Cactus Family 259 



with an axillary pulvinus, which is usually clothed 

 with soft wool intervened with barbed bristles at the 

 upper edge and usually bearing spines at the lower edge. 

 Flowers developed from the bristle-bearing part of the 

 pulvinus, with rotate corollas. Ovary covered with 

 caducous leaves bearing axillary wool and often bristles 

 and spines. Fruit dry or succulent. Seeds large, flat- 

 tened and discoid, often margined, whitish ; cotyledons 

 foliaceous, curved about the endosperm. 



* Joints flattened. PRICKLY PEAR. 



1. O. Lindheimeri occidentalis (Engelm.) Coult. Erect and 

 spreading, 1-3 m. high, usually forming thickets; joints often 3 

 dm. long and 2 dm. wide; pulvini remote, about 4 cm. apart, 

 with very fine closely set bristles, 1-3 white (dusky at base) de- 

 flexed spines; fruit sour, very juicy; seeds 5-6 mm. broad, their 

 margins crenulate. 



Frequent in our valleys and foothills from Los Angeles eastward. 



2. O. Lindheimeri littoralis (Engelm.) Coult. Erect or spread- 

 ing, about 10 dm. high ; joints often 30-45 cm. long and 20-25 cm. 

 wide; pulvini usually about 2.5 cm. apart; spines straw color 

 (dusky at base), deflexed, slender; seeds 3-4 mm. broad, their 

 margins undulate. 



Frequent on bluffs along the seashore. 



** Joints cylindric. 



3. O. Bernardina Engelm. Stems erect or nearly so, loosely 

 branched, slender, 6-15 dm. high, with reticulate wood; joints 

 cylindric, 7.5-30 cm. long, with slender oblong tubercles, 2.5-3 

 cm. long ; pulvini with a dense row of very short, dark, more or 

 less persistent bristles at upper edge ; spines yellow, the sheathed 

 ones 4-5, 1-3 cm. long, the lowest longest and usually reflexed; 

 and 4 appressed short radial ones mostly on lower edge of pul- 

 vinus; flowers greenish yellow, tinged with red without, 2.5-4 

 cm. broad; fruit ovate, less than 2.5 cm. long, at length dry; 

 seed flat, 6 mm. broad, with a channeled commissure and con- 

 spicuous persistent funiculus. 



Frequent on the interior plains east of Monrovia; also in the Santa Clara 

 Valley, Ventura County. 



