36 



the; cactaceae;. 



Rose's observations. Dr. Zehntner also says it differs from the latter in its more numerous, 

 finer spines, which are of a light orange-yellow color. We find, too, that the radial spines 

 are less spreading, while the centrals are much like the radials, acicular, and not stout- 

 subulate as in the other species, and the flowers appear to be smaller. 

 Figure 41 shows a flower from the type plant. 



13. Cephalocereus leucostele (Giirke). 



Cercus leucostele Giirke, Monatsschr. Kakteenk. 18: 53. 1908. 



Plants normally simple, 2 to 5 meters tall, 4 to 8 cm. in diameter, the joints surrounded by 



peculiar bands or collars of long bristles; ribs 13 to 18, low; spines numerous, white, acicular, the 



lateral ones spreading, the central much longer, 3 to 5 cm. long; flowers borne in a mass of wool 



at top of plant but fruit becoming lateral by the prolongation of the stem ; perianth slightly curved 



-Cephalocereus leucostele. 



Fig. 43. — Cephalocereus sraithianus. 



downward, dull green, with a few small scales, 7 cm. long, opening in the early evening; perianth- 

 segments short, waxy, white, tightly recurved; stamens numerous, included; filaments white, the 

 upper cluster thickly set all over the long throat, very short; the lower cluster few, fixed at top of 

 short tube proper, longer t<han the others, bent in just above their bases forming a knee and pressing 

 against the style; space between the two clusters of stamens short but definite; perianth-tube proper 

 1.5 cm. long; style slender, white, pressed against the upper part of tube; anthers dehiscing soon 

 after the flower expands, appressed against the tube; fruit smooth, longer than broad, 5 cm. long, 

 bluish green, the rind thick, the pulp white; seeds black, tuberculate. 



