1 86 



THE CACTACEAE. 



FIG. 227 Opuntia megacantha on Lanai, Hawaiian Islands. 



Type locality: In Mexico. 



Distribution: Much cultivated in Mexico; grown also in Jamaica and southern Cali- 

 fornia and escaped from cultivation in Hawaii. 



This species was originally described by Salm-Dyck essentially as follows : Erect and 

 of the size of O. decmnana; joints 17.5 cm. long by 7.5 cm. broad and 2.5 cm. or more 

 thick ; areoles close together, filled with gray wool ; 

 glochids brownish, becoming blackish ; spines 7 to 

 10, white, unequal, acicular, somewhat radiating, 

 the longest one deflexed, 5 cm. long; flowers not 

 known; leaves small, reddish. 



Opnntia megacantha trichacantha Salm-Dyck 

 was given as a synonym of this species by Forster 

 (Handb. Cact. 486. 1846), but was never pub- 

 lished. 



Opuntia tribuloides Griffiths (Monatsschr. 

 Kakteenk. 23: 137. 1913), according to the de- 

 scription, is of this relationship. 



This is the chief Mission cactus. It is the 

 one from which the best varieties of edible tunas 

 are obtained and is one of the commonest culti- 

 vated opuntias in Mexico, having numerous forms, 

 many of them bearing local names. 



Illustrations: Ariz. Agr. Exp. Sta. Bull. 67: 

 pi. 8, f. 2; Rep. Mo. Bot. Gard. 19: pi. 24, both as 

 Opuntia castillae. Rep. Mo. Bot. Gard. 22: pi. 4, 

 5, these two as Opuntia incarnadilla; Amer. Journ. 

 Bot. 4: 572. f. 6. 



Plate xxxn, figure 4, represents a flowering 

 joint of a plant in the same collection received 

 from Fairmount Park, Philadelphia, in 1905. 

 Figure 226 is from a photograph of a plant in 

 the collection of the New York Botanical Garden; p, G 22S ._ Opuntia megacantha. X<M- 



