276 FLORA OF TEXAS. 



scarcely as thick as a quill ; young branches 4"-8" in diam- 

 eter; ribs very little prominent ; areolce l"-2" apart ; radial 

 spines a line long or less; central spine 2 "-3" long; in 

 robust plants the entire spine is brown or black, rigidly 

 erect; flower over 2' long and of the same diameter, open- 

 ing for several days, but only in bright sunshine ; ovart/ 

 and tube covered with very woolly pulvilli in the axils of 

 the reddish scales, with 6-8 long white or black bristles; 

 petals rose-color or purple, 1' long; fruit covered with 

 long wool and black and white bristles. Rio Grande. — Dr. 

 Engelmann and Dr. Poselger. 



C. YARiABLis, Pfeiff. Tall species, 3°-10° high ; full- 

 grown stems 3-4-angled, with few and stout spines; but 

 young shoots with 8 ribs and numerous slender spines ; 

 floicers white, nocturnal ; fruit oval, about 3' long, spinose, 

 crimson externally and internally; seed obliquely obovate. 

 Southern Rio Grande. 



C. Greggii. Root a dirty, large, fleshy tuber, often 4-6' 

 in diameter, and about 6-10' long, generally, producing 

 but one stem 2°-3° high, with erect branches; stem thin 

 at base, rather terete and ligneous, upward 9-12" in diam- 

 eter, usually 4-5-angled. The acute ribs at first sight seem 

 crenulate, the pulvinate areola being separated by a slight 

 depression, and the spines being scarcely visible without 

 close examination; areolce 1"-1J" long; ^^i;ze^ remarkably 

 ehort, and from a disproportionately thick base, only 1' 

 long; the 3 lowest spines are the longest, and run into a 

 fine bristly point, often somewhat curved; ovary 9"-12" 

 long; whole flovjer 6-8' long, about 2y in diameter; 

 bristles at base of the tube 1' -2", or upward 4"-6" ; berry 

 ovate, H' long, 1' in diameter. Stem always triangular, 

 of a reddish-brown color. — Engelmann. 



C. Vasmerii. CalyX'twhQ prolonged; three rows of 

 sepals, the outside row greenish white, segments long and 

 narrow, lanceolate, acuminate; stamens long, the upper 



