212 THE CACTACEAE. 



Dr. and Mrs. Rose collected, July 9, 1914, at Matricaria, much higher up the mountains 

 than Santa Clara, two other specimens (Nos. 18652 and 18653); i n the field these seemed 

 different from each other as well as different from the Santa Clara plant, but as neither was 

 in flower nor fruit and as they have not flowered in cultivation we are unable to identify 

 them, but in any case they are doubtless associated with the above. 



The plant much resembles in its habit some of the species of Echinocereus, but it has very 

 different flowers and fruit. Riimpler describes a species of Echinocereus (E. flavescens 

 Forster, Handb. Cact. ed. 2. 826. 1885) which from its name, description, and locality 

 suggests that it might be this species. Riimpler credits the name to Otto who described 

 a Cereus flavescens (Pfeiffer, Enum. Cact. 79. 1837), but without citing a locality for it. 

 A little later the Wilkes's Expedition collected near Lima a plant which we believe is the 

 same as ours and which Engelmann referred to Mammillaria flavescens, a quite different 

 species. The use of the same specific name is simply a coincidence for the indications are 

 that Engelmann did not know of Otto's name. 



The following account by Dr. Asa Gray appeared in Wilkes, U. S. Exploring Expedi- 

 tion (13: 660. 1854). 



"There are no specimens in the collection; but there is a good drawing, made from the living 

 plant by the late Mr. Agate; from which Dr. Engelmann has drawn up the characters given above 

 and the subjoined description and remarks. 'Stems several from the same very thick root, or pro- 

 liferous at the base, 2}4 to 3 inches high, an inch and a half or less in diameter, ovoid-cylindrical; the 

 setaceous straight prickles half an inch in length, brown. Flowers upright from the summit of the 

 stems, 14 lines long, 9 lines in diameter; the spreading sepals about 20 in number, linear-oblong, 

 obtuse, yellowish; petals about the same number, ovate-oblong, obtusish, yellow. Style half an inch 

 long; stigmas 9, radiate.' 



"M. flavescens is one of the very few species coming from tropical South America. The descrip- 

 tions which I find in different works agree tolerably well with our plant; though the stems are said 

 to be proliferous towards the summit, the spines are generally lighter-colored and the yellow flowers 

 appear in a ring around the top." 



Inquiry regarding Agate's drawing, referred to above, at the Gray Herbarium and at 

 the Missouri Botanical Garden, as well as an examination of Wilkes's manuscripts in the 

 U. S. National Museum at Washington, D. C, have been without results. 



Plate xxii, figure 2, shows the type plant collected by Dr. Rose in 1914 which fruited 

 at the New York Botanical Garden. 



27. SCLEROCACTUS gen. nov. 



Usually simple but sometimes clustered, spiny cacti; ribs rather prominent, more or less undu- 

 late or tubercled; spine-clusters well developed, some of the central ones hooked, the others straight; 

 flowers forming on the young areoles above and adjacent to the spine-cluster, subcampanulate, 

 purplish; ovary oblong, bearing thin scattered scales, each with a tuft of short wool in its axils; 

 fruit oblong to pyriform, nearly naked, dehiscing by a basal pore; seeds large, black, tuberculate; 

 hilum lateral, large; embryo strongly curved; endosperm abundant. 



Two species are known from the deserts of California, Utah, Colorado, Arizona, and 

 southern Nevada, of which Echinocactus polyancistrus Engelmann and Bigelow is the type. 

 The habit of the plants resembles somewhat that of Ferocactus, but the fruit is nearly naked 

 and the scales bear small tufts of wool in their axils. The seeds, too, are not smooth or 

 pitted as in Ferocactus but are tuberculate. 



The generic name is from anXtipos hard, cruel, obstinate, and kclktos cactus, referring 

 to the formidable hooked spines which hold on in a most aggravating manner. 



Key to Species. 



.Style puberulent; flower 3 to 4 em. long 1. 5. whipplei 



Style glabrous; flower 7 to 8 cm. long. 2. 5. polyancistrus 



