sharp and rigid point; aristate, when the end is tipped with a bristle point; entire, when the leaf is entirely filled out; serrate, when the margin is cut with sharp teeth; dentate, when the teeth point outward; crenate, leaf with rounded teeth; repand, when the margin of the leaf forms a wavy line; incised, when the margin is cut into sharp, deep, and irregular teeth; lobed, when the leaf is deeply cut. It is generally said to be aconite. lobed where the divisions do not extend more than half way between the margin and the midrib, the divisións being more or less rounded; cleft, where the divisions extend more than half Fig. 48. Lobed leaf of (Ada Hayden.) Fig. 49. Leaves of various types: 1, undulate; 2, thistle leaf with acute lobes; 3, lobed leaf of oak; 4, lyrate; 5, pinnately divided leaf; 6, pinnatisect. way and are sharp; parted, where the divisions extend deeper, but do not reach the middle; divided, where the divisions extend nearly to the midrib. A leaf may be pinnately lobed or palmately lobed; palmately cleft or pinnately cleft, etc. Some leaves, like those of pea and many other plants of the same order, are provided with a slender filiform body called a Fig. 50. Radiate veined leaves: 4, 5, cordate; 6, 7, kidney; 8, peltate. Fig. 55. 3, elliptical; 4, oblong leaf; 5, obovate; 6, cuneate or wedge shaped. Fig. 54. Apex of leaves: 1, 3, types of obcordate leaves; 2, emarginate; 4, . truncate. mm 5 6 7 8 9 Fig. 56. Apex of leaves: 5, obtuse leaf; 6, acute; 7, acuminate; 8, 9, mucronate. Fig. 57. 7, shield-shaped leaf; 8, acutely three-lobed leaf; 9, peltate palmately lobed leaf of castor oil; 10, 11, types of palmately compound leaves. tendril. These tendrils are modified leaves, while those of the grape are modified stems. Flowers. Flowers are for the purpose of producing seed and are merely altered branches; the parts of flowers are therefore altered leaves. The manner in which Fig. 58. Inflorescence. Catkin of birch: 2, staminate flowers; 3, pistillate flowers. flowers are borne upon the stem is important in enabling one to distinguish different plants. The manner in which the flowers are borne is called the inflorescence, and there are two types: the determinate, where the terminal bud opens first; and the indeterminate, where the flowers develop from below. The more important types of indeterminate inflorescence are the following: Raceme, a simple flower cluster in which the flowers are attached to a little stalk called a pedicel, and are arranged along a common axis. Examples are: The cur- purse, and lily of the valley. A corymb is much like a raceme, except that the flowers are more or less level at the top and the pedicels are of different lengths. In an umbel the flower cluster is much the same as in a corymb, but the stalks are all of the same length; in other words, the flowers come from the end of the stalk. Fig. 59. Inflorescence. Cymose cluster of pink. The milkweed and carrot have umbels. The spike is like a raceme with a lengthened axis, the flowers being sessile, like those of the plantain. A head is a roundish cluster of flowers which are sessile, as in the clover and buttonball. The spadix is a fleshy spike, as in the Indian turnip, the spathe being the leaf over the spadix; the flowers of the spadix are imperfect. The catkin is a type of inflorescence found in the willow and hickory. The panicle is a compound flower cluster found in many grasses; that is to say, it is like a raceme, but the Fig. 60. Inflorstalks are branched escence. Spike of again. Of the deter- cat-tail. (Dudgeon.) minate inflorescence the most important is the cyme. The cyme is a flat topped or convex flower cluster somewhat like the corymb, but with the terminal flower developing first. A glomerule is a cyme very much compacted, resembling a head. Fig. 61. resce..ce. Head of ragweed, achene above. (C.M.King.) Flowers are perfect or hermaphrodite when provided with the essential organs, stamens and pistils; complete when they have all the floral envelopes, calyx, corolla, and stamens and pistils; regular when all the parts of each set are of the same shape and size, like the rose; irregular when some of the different floral circles are dissimilar or unequal, as in the clover, wood sage, and mint; monoecious when both staminate and pistillate flowers are produced by the same individual plant, as in corn; dioecious when the two kinds are borne on different plants, as in willows, poplars, hemp, and moonseed. Polygamous when some of the flowers are perfect Fig. 65. Inflorescence. Fig. 64. Inflorescence. Head of clover. (C. M. King.) and some have pistils or stamens only. Flowers in which the petals are separate are called polypetalous; when the Head of wild lettuce. petals are united, gamopetalous; when The type of inflores- the petals are wanting, apetalous. cence in the sunflower family. (C. M. King.) In some flowers different parts or |