ROSE—-MEXICAN AND CENTRAL AMERICAN PLANTS. 293 
Opuntia vilis Rose, sp. nov. PLATE XXVIL. Figure 36. 
Low creeping plants often forming mats several meters in diameter and only 10 to 
15 em. high; joints prostrate, then erect or ascending, the ultimate vertical joints 
clavate, 5 cm. long, the others 2 to 4 cm. long, very turgid, pale green with low 
tubercles; leaves terete, 2 to 3 mm. long, acute, red; young 
areoles with white wool; radial spines upward of 12, the 
number increasing with age by the addition of very small 
whitish ones; central spines of prostrate joints 4, reddish, 
white-tipped, 1 to 4 cm. long, terete, slightly scabrous, with 
a sheath 5 mm. long; of clavate joints, white, reddish on 
the upper surface at the base, and along the whole of the 
lower surface, flattened; flowers 4 cm. long; petals brilliant- 
purplish, 2 cm. long; filaments bright yellow with green 
bases; style white; stigmas yellow; fruit pale green, black- 
ening in drying, 2.5 to 2 cm. in diameter, 2.5 to 3 cm. long, 
tuberculate, especially about the margin of the scission; disc y,,, 35 —Kruit of Opuntia 
crenate and upper portions of the fruit correspondingly vilis. Natural size. 
fluted; fruit spiny, somewhat dry, with large white seeds. 
Collected by F. I. Lloyd on footslopes and plains, Zacatecas, Mexico, 1908 (no. 14). 
This species is nearest O. grahamii, from which it differs in its shorter, more terete 
joints, much shorter spines, and purple, not yellow, flowers. 
~ Called ‘‘perro’’ by the Mexicans. 
Type U.S. National Herbarium no. 535116. 
EXPLANATION OF PLATE XXVII.—From photograph taken by F. BE. Lloyd in northern Zacatecas, 
Echinocereus rigidissimus (Hngelm.) Rose. 
Echinocereus pectinatus rigidissimus Engelm. Proe. Am. Acad. 3: 279. 1856, 
Echinocereus pectinatus robustus Bauer, Gartenflora 1890: 513. pl. 1337. 1890. 
This Echinocactus is sometimes known in the trade as Cereus candicans, Cerens 
rigidissimus, Echinocereus robustior, Cereus robustior, ete. 
It is clearly distinct from both Echinocereus pectinatus and Hchinocereus cuespitosus 
and I have no hesitancy, therefore, in raising it to specific rank. 
Echinocereus centralis (Coult.) Rose. 
Cereus pectinatus centralis Coult. Contr. Nat. Herb. 3: 386. 1896. * 
Echinocereus pectinatus centralis Schum. Gesamtb. Kakteen 271. 1899. 
Professor Coulter when first describing this plant as a variety questioned whether 
it might not be a good species. It is quite distinct from true Mchinocereus pectinatus 
as well as Kchinocereus rigidissimus. — 
ONAGRACEAE. 
A NEW SPECIES OF GAURA AND ONE OF LAVAUXIA. 
Gaura grandiflora Rose, sp. nov. 
A rather coarse perennial, 40 to 60 cm. high; stems herbaceous, branching, the 
axis percurrent, with both long and short pubescence; branches many, ascending, 
more or less purplish; leaves lanceolate, 4 to 6 em. long, acute, somewhat toothed, 
pubescent on both surfaces; inflorescence somewhat pubescent, often early glabrate; 
ealyx buds glabrous; calyx tube slender, 3 to 3.5 cm. long; petals 2 to 2.5 em. long; 
anthers linear, attached near their middle; ovary and fruit glabrous, the latter 7 mm. 
long. 
Probably common in the mountains of Chihuahua and Durango. It has been con- 
fused with Gaura mutabilis of central Mexico, but is easily distinguished by its gla- 
brous calyx and fruit. 
