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 
ce corolla-lobes all depressed, the upper somewhat exceeding the lower; 
sepals ample, equaling or longer than the hypanthium; flowers solitary, on long 
sets peduncles 
ypanthium ‘hicbbaate 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 kn 
1. Anther-tube iu except ‘isa terminal bru 
a. Sepals triangular-subulate, 4 mm. long, ae shorter than the hypan- 
thium. 
I. SIPHOCAMPYLUS TUNARENSIS et 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. ; 
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. 
