376 
47. Echinocactus erectocentrus, sp. nov. 
Broadly ovate and simple, with very flat base, 8 em. high: ribs 21, 
oblique, tuberculate-interrupted: spines terete, rigid, interwoven; 
radials 14, pectinate-appressed below, spreading above, bulbous at 
base, 10 to 12 mm. long, the 4 or 5 lower ones shorter, with white base 
and pink tips; the solitary central from the upper part of the areola, 
longer (20 mm.), erect and slightly curved, darker: flowers yellow (2): 
fruit unknown.—Type in Nat. Herb. and Herb. Coulter. 
Near Benson, Arizona, and also near Saltillo, Coahuila. 
Specimens examined: ARIZONA (Hvans of 1891): COAMUILA ( Weber 
of 1869). 
The plant is characterized by its very flat base, on which the spines are persistent 
even to the ovigin of the root, and by uniformly erect centrals. It is nearly related 
to £, horripilus Lem., to which the Webber plant has been referred, but judging by 
descriptions of that species, no such reference can be made on account of its much 
snuiller spines, more numerous radials, strictly erect centrals, and always simple 
habit. It seems so unlikely that this species would be found at such widely-separated 
stations as Benson, Arizona, and Saltillo, Coahuila, that there must be a suspicion of 
shifted labels on the part of one of these collectors. Mr. Evans’s only Mexican collec- 
tions are from Chihuahua, just across the Rio Grande from E] Paso, and it is barely 
possible that this plant should bear a Chihuahua label, but this is only suggested by 
the location of the Webber station, 
=== Tubercles distinet (as in Cactus): flowers yellowish or whitish (in No. 50 some 
times shading to purple). 
48. Echinocactus sileri Engelm. MSS. 
Globose: ribs 13, prominent, densely crowded, with short rhomie- 
angled tubercles: radial spines 11 to 13, white; central 3, black with 
pale base, 18 mm. long, the upper one slightly longer: flowers scarcely 
2.9 cm. long, straw-colored: fruit unknown.—Type, Siler of 1883 in 
Herb. Mo. Bot. Gard. 
Cottonwood Springs and Pipe Springs, southern Utah. 
Specimens examined: UTAn (A. LZ. Siler of 1883). 
49. Echinocactus papyracanthus Engelm. Trans. St. Louis Acad. ii, 202 (1863), 
Mamillaria papyracantha Engelm. Pl. Fendl, 49 (1849). 
Ovate, about 5 em. high and 3.5 em. in diameter, proliferous: ribs 8, 
oblique, completely broken up into tubercles, of which the lower ones 
are proliferous: all the spines flat, chartaceous, flexible, and silky-white; 
radials 8, short (3 to 4 mm.), all directed laterally or downwards; cen- 
trais 3 or 4, much longer, the 2 or 3 upper ones curved upwards, 12 to 
18mm. long, the single lower one longer (20 to 28 min.) and broader (2 to 
2.omim.), turned downwards: flowers 2.4 to 2.6em. long and slightly 
broader, pearly white: fruit unknown.—Type, Fendler 279 of 1847 in 
Herb. Mo. Bot. Gard. 
“In a valley between the lower hills,” near Santa Fe, New Mexico, 
‘in loose red sandy though fertile soil.” 
Specimens examined: New MExico (Fendler 279 of 1847; Bandelier 
of 1882). 
