OPUNTIA. 79 



Dr. Rose observed a single plant infested by Loranthus apliyllus, the parasite which is 

 so abundant on Cereus chilocnsis. 



Opuntia heteromorpha Philippi (Anal. IMus. Nac. Chile i8gi' 2 : 28. 1891) we refer here 

 on the authority of Schumann, but we have seen no specimens, the type specimen being 

 missing from the Philippi herbarium in Santiago; it was collected at Chiquito, Tarapaca, 

 Chile. 



Dr. Weber thought that Opitntia tcgclliii belonged here, but we have referred it to 

 0. subulata. 



Opuntia carrizalensis Philippi is only mentioned by Schumann (Gesamtb. Kakteen 

 Nachtr. 152. 1903). It is doubtless to be referred here. 



Plate xvi, figure i, is from a plant collected by Dr. Rose at Vallenar, Chile, in 1914. 



Series 13. CLAVATAE. 



Here we include nine prostrate or spreading, low species, natives of the southwestern United 

 States and Mexico, characterized by clavate joints and by sheathless spines, although rudimentary 

 sheaths have been observed on young spines in some of the species; they appear to form a transition 

 between the subgenus Cylindropuntia and the South American subgenus Tcphrocactus, from which they 

 differ essentially in having clavate joints. 



KEY TO SPECIES. 



Spines flattened. 

 Stems very stout. 



Stems hardly clavate; ovary very prickly . 46. 0. im-iila 



Stems strictly clavate; ovary only slightly prickly ... 47. O. slanlyi 



Stems more slender and weak. 



Spines brown, slender, long (4 to 6 cm. long) . . .48. 0. schottii 



Spines stout, white, when old very flat. 



Bristles on ovary and fruit white . . 49. 0. clavata 



Bristles on ovary and fruit brown ... 50. 0. parislrii 



Spines terete, elongated, and flexible, or the central ones somewhat flattened. 

 Flowers pinkish or purple. 



Bristles on ovary numerous, brown .51.0. pulchella 



Bristles on ovary few, white .. . 52. 0. vilis 



Flowers yellow. 



Spines comparatively short, swollen at base. . . 53. 0. bulbispina 



Spines long and flexible, not swollen at base. . 54. O. grahamii 



46. Opuntia invicta Brandegee, Proc. Calif. Acad. II. 2: 163. 1889. 



Plants growing in large clusters 2 meters in diameter and 2 to 5 dm. high, with many ascending 

 or spreading branches; joints obovoid to clavate, dark green, 8 to 10 cm. long, strongly tuberculate; 

 tubercles large, flattened laterally, 3 to 4 cm. long; areoles large, i to 1.5 cm. in diameter; leaves 

 linear, 8 to 14 mm. long, reddish, curved, acute, deciduous; spines very formidable, when young 

 reddish or purple with carmine-red bases, chestnut-brown at tips and grayish between, but in age 

 dull in color; radial spines 6 to 10; central spines 10 to 12, much stouter than the radials, strongly 

 flattened; wool white; glochids few, white, 2 to 4 mm. long; flowers yellow, 5 cm. in diameter; sepals 

 ovate, acuminate; ovary 2 cm. in diameter, almost hidden by the numerous reddish, acicular spines; 

 seeds yellowish, 2 mm. broad. 



Type locality: About San Juanico, Lower California. 



Distribution: Central Lower California, at low elevations. 



Mr. Brandegee has called attention to the strong resemblance in habit of this species 

 to some of the species of Echinocereus, and Dr. Rose states that when he first saw it he 

 supposed it to be some strange Echinocereus. It grows in great tufted masses and does 

 not suggest in the remotest degree any of our North American opuntias. The species 

 clearly belongs to Engelmann's series Clavatae, where it was placed by Schumann, who 

 associated it with 0. cereiformis, but it is undoubtedly much nearer to 0. stanlyi. So far 

 as we know, the plant has never been in the trade ; it does not succeed well in cultivation. 

 Considerable living material was brought back by the Albatross in 1911, most of which was 

 sent to the New York Botanical Garden ; but some of the plants were sent to collections at 

 St. Louis, Washington, and Los Angeles. 



Illustration: Cact. Journ. i: February. 



