Anatomy and Physiology of Baccharis genistelloides 



I>V I-'.I.SIK M. Ktl'lKK 



Baci/taris gciiistcl/ouiis Pcr.s. is an inhabitant of the mountains 

 of Peru, growing in dry places at an altitude of about 1200 me- 

 ters. It has several well-marked varieties which apparently spread 

 north into Ecuador, and south and east into Brazil. The typical 

 form is a slightl)- shrubby plant of extremely peculiar appearance. 

 The leaves are atrophied, being represented by minute scales 

 scarcely more than 2 mm. in length ; and the work of photosyn- 

 thesis is assumed by conspicuous wings which stand at three 

 equal angles from each other. The scales are arranged in three 

 orthostichies, and two wings originate from the base of each .scale. 

 One of these wings runs through only one internode and termi- 

 nates at the margin of the scale below ; the other, in each case, 

 runs through two internodes until it is similarly stopped. This 

 alternation of a long and a short wing in each orthostichy, as 

 well as the fact that the wings (following the phyllotaxy) twist 

 spirally, accounts for the curious appearance of the plant repre- 

 sented in /". /. 



While the shoot is almost uniformly leafless in the upper por- 

 tion, usually one, two, or even several normal leaves are to be 

 found near its base. They are of moderate size, obovate and 

 somewhat thickened (/. 2 and ?). The genus Baccharis is a 

 large, and as far as leaf-form is concerned, a heterogeneous one. 

 The leaves of many species, e.g., B.floribunda and B. trincrvis, 

 are large, thin and smooth ; others, as those of B. alpina and 

 /). inicrop/iy//a, are minute and thickened ; B. apJiylla and B. gra- 

 cilis have only narrow phyllodes ; and, finally, B. genistelloides 

 and B.fastigiata are devoid of foliar leaves. The leaves of sev- 

 eral of the species, however (and it is significant that these are 

 generally South American species), particularly B. dioica and 

 B. cassinaefolia, closely resemble in shape, size and texture the 

 juvenile leaves of B. genistelloides. There is every reason, then. 



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