OF THE STEM, 



41 



If a plant be watered by any coloured liquid, the stem will, in time, 

 ehow that this fluid has ascended into it. There is also in the stem 

 a set of vessels to carry downward the juices, which have passed 

 through pecuhar processes in the leaves of the plant. 



But of the circulation of fluids in the vegetable substance we shall 

 speak more particularly hereafter. Our present object is, to describe 

 the external appearance of the vegetable organs, and not their in- 

 ternal structure ; or, in other words, it is the anatomy and not tho 

 physiologi/ of plants, which we are now attempting to explain. 



The different kinds of stems have been divided 

 into seven classes, as follows— 



Caulis* or proper stem, Ciibn, Scape, Peduncle, 

 Petiole, Frond, and Stipe. 



1st. Caidis, or proper stem, is such as is seen in 

 forest trees, in shrubs, and in most annual plants. 

 The caulis is either simple, as in the White lily ; or 

 branching, as in the Geranium. The branching is 

 the more "common form. You have here (Fig. 24) 

 the representation of a caulis, or proper stem (a ;) 

 ■ 24. a peduncle, or flower stalk (6;) and a 'petiole, or 

 leafstalk (c.) 



2d. Cidm, or straw, (Fig. 25,) is the kind of stem 

 which you see in grasses and rushes. The culm 

 is either without knots, as in the Bulrush, jointed or 

 knotted, as in Indian corn, genicidated, or bent like 

 an elbow, as in some of the grasses. Those culms 

 which are bent, are also knotted, though they may 

 be knotted without being bent. 

 The Bamboo, Sugar Cane, and 

 various species of Reeds, have 

 stems of the culm kind ; some of 

 them, particularty the Bamboo, 

 are known to attain the height of 

 forty feet. 

 3d. Scape, (Fig. 26, a, a,) a stalk 

 springing from the root, which bears 

 the flower and fruit, but not the leaves : 

 the Dandehon, the Cowshp, and the 

 Lily of the Valley. Plants with scapes 

 are sometimes called stemless plants ; in 

 this case, the scape would be consider- 

 ed as a peduncle proceeding from the 

 root. 



4th. Peduncle, or flower stalk, is but a 

 subdivision of the cauUs or stem; (See 

 Fig. 24, b ;) it bears the flower and fruit, 

 but not the leaves ; when the peduncle is divided, each subdivision 

 is called a pedicel. In determining the species of plants, we often 

 consider the length of the peduncle, compared with the flower ; as, 

 whether it is longer or shorter. When there is no peduncle or flower 

 stalk, the flowers are said to be sessile. 



* This kind of stem is by the French called tige; the i should be sounded like e, 

 the f soft lilie.;', as in teje. The word Caiilis is from the Greek Kaulos, a stem. 



Division of stems— Caulis— Culm- 



