78 



ESSENTIALS OF VEGETABLE PHARMACOGNOSY. 



ready described, and those connected with 

 leaf attachment, to be described further 

 on, should be studied. 



Besides the above stem-forms, which 

 admit of ready classification, we have a 

 large number of modifications to effect 

 special purposes which must be consid- 

 ered individually. As these possess but a 

 slight interest in relation to pharmacog- 

 nosy we refer the interested student to 

 general works on botany. 



An important office of the stem is the 

 storage of nutriment, AH stems perform 

 this office to a greater or less extent, but 

 some are esi>ecially modified in form for 

 the purpose. Of these we have already 

 referred to special rhizomes and tubers. 

 It remains, then, only to consider the va- 

 rious forms of the bud, including in this 

 term all forms of the bulb. A bulb which, 

 like the onion (Fig. 380) has its fleshy 

 thickened leaves in the form of broad 

 sheathing organs, seen upon transverse 

 section in the form of concentric rings, is 

 called Tunicated or Coated. Those like 

 the lily (Fig. 381), in which these leaves 

 appear in the form of narrower project- 

 ing scales, are called Scaly. When in 

 the axils of the scales we find smaller or 

 secondary bulbs or buds it is a Compound 

 bulb. When the texture of a bulb is so 

 dense that its leaf-elements are not con- 

 spicuous it is designated a Solid bulb- 

 When it is still more dense, as in the case 

 of the gladiolus (Fig. 382), so that the 

 leaves are not to be distinguished by 

 ordinary methods, it is a Corm. In some 

 plants the axillary bulbs, instead of oc- 

 curring in the axils of the bulb-leaves, 

 occur higher up in the axils of the or- 

 dinary foliage leaves, as in the case of 

 the tiger lily (Fig. 383). Their true na- 

 ture as buds is in this case conspicuously 

 shown, and they are sometimes spoken 

 of as Bud-bulbs. In other related plants 

 similar bulbs are densely aggregated in 

 a terminal umbel looking like an inflores- 

 cence, as in some species of onion (Fie 

 384). ^' 



Buda proper admit of an elaborate classi- 

 fication, which, although not of such in- 

 terest in pharmacognosy as to warrant 

 its study in this phice, is of fundamental 

 importance in systematic botany, and fur- 

 nishes a key to many problems which are 



otherwise very abstruse. The study of 

 buds is called Vernation, and that of the 

 arrangement of the leaves composing 

 them Praefoliation. In general the ar- 



rangement of leaves in the bud admits of 

 the use of terms similar to those applied 

 to the parts of the perigone in a similar 

 state. 



Buds may be classified as to their 

 structural form, their position, and parts. 

 A winter bud which protects itself by 

 specially developed scales is known as a 

 Scaly bud; one which does not, a Naked 

 bud. A bud consisting only of leaves is 

 a Leaf bud; one only of a flower, a 

 Flower bud; one consisting of both, a 

 Mixed bud. Solitary buds occurring in 

 the axil of the leaf and developing at the 

 regular time are called Normal buds. 

 Any buds in addition to the Normal bud, 

 occurring in the leaf axil, are called Su- 

 pernumerary. They may be situated 

 above or at the side of the normal bud. 

 ihe normal bud is sometimes situated a 

 httle above the actual axil, in which" case 

 It IS called Supra-axillary. All the buds 

 so noted are denominated Lateral, in con- 

 tradistinction to the single terminal bud, 

 but it IS to be noted particularly that 

 buds lateral as to their origin may be- 

 come terminal through the e&eets of 

 sympodial growth. Buds which develop 

 at other points than the apex or axil— as, 

 lor instance, from an internode, a leaf, 

 or even from a root, as well as those of 

 axillary origin, but developing out of their 

 regular order— are called Adventitious. 

 Ihe latter form of adventitious buds, re- 

 sulting from retarded development, are 

 known as Latent buds. 



