Two new species of Opuntia 
BERNARD MACKENSEN 
From the writer’s studies of Texas cacti, extending over several 
years, he has been able to ascertain that there are still a number 
of undescribed species and varieties among the numerous Texas 
representatives of that interesting family. It may seem strange 
that a field so often tramped over by botanical collectors should 
| still yield a number of new though comparatively common forms, 
especially when these belong largely to the conspicuous opuntias. 
The explanation of this fact is suggested by the writer’s own expe- 
rience in recognizing and differentiating new species and varieties. 
It was only after keeping the native opuntias, growing all about 
him, under critical observation for one or more years, and making 
careful notes, that the writer had revealed to him the presence of 
undescribed forms. In one case it was not until the maturing of 
the fruit, which is very characteristic, that the writer was able to 
make out a clear case of a new species. The transient collector 
4 would probably have confounded this with some other species, 
: unless he had perchance visited the locality while the plants were 
| in fruit. 
Among the new forms mentioned are two which the writer has 
characterized as follows: 
4 Opuntia leptocarpa sp. nov. 
Plants with somewhat fleshy, terete, or sometimes thick- 
tuberous, roots: stems mostly ascending, rarely 5 dm. high; joints 
thin, obovate to oval and elliptic, somewhat glaucous while young, 
deep green when older, or paler in age, mostly 1 to 2 dm. but some- 
times 2.5 dm. long, with subulate leaves 5 to 8 (or sometimes 10) 
“mm. in length: areoles remote, rather small, filled with reddish 
4 long and growing dirty brown with age, the lower areoles usually 
; naked, the upper bearing I to 4 or sometimes 5 unequal spines, or 
4 on some joints mostly spineless; spines whitish, light brown, 
: or mottled, slender, 1 to 3 cm. long or sometimes longer, flattened 
or nearly terete, twisted, spreading, or sometimes the lowest spine 
of an areole much reflexed: flowers yellow with a pale reddish 
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