14 SILVA OF NORTH AMERICA. 
CONSPECTUS OF THE NORTH AMERICAN ARBORESCENT SPECIES. 
CYLINDROPUNTIA. 
Joints of the branches cylindrical, tuk late, with reticulated ligneous skeletons ; spines inclosed in 
loose sheaths ; fruit fleshy, setulose, or occasionally spinescent; seeds marginless, marked by a 
conspicuous narrow marginal commissure. 
Tubercles of the branches full and rounded below the areolz. 
Joints pale olive-colored, easily separable, their tubercles broad, mamillate ; spines yellow ; flowers 
pink; fruit proliferous, usually spineless, often sterile . fog 
Joints green or purple, their tubercles narrow, ovate ; spines white to reddish ee Hee race. , 
fruit yellow, sparingly spinescent, rarely proliferous . oo bob) 
Tubercles of the branches not full and rounded below the areolz. 
Joints elongated, dark green, or purple, their tubercles elongated ; spines brown or reddish brown; 
flowers green, tinted with red or yellow; fruit green, spinescent, rarely proliferous 
CACTACEA. 
1. O. FuLerpa. 
2. O. SPINOSIOR. 
3. O. VERSICOLOR. 
