76 



ESSENTIALS OF VEGETABLE PHARMACOGNOSY. 



or by developing alternately upon differ- 

 ent sides (Pig. 373c) they maintain con- 

 tinuously the general direction of the 

 axis> although it may be in an irregular or 

 sinuous manner. In Figs. 369, 371 and 

 372, the apex of the stem, a, may be seen 

 to each year become erect, producing the 

 aerial stem of that year, the sympodial 

 extension being by means of the branch, 

 b, which will the next season in turn be- 

 come erect and give origin to another hori- 

 zontal branch. 



The term Acaulescent. whil^ mpaninp- 



rooting at the joints; Repent, or ''Creep- 

 ing," when prostrate and rooting at the 

 joints (Fig. 374); Twining, when support- 

 ing themselves by the twining of the stem 

 itself around a support; Climbing, when 

 elevating and supporting themselves by 

 other methods than a twining habit, the 

 principal forms being the Cirrhiferous, 

 when climbing by tendrils (Fig. 356), and 

 Aculeate, when climbing by hooks (Fig, 

 357). 



As to modifications of form of function, 

 stems are subject to a somewhat elabor- 



strictly stemless, can, of course, have no ate classification. 



such application, as all flowering plants 

 possess a stem even before germination 

 occurs. The term is applied to those plants 

 whose stems are so short as not to be- 

 come conspicuous. The stem of such a 

 plant is called a Crown. The term crown 



They may be modified for the purpose 

 of defence, that is into thorns or spines 

 (Fig. 375), although not all thorns or 

 spines are transformed "branches. 

 Branches of this form sometimes remain 

 so permanently, while at other times they 



is also applied to the branching or leafy afterward become foliaceous and develop 



into branches of the ordinary form (Fig. 

 376). 



portion of any stem. A plant possessing 

 a woody and erect stem rising singly to 

 the height of fifteen feet or more is de- 

 nominated a Tree, or Arborescent plant, 

 although the precise application of such a 

 term is impossible. A perennial woody 

 stem which has not these characters is 

 called a Shrub or a Fruticose stem. Very 

 small shrubs appearing on casual inspec- 

 tion as herbs are called Undershrubs or 

 Suffruticose plants. 



As to the direction of their growth and 

 the nature of their support, stems may be 

 Erect, in which case they are erect 

 through their entire length; Ascend- 

 ing, in which case the base for a 



For the purpose of climbing they may 

 become cirrose, that is, converted into 

 Tendrils, The tendril may consist of the 

 apex of the prlmnry stem (Fig. 356), which 

 then usually becomes forced to one side 

 by the contiguous branch, which in turn 

 fulfils the ofiice of continuing the exten- 

 sion of the stem as a sympodium: or one 

 of the branches may become the tendril. 

 In the latter case the tendril will stand in 

 the axil between leaf and stem; in the 

 former it will stand upon the opposite side 

 of the stem from the leaf (for tendrils con- 

 nected with the leaf see following). A 



greater or less distance rests upon the stem may instead become converted into 



ground, the terminal portion becoming 

 erect; Horizontal, in which case they are 

 considered as having no other support 

 than the parent stem, from which they 

 extend at a right angle; Drooping, in 

 which case they are first horizontal, the 

 outer portion becoming pendant; Pen- 

 dant, or "Weeping," when they are pen- 

 dulous from their point of origin or almost 

 therefrom; Decumbent, when at first 

 erect or supported by the parent, the outer 

 portion declined so far as to rest upon the 

 ground ; Reclining, when resting upon 

 some means of support elevated above the 

 earth, as over the tops or branches of 

 other plants; Procumbent, when resting 

 at full length upon the ground without 



a sucking disk, as in the case of Ampel- 

 opsis (Fig, 358). In this case the tip of 

 the branch or stem becomes flattened and 

 attaches itself very tightly to the support- 

 ing surface, so tightly, in fact, that a por- 

 tion of stone or a splinter of wood may be 

 torn from its support before the disk can 

 be made to separate. Plants which grow 

 in the water or in places subject to inun- 

 dation may have portions of their stems 

 inflated into bladdery forms to insure a 

 floatiuK condition. Such structures are, 

 however, more commonly of a leafy na- 

 ture. 



Stems may become modified for the per- 

 formance of the office of leaves. For this 

 purpose the whole stem may become mod- 



