196 VEGETABLE ORGANOGRAPHY. 



the true Dragon's Blood, analogous to .that which is 

 extracted from Dracoena Draco. 



The stem of the Liliacea?, which, considered in Dra- 

 coena and Yucca, hardly differs from that of the Palms, 

 and is elevated to the height of a tree or shrub, presents 

 in other species an entii'ely different appearance : thus, 

 the stem of Aloe, of Anthericum frutescens, &c. is of a 

 woody texture, but attains a less size than the preceding, 

 forming little shrubs or under-shubs. In the Smilaceas, 

 Dioscoreag, and several Asparagi, the stem is very long, 

 but slender, and more or less twining, without differing 

 however from the preceding, more than the climbing 

 Convolvuli do from the shrubby ones : in others — as, for 

 example, the Lily, Fritillai-y, Pine- Apple, &c., the stem 

 remains herbaceous, cylindrical, long, upright, firm ; and 

 does not differ from the woody stems which we have 

 mentioned, except in its texture, that is to say, just as 

 the herbaceous Leguminosae differ from the trees of the 

 same family. In all these cases the stem is a distinct 

 organ, and, when it is perennial, is terminated by a 

 single bud, which is larger in proportion as the stem is 

 less branched. But in some species which are called 

 bulbous, the stem is very short, being reduced to an 

 orbicular plate concealed underground, and surrovmded 

 by the persistent scales of the terminal bud ; this we see 

 in the Tulip, Hyacinth, Garlic, &c. "We find all the 

 intermediate degrees of length between the arborescent 

 stems mentioned just now, and the subterranean ones of 

 bulbs ; thus, among the species of Crinum, some have 

 the stem elongated, and rising above the ground a foot 

 or more in height; and there are others with it short and 

 buried in the earth ; in the genus Allium, most of the 

 species of which have the plate of the bulb short and 

 scarcely perceptible, there are some in which it takes 

 the appearance of a true stem, although it remains 



