760 TREES OF NORTH AMERICA 



juices of some of the Mexican species, and the fruit of several species is refreshing and is con- 

 sumed in considerable quantities in semitropical countries. The large-growing species with 

 flat branches are employed in many countries to form hedges for the protection of gardens 

 and fields; and the branches saturated with watery juice are sometimes stripped of their 

 spines and bristles and fed to cattle. 



Opuntia is the classical name of some plant which grew in the neighborhood of the city 

 of Opus in Bceotia. 



CONSPECTUS OF THE ARBORESCENT SPECIES OF THE UNITED STATES. 



Tubercles of the branches full and rounded below the areolse. 



Joints pale olive color, easily separable, their tubercles broad, mammillate; spines yellow; 

 flowers pink; fruit proliferous, usually spineless, often sterile. 1. O. fulgida (H). 

 Joints green or purple, their tubercles narrow, ovoid; spines white to reddish brown; 

 flowers purple; fruit yellow, sparingly spinescent, rarely proliferous. 



2. O. spinosior (H). 



Tubercles of the branches not full and rounded below the areolae; 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. 



3. O. versicolor (H). 



1. Opuntia fulgida Engelm. Cholla. 



Leaves light green, gradually narrowed to the acuminate apex, |'-1' long. Flowers 

 appearing from June to September, the earliest from tubercles at the end of the branches 

 of the previous year the others from the terminal tubercles of the immature fruit devel- 

 oped from the earliest flowers of the season, 1' in diameter when fully expanded, with ovaries 

 nearly 1' long, 8-10 obtuse crenulate sepals, 5 erect stigmas, and 8 light pink petals, those 

 of the outer ranks cuneate, retuse, crenulate on the margins, shorter than the lanceolate 

 acute petals of the inner ranks, the whole strongly reflexed at maturity. Fruit proliferous, 



Fig. 683 



oval, rounded, l'-lj' long and nearly as broad, more or less tuberculate, conspicuously 

 marked by large pale tomentose areolse bearing numerous small bristles, usually spineless or 

 occasionally armed with small weak spines, hanging in pendulous clusters usually of 6 or 7 

 and occasionally of 40-50 fruits in a cluster, one growing from the other in continuous suc- 

 cession, the first the largest and containing perfect seeds, the others frequently sterile, dull 

 green when fully ripe, with dry flesh, falling usually during the first winter or occasionally 

 persistent on the branches during the second season, and then developing flowers from the 

 tubercles; seeds compressed, thin, very angular, yV~' m diameter. 



