THE STEM. 



Fig. 26 



determining 



flower and fruit, but not the leaves ; 

 as the dandelion. Plants with scapes 

 are sometimes called demless j>lc(nts 

 in which case, the scape is considered 

 as a peduncle proceeding from the 

 root. 



a. Peduncle^ or flower-stalk, is hut 

 a subdivision of the caulis or stem ; 

 it bears the flower and fruit, but not 

 the leaves ; when the peduncle is di- 

 vided, each subdivision is called a pedicel. In 

 the species of ^ilants, tlie length of the peduncle is often com 

 pared with the flower. When there is no peduncle or flower- 

 stalk, the flowers are said to be sessile. 



h. Petiole.)' OY leaf-stalk, is a stem supporting the leaf, as the 

 pedimde supports the flower ; it is usually green, and is a part 

 of the leaf itself. The petiole of many plants is somewhat in 

 the form of a cylinder ; the upper surface is rather flattened, 

 the under surface convex. The woody "vascular tissue runs 

 through the petiole as threads or fibers bundled together, but 

 are ramified in the leaf as veins. In most cases, the leaves 

 and fiowers are supported by distinct foot-stalks, but some- 

 times the foot-stalk supports both the leaf and flower. The 

 petiole is often compared with the leaf, as the pedimcle is 

 with the flower, as to its relative length in the different species 

 of plants. 



c. The term frond belongs entirely to Cryptogamous plants ; 

 it is, however, applied to the leaf, rather than the stem ; the 

 leafy part of the fern (Fig. 27, a) is the frond ; this bears the 

 flower and fruit. Linn^us considered the leaves 

 of j^alm-trees as fronds. The stem of the fern 

 (Fig. 27, V) is called a stipe. By observations of 

 geologists it is ascertained that stiped plants were 

 created before cauline ones ; petrifactions of the 

 former being found in the lower formations of 

 the earth, while no remains of cauline plants are 

 found there. The stalk of a fmigus or mushroom 

 is called a stipe. The term is also applied to 

 thread which, in many of the compound flowers, 

 elevates the hairy crown with which the seeds 

 are furnished, and connects it with the seed. 

 Tlius, in a seed of the dandelion, the column 

 (Fig. 28, a) standing on the seed (J) and elevat- 



Fig. 27. 



a. Peduncle — I. Petiole — c. Frond — Which part of the fern is its frond ? — Which the stipe ? — Differ- 

 ence between stiped and cauline plants — Which first formed 1 — Different applications of the term 

 siipp — Stipe of a dandelion seed — Stipe of a mushroom. 



