to be sphaeroidal or oblate in form it is termed a "solid bulb" or corm.2

Turning now to the foliage of our marsh-marigold we find the leaves to be of a form very common among seed-plants, and comparatively simple although more highly developed than the leaves of flax. In a marsh-marigold leaf we may distinguish a broadly expanded part, the blade, borne on a footstalk or petiole;3 which expands again at its base into a sort of sheath. The framework of the leaf when it reaches the blade divides into a number of main branches, or ribs. These radiate from the top of the petiole and may divide again into secondary branches, or veins, which finally are connected so as to form an irregular net-work by minute branches called veinlets. When a leaf has ribs radiating thus, like the bones in the palm of one's hand, it is said to be palmately ribbed, and when the veinlets form an irregular net-work, it is netted-veined. The ribs and veins are also called nerves and their arrangement the nervation of a leaf, the arrangement of the veinlets being called the venation.

1 Rhiz-ome - Gr. rhiza, root, because of its root-like appearance.

2 Corm - Gr. kormos, a pollarded tree-trunk.

3 Pet'-i-ole - L. petiolus, a little foot, diminutive of pes, pedis, a foot.

On comparing with the leaves of the marsh-marigold those of the ditch crowfoot we find the same general plan of structure but with the difference that the leaf base is narrower, and the blade is divided into branches corresponding to the ribs. The branches of the upper leaves are so narrow as to suggest a resemblance to the toes of a bird, which has given rise to the name "crowfoot." In the tall crowfoot the branching of the blade is carried still further and follows the veins. A similar branching is shown in the leaves of monkshood and many other members of the family.

All the leaves so far considered agree in having the blade of a single piece however much it may be branched or subdivided. That is to say, the green pulp of the blade, although it may be but little developed between the ribs, is still continuous. Such are called simple leaves. When the green pulp is discontinuous between the ribs, as in the leaves of the Christmas rose, the blade becomes divided into secondary blades or leaflets, each of which may be borne on a little stalk of its own, called a petiolule.4 Such leaves are classed as divided or compound. If, as in this example, the leaflets or their petiolules spring directly from the main petiole the leaf is distinguished as once-compound; when, as in baneberries, the branching of the blade is carried a stage farther and the leaflets or their petiolules arise from branches of the petiole, the leaf becomes twice-compound; or the subdivision may be carried still farther, as in columbines. A leaf more than once compounded is termed decompound. Since in all these cases the branching of the blade follows the palmate plan the leaves are conveniently described as palmately divided, or palmately once-, twice-, or decompound. The leaves of the Christmas rose and some other members of the family are peculiar in having the lateral divisions not quite separated, thus making them in a way intermediate between simple and compound palmate leaves. Such leaves are distinguished as pedate.5

4 Pet'-i-o-lule - L. petiolulus, diminutive of petiolus, petiole.

5 Ped' ate. - L. pedatus, having a foot.

The palmate type of leaf prevails throughout the crowfoot family, the only departures from the rule being a few such cases as the narrow leaves of mouse-tail in which the framework is unbranched or obscure, and a few cases in which a midrib or continuation of the petiole gives off lateral branches as in the leaves of the pasque-flower and clematis (Fig. 291). The relation of the very narrow mouse-tail leaf to one of the marsh-marigold type may be understood by supposing the nerves to be reduced to a single rib. A leaf in which the framework consists of only one or two ribs, may be termed costate.6 The simple leaf of the silky clematis may be likened to a less narrowed marsh-marigold leaf in which, however, the ribs are reduced to one midrib from which veins are given off on either side. Or, better, we may view it as an elongated leaf in which the framework was at first divided palmately into three branches, the middle one of which again divided similarly, and this method of branching continued during the elongation of the blade. However we may view the nervation, such a leaf in which a single midrib, or direct continuation of the petiole, gives off several or many lateral branches, is distinguished as pinnately nerved. The leaves of the pasque-flower are described as pinnately compound or pinnate.7 The leaflets of the Christmas rose are pinnately nerved, the leaf as a whole being palmate or pedate.

6 Cos'-tate - L. costa, a rib.

7 Pin'-nate - L. pinna, a feather, because the veins arise from the midrib as do the barbs of a feather from its shaft.