14 Proceedings of the Biological Society of Washington. 



except at very apex of joints where in extreme cases they may be 15 mm, 

 in length ; spines the first year 2 to 4, dark-brown except the lower down- 

 ward sloping shorter ones, 15 to 20 mm. long, which are white, the others 

 porrect and the longest often 6 to 8 cm. in length ; the second year fading 

 to light-brown or yellow flesh-color, becoming white with age and increas- 

 ing slightly in numbers, some of those on old wood very much flattened 

 and twisted, annular at the base, especially the second season; flowers 

 yellow with red centres, filaments yellow but greenish at base, style white, 

 stigma large, subglobose, light-green ; fruit purplish-red with a deep 

 bloom and much lighter colored within, the rind simply streaked with 

 red and pulp slightly mottled, only at complete maturity is the color of 

 the rind and pulp diffused and light-red, areoles small, elongated, ^ to 

 2 mm. long when wool is removed but before removing wool 3 mm. long 

 and broadly oval, dull, dark gray, tawney with wool protruding 1 mm. 

 and the brown, unequal spicules 2 mm. longer than the wool, fugacious 

 spines irregular, 6 to 11 mm. long, lighter colored, often brownish to 

 yellowish-white at maturity. 



The species is easily recognized by the densely glaucous aspect of plant 

 and fruit and shape of its joints. It has nearly as much bloom as the 

 0. robusta group of the Mexican highlands. The type was collected 

 between Crozier and Hackberry, Arizona, the first of May, 1912, under 

 my inventory number 10555. It has been observed in several situations 

 in that general region and one other collection has been made and cul- 

 tivated. 



Opuntia expansa sp. nov. 



A low, spreading species with long, radiating arms, 50 cm. high and 

 having a spread with us now of 160 cm. but in natural habitat the radiating 

 arms often 130 cm. in length and the entire plant 2)^ to 3 meters or more 

 in diameter and reaching an extreme height of one meter, main arms 

 radiating and resting on edge ; joints obovate, at first glaucous but losing 

 its plumosity and becoming yellowish-green with age, about 11 to 13 by 

 20 to 22 cm., rounded above and contracted below into a more or less 

 stipitate base; areoles broadly obovate to subcircular often 6 mm. in 

 length on edges but commonly only 4 mm. on sides of joints, brown 

 turning dirty black, becoming very prominent, subcircular and often 3 

 mm. high on old joints; spicules yellow to light-brown, in a compact 

 tuft above, scarcely as long as the protruding wool with a few scattering 

 bristles, more numerous and longer in age especially on edges toward 

 apex of joints, sometimes 8 mm. long and always yellow in situ; spines 

 light-brown at base, white distally, toward apex of two-year old joints 

 there are commonly 4 to 5, the lower being white, 1 to 1)4 cm. long, the 

 next situated directly above usually 3 cm. long, white throughout or 

 dirty yellow to brownish at base, the other 2 or 3 slightly shorter and 

 more deeply colored, commonly brownish below and yellowish distally 

 but color variable; flowers 8^ cm. in diameter, yellow with dull red 

 centre, the red coloration streaking upward through the veins late in the 

 day, buds with decidedly glaucous-greenish sheen and scales lax ; fruit 



