52 



ANALYTICAL CLASS-BOOK OF BOTANY. 



leaves of such a plant are represented as being folded 

 together, while a third is open. The folding depends on 

 a constitutional irritability, which will be discussed in 

 its proper place. In the Water-Chestnut, fig. 10, the 

 petiole is dilated into an air-tube, which may serve as a 

 buoy to the floating leaves. This beautiful economy is 

 often observed in Seaweeds, and other aquatic plants. 



290. But there is nothing of the kind more curious 

 and remarkable, than we find in the twining plant of the 

 East Indies, called Dischidia. This plant ascends to 

 the summit of the tallest trees, sometimes putting forth 

 leaves a hundred feet from its base; while the whole 

 stem below, being without leaves, can elaborate no food. 

 The pitcher, which resembles a Hang-bird's nest, appears 

 to be formed of a leaf, whose edges roll together a,nd 

 adhere, closing entirely at the bottom ; while at the top 

 it remains open, to admit all the moisture that falls in 

 its way ; and usually it contains a considerable quantity. 

 But the most wonderful part of its economy is yet to be 

 told. From the nearest portion of the stem several root- 

 like processes are sent out, whose fibrils, entering these 

 little cups, absorb the moisture, which the upper parts of 

 the plant, in their insular situation, their great distance 

 from the root, and the want of leaves below, could not 

 otherwise attain. So wonderful and admirable are the 

 means which often, in the absence, or irregular position 

 of any organ, supply its place, and fulfil its ofiices. 



STIPULES. 



291. These are leafy appendages situated at the base 

 of the leaf, or leaf-stalk. They usually occur in pairs, as 

 in the Cherry, fig. 1, and the Lentil, fig. 3, Plate XVIII. 

 In the Pansy, fig. 2, they are large and conspicuous, 

 appearing to form a portion of the proper foliage. They 

 often seem designed for the protection of the young 

 leaves, for when the leaves develope the stipules dis- 

 appear. 



292. There is one fact in vegetation worth observing 

 and remembering, which is, that tender and growing 

 parts coming in contact are very apt to cohere, and thus 

 form irregular, and in some respects accidental, combi- 

 nations. This is particularly true of stipules ; for their 

 various modifications appear to be chiefly owing to their 

 different modes or degrees of coherence with each other 

 and the adjoining parts. They are 



(1) ADNATE, when they cohere with the base of the 

 foot-stalk, as in the Strawberry and the Rose, fig. 6; 



DiscliMia, describe. Of what do its rootlets supply the want? What are 

 Stipules? How usually occur?. What fact worth remembering? Of what 

 particularly true ? Varieties of the Stipule. What processes may be con- 

 sidered stipular? How are tho Stipules in the Plane? Agrimony. "When 



(2) INTRAFOLIACEOUS, in alternate-leaved plants 

 when both margins cohere, so as to form a sheath round 

 the stem, as in the Rhubarb. When stipules of this 

 form are short, dry and membranaceous, they are termed 

 ochrea, as in the Buckwheat tribe, one of which is repre 

 sented at fig. 7 ; 



(3) INTERPETIOLAR, when they occupy the spaces on 

 each side of opposite leaves, as in fig. 1 1 ; 



(4) SPINESCENT, forming thorn-like processes, as in 

 the Rose-Acacia, fig. 5 ; and they are called 



(5) LIGULES, in the Grasses, where they form certain 

 membranaceous, sheathing appendages peculiar to the 

 Order, as in the pointed process from the base of the 

 leaf at fig. 10. 



293. The sheathing outgrowth from the base of the 

 petiole, in the Fennel tribe, may properly be considered 

 stipular, as in the Dill, fig. 4. The Low Cornel, fig. 8, 

 has a pair of small stipules, about mid-way, investing its 

 stalk. In the great Plane-tree, the cohering stipules 

 form one foliate body, situated opposite to the leaves, 

 which are alternate ; and in the Agrimony, fig. 9, they 

 unite in the same manner, and surround the stem. 



294. When leaves are furnished with stipules, they 

 are said to be STIPULATE ; when they have none, EX- 

 STIPULATE. The smaller stipules of the leaflets in com- 

 pound leaves, are called STIPELS. 



295. Stipules sometimes, but rarely, develope buds 

 in their axils. They are subject to the same laws of 

 form and venation, and perform, in their degree, the 

 same offices as true leaves. They do not occur in every 

 plant; in many they are wanting; but they are quite 

 uniformly present in all plants of the same natural Order. 



BRACTS. 



296. These are certain modifications of the Leaf, 

 which, as they grow near the flower, are often called 

 Floral Leaves ; and they seem to occupy an intermediate 

 rank between the Vegetative and Reproductive Organs 

 They are generally distinguished from the proper leaves 

 by a difference of form and color. They are frequently 

 of brilliant hues, and sometimes constitute the chief 

 beauty of the flower, as in the elegant Painted Cup of 

 our wet meadows, where the large pea-green bracts, tipped 

 with the most vivid scarlet, eclipse and obscure the small 

 inconspicuous flowers, and by a common observer would 

 be mistaken for the flower itself. The same is true of 

 the large white bracts that inclose a cluster of small 



leaves are furnished with stipules, what are they? When not? What ni-o 

 Bracts? What rank occupy? How distinguished from true leaves? How 

 are they frequently ? Instances. How in tho Painted cup ? 



