40 



CLASS-BOOK OF BOTANY. 



further divided into the Caulis, the Trunk, the Vine, the 

 Sucker, the Runner, the Offset and Stolon. 



'.. THE CAULIS is the stem of Herbs, and bears 

 Imtli leaves and flowers. It is chiefly composed of pa- 

 renchyma, and in all temperate climes is annual in dura- 

 tion, as in the Hen-bit, fig. 1. 



~. THE TRUNK is the stem of Trees, and needs no 

 further description, as in the Wax-Palm, fig. 9. 



228. THE CULM is a jointed stem, and distinguishes 

 the family of Grasses, as in fig. 5. 



229. The SCAPE is a stem that springs directly from 

 the root, and bears a flower or flowers, but no leaves, as 

 in the Dandelion, fig. 2. 



230. THE SCCKEU is a branch which, proceeding from 

 a part of the stem just below the surface, rises, and in 

 turn becomes a parent stem, as in the Rose and Mint 

 tribes. The Maize, fig. 4, furnishes a good example, the 

 suckers being seen at 1 and 2, and the jointed culm at 3. 



231. THE RUNNER is a prostrate stem that creeps 

 along the surface of the ground, putting forth leaves and 

 roots in little clusters at its extremities, and thus form- 

 ing new plants, which in due time also extend themselves, 

 and send forth runners. The Strawberry, fig. 10, is a 

 stem of this kind. 



232. THE OFFSET is a short branch, terminated by a 

 rosette of leaves, sent off by the parent plant, and which 

 will, in its turn, strike root and give birth to others. 

 The House-leek, fig. 7, is a familiar example. 



233. A STOLON is a branch curving until it reaches 

 the ground, when it strikes root, and establishes itself, 

 producing new individuals. This habit probably suggested 

 the idea of layering. The Currant and Gooseberry are 

 good examples. The Pandanus odoratus (one of the 

 Screw Pines) has this habit; and at fig. 3 it may bo 

 seen, with its stoloniferous branches curved, and curving 

 to the ground, some of which have already sent up new 

 branches, crowned, like those of the parent tree, with 

 tufts of leaves. 



234. THE VINE is a plant whose stem, being too weak 

 to preserve an erect position, clings to a firmer body for 

 support. When the plants ascend by means of tendrils, 

 they are called Climbers, as in the Grape. In the 

 Clematis, the leaf-stalk performs the office of a tendril ; 

 while in the Pea and Vetch tribes, the tendril is a pro- 

 longation of the summit of the leaf-stalk. 



235. TWINERS' are plants that ascend by winding 

 round some body which serves as a prop ; and there is in 

 every species a determined mode of twining, from which 



Principal aUm-forroa, define and deacrlbe each. When planU ascend by m.-an 

 uf undrlU, what an they? When they wind round a prop? What cflecU when 

 a twIalofaUm la turned frc.ni In eonmr Olri- example*. 



it cannot be diverted, so long as its vital energy is not 

 seriously impaired. In fig. G, which represents the 

 (in -.it Biiuhu-cil, the convolutions are from left to rifrht ; 

 and in fig. 8, the Hop, they are from right to Iri't. 

 From its proper and natural mode of ascent a twining 

 stem cannot be diverted. If trained in an opposite 

 timi, it will repeatedly make sharp angles and cur\ 

 order to restore itself, until it becomes exhausted by its 

 efforts to preserve this great law of Nature. 



236. CLEAVERS. Another class of plants ascend 

 neither by means of tendrils nor by convolutions, but by 

 the roughness of their surface, which tenaciously aillnTrs 

 to the supporting body ; and the habit is distin<nii.-li<'il 

 in the common name of a large genus of plants (Galin>), 

 which are popularly known as Cleavers. One of this 

 curious family is seen at fig. 1 1. 



237. RECLINING STEMS, are those which arc too 

 weak to sustain themselves in an erect position ; and 

 they receive different names, according to their degrees 

 of prostration. ' They are 



(1) ASCENDING, when the stem rises obliquely from 

 the base ; 



(2) DECUMBENT, when the stem trails along the 

 ground, rising at the extremity, as in the common Five- 

 finger; 



(3) PROCUMBENT, when it runs lightly along tin- 

 ground; and 



(4) PROSTRATE or RUNNING, when it keeps close to 

 the surface, sometimes burrowing beneath the ground. 

 Of the eleven forms of the stem represented in Plate IX., 

 four are Endogens, and the remainder Exogens. 



CHAPTER XVII. 



THE STEM SUBTERRANEAN FORMS I 



238. ONE of the results of a closer study, and more 

 accurate observation, has been the discovery that, as a 

 general law, the Root sends forth only naked branches, 

 and therefore produces no buds. Bulbs, tubers, and 

 several other subterranean modifications of the growing 

 axis, are for this reason separated from Root-forms, and 

 they are now ranked among stems. By this arrangement, 

 both the Scaly and Creeping Roots of the old Botanists 

 are now considered as Stems. 



239. The principal subterranean modifications of tho 

 Stem are, the Tuber, Conn, Rhizoma, Bulb, and Creeper 



240. TUBER. This is formed by the terminal bud ol 



General Mibjecl. Why are theM tenanted from Root-fornu f Wht 

 jjrold Botanbu? Why Incorrectly ? Principal Subterranean ModlAoallonr. 

 Da&na and deacrlbe each. 



