h5 



OF THE STEM. 



5th. Petiole, or leaf stalk, is a kind of stem, like a fulcrum, sup- 

 porting the leaf, as the peduncle supports the flower ; it is usually 

 green, and appears to be a part of the leaf itself The petiole of 

 many plants is somewhat in the form of a cylinder ; but the upper 

 surface is rather flattened, the under surface convex. You will find 

 this remark useful, in distinguishing the foot-stalks of compound 

 leaves from young branches, with which they are sometimes con- 

 founded. In most cases, the leaves and flowers are supported by 

 distinct foot-stalks, but sometimes the foot-stalk supports both the 

 leaf and flower. The Petiole is often compared with the leaf, as the 

 peduncle is with the flower, as to its relative length, in the different 

 species. 



6th. Frond. (Fig. 27.) The term 

 frond, belongs entirely to Cryptoga- 

 mous plants. This term however is ap- 

 plied to the leaf rather than the stem ; 

 in this sketch of the fern, the leafy part, 

 6, is the frond ; this bears the flower and 

 fruit. Linnaeus considered the leaves 

 of palm-trees as fronds; we shall here- 

 after remark upon the different internal 

 structure of their stems from those of 

 the oak and other plants Mhich are 

 termed cauline, because their stem is a 

 caulis. Plants with fronds are mono- 

 cotvledonous. 



7th. Stipe. The stem of the fern (Fig. 27, a,) is called a stipe. By 



observations of geologists it is ascertained that stiped plants were 



created before caidine ones; petrifactions of the former being found 



in the lovv'er formations of the earth, while no remains of cauline 



Fi?. 2S. plants are ever found there. The stalk of a fungus or 



mtijiji' mushroom is called a stipe. The term is also apphed to 



miim^ the slender thread, which in many of the compound flow- 



-^ ^ ers, elevates the hairy crown with which the seeds are 



furnished, and connects it with the seed. Thus, in a seed 



of the Dandelion, which is here represented, the column 



(Fig. 28, a,) standing on the seed (6,) and elevating the 



down (c,) is the stipe. 



Here is a mushroom with the cap (Fig. 29, d,) 

 elevated on its stipe (e.) 



Branches. The stem is either simple, or divided 

 into branches. The branches are parts of the 

 plant which proceed immediatety from the 

 trunk ; the division of these are called branch- 

 lets ; a diminutive appellation, which means a 

 little branch. These parts resemble, in their 

 formation, the trunk or stem, which furnishes 

 them ; the branch may be considered as a tree, 

 implanted upon another tree of the same species. 

 Branches sometimes grow without any apparent 

 order in their arrangement; sometimes they 

 sometimes alternate; and sometimes, as in the pine, 

 series of rings around the trunk. Some branches 



are opposite, 

 they form a 



Peduncle— Petiole — Frond— Which part of the fern is its frond ?— Which the stipe? 

 —Difference between stiped and cauline plants— Which first formed ?—Diflx'rent ap- 

 plications of the term stipe— Stipe of a dandelion seed— Stipe of a mushroom— 

 Cranches— Eranchlels— Varir-us appearances of branches. 



