172 MISSOURI BOTANICAL GARDEN. 



trunks 



bonelike, changing abruptly to white or often yellowish or even trans- 

 lucent which in turn fades into various degrees of reddish brown or 

 even nearly black at base; flowers yellow to deep orange-red; fruit 

 reddish-purple. 



This species has been cultivated several years by Pro- 

 fessor E. 0. Wooton in whose honor it is named. It is one 

 of the most striking of our native opuntias and is easily 

 recognized by its large joints, pointed at both ends like 

 0. occidentalis, and exceedingly formidable, showy spines 

 which resemble those of Opuntia tricolor more closely than 

 any other species with which I am familiar. 



The description given above is taken from a cultivated 

 plant in the third year of its development, supplemented 

 by notes upon flowers and fruits grown at Messilla Park, 

 N. M., by Professor Wooton, who collected the species orig- 

 inally in the Organ Mountains of New Mexico. The type 

 bears my collection No. 9171 which was prepared May 4, 

 1910, from a cultivated plant the cutting for which was 

 secured in April, 1908, from Professor Wooton's collection. 

 The species was originally collected under Professor Woo- 

 ton's No. 3030. The plants from which the above descrip- 

 tion was drawn bore but one flower bud this year, the third 

 season from planting. — Plate 26, upper figure, and Plate 27. 



Opuntia atrispina sp. nov. 



Plant 7 to 10 dm. high and 12 to 15 dm. in diameter or often 

 smaller, the main branches spreading with edges on the ground or 

 ascending, the secondary branches mostly erect; joints obovate, 

 rounded above to sub-circular, mostly slightly raised at areoles, about 

 11 by 15 cm. and 1 cm. thick, yellowish green; areoles obovate, or 

 on young joints mostly elongated and raised below, about 5 mm. long 

 and 25 mm. apart; spicules yellow, prominent, unequal, occupying a 

 large triangular area in upper part of the areole, but finally scattered 

 throughout its entire area but more numerous above, 6 to 12 mm. 

 long, increasing with age; spines jet black to reddish brown at base 

 with yellow tips, the transition between the two colors being quite 

 abrupt, but the proportion of the two colors varying tremendously in 

 different individuals, mostly one large, sub-erect one, 25 mm. long and 

 one smaller, recurved one about 13 mm. long immediately below it 

 and 2 shorter beside and a little below the latter about 6 mm. long; 

 scattered among the spines are a few fugacious, reddish brown spic- 



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