60 MORPHOLOGY. 
vided with’roots, and stand above the surface of the soil or are 
half or entirely imbedded therein. The axis of the bulb is mostly 
flat, disk-like (Fig 1, 7). The only officinal bulbs of the U.S. 
Pharmacopeia (1880) are Scilla and Allium. 
By the accumulation of reserve substances, aid is given to the 
respective plant, corresponding to the climatic conditions, ren- 
dering it capable of attaining its full development in the shortest 
time and during the most favorable periods of the year. 
A Corm (Cormus) is intermediate between the tuber and the 
bulb. Itisa bulbo-tuber or bulbodium tunicatum, or atrue tuber, 
which is provided with under-leayes and enveloped by them (Col- 
chicum). 
The thickened, and for the most part subterranean organs of 
Fig, 1.—Median longitudinal section through a tunicated bulb. 1, the disk-shaped, 
expanded axis; v, the bud; t, under-leaves; 7, roots. _ 
the stem, above described, lead us to the consideration of the 
proper organs of the stem, growing above ground. 
Stem structures are formed either by the development ot 
the stem portion of the plumule of the germinating plant (see 
below), or as lateral shoots on other organs of the stem, in the 
axils of leaves. 
That portion of the stem which lies between the point at 
which the cotyledons are affixed and the point of attachment of 
the root is called the hypocotylous' member, caulicle or radicle. 
This remains mostly ;short (in the Hypogee,” i. ¢., those 
‘*Txé under, and xorvAndar (cotyledon) cavity. 
* "Tmo under, and yara earth. 
