192 Gleason: Centropogon and Siphocampylus 



In both genera, the species show unusually clear lines of 

 demarcation, and are separated by characters of the hypanthium, 

 corolla, anther-tube, inflorescence, foliage, and pubescence. 

 But since these characters show little correlated variation, the 

 delimitation of species-groups and the determination of intragen- 

 eric relations become a matter of some difficulty, which is 

 increased rather than lessened by extending the study to other 

 South American countries. 



Both genera find their center of distribution with the greatest 

 number of species in the Andean region of northwestern South 

 America from Colombia to Bolivia. Other South American and 

 all North American forms are to be referred to this center for 

 their geographical origin. 



Conspectus of the species 



I. Corolla relatively short and broad, but large, the tube equaling or little exceeding 

 the lobes, thick and firm in texture, white, yellowish, ochroleucous, or dull 

 purple; corolla-lobes all depressed, the upper somewhat exceeding the lower; 

 sepals ample, equaling or longer than the hypanthium; flowers solitary, on long 

 axillary peduncles. 

 A. Hypanthium turbinate, broader than high when pressed, prominently ribbed 

 anther-tube glabrous, or pubescent only on the connectives; corollas white 

 or cinereous, the lobes equaling or exceeding the tube in length; fruit cap- 

 sular, so far as known. 

 i. Anther-tube glabrous, except the terminal brush. 



a. Sepals triangular-subulate, 4 mm. long, much shorter than the hypan- 



thium. 



1. Siphocampylus tunarensis A. Zahlb. Bull. Torrey Club 24: 



376. 1897. 

 The specimen in the herbarium of the New York Botanical 

 Garden is fragmentary and does not permit the verification of 

 Zahlbruckner's detailed description, but is sufficient to demon- 

 strate its close relation to the following three species. Fruit has 

 not been seen. 



b. Sepals linear, equaling or exceeding the hypanthium in length. 



2. Siphocampylus Rusbyanus Britton, Bull. Torrey Club 19: 



372. 1892. 

 Sepals 10 mm. long by 2 mm. wide; leaf-blades ovate-elliptic, 

 5-9 cm. long, acute or obtuse, rugose above, reticulate beneath, 

 abruptly narrowed into a petiole 10-15 mm. long. 



