BRITTON AND ROSE—STUDIES IN CACTACEAE. 941 
Opuntia chaffeyi Britt. & Rose, sp. nov. PuatTeE 72. 
Perennial, from a large, fleshy, deep-seated root often 35 cm. long and 4 cm. in diam- 
eter; stems annual, 5 to 15 cm. high, much branched near the base; joints elongated, 
3 to 5 cm. long, in cultivated specimens 25 cm. long, 6 to 7 mm. broad, slightly flat- 
tened, glabrous, pale bluish green or sometimes purplish; areoles circular, bearing the 
spines surrounded by white wool in the lower part and the yellow glochids surrounded 
by brown wool in the upper part; spines 1, rarely 2 or 3, needle-like, 2 to 3 cm. long, 
whitish or pale yellow; leaves minute, caducous; flowers not seen, but said to be rose 
color, small; fruit unknown. 
Type in the United States National Herbarium, no. 535976, collected on the 
Hacienda de Cedros, near Mazapil, Zacatecas, Mexico, May 20, 1910, by Dr. Elswood 
Chaffey. 
This is a most remarkable Opuntia, being the only one known which has annual 
stems, Dr. Chaffey after a careful investigation assures us that the species has this 
habit, although in exceptionally wet years the stem may be carried over until the 
next growing season. In our greenhouse it persists for several years. The young 
shoots suggest O. leptocaulis. We were at first inclined to consider it only a form of 
that species, but when good material was examined, it was seen to be very distinct. 
The joints, while narrow and elongated like those of the Cylindropuntias, are some- 
what flattened and the spines show no sign of a sheath. This indicates that the 
species is probably a Platyopuntia and related, but not closely, to Opuntia pumila. 
The species has been under observation in the greenhouse for two years, while 
Dr. Chaffey has repeatedly examined it in the field; but so far no flowers or fruit have 
been obtained. 
EXPLANATION OF PLATE 72,—Root and young branch, as received from the collector. Natural size. 
Wittia panamensis Britt. & Rose, sp. nov. PiateE 73. 
Pendent; joints much flattened; flowers solitary from the upper areoles, purple 
throughout, 2.5 to 3.5 cm. long before the lobes open, decidedly 5-angled, stiff; outer 
sepals 5, equal, obtuse, angled on the back, the inner ones 5, similar but thinner, not 
angled, a little longer, all erect; petals 10, thinner paler, and much smaller than the 
sepals, apiculate, forming an inner compact cylinder; tube proper 5 to 6 mm. long, 
the throat 10 mm. long; stamens in two clusters, one from the base of the throat on 
long filaments, one from the top of the throat on short filaments, all included; stigma 
lobes 4, white, remaining in a close cluster, the top exserted beyond the petals; 
ovary globular, purple, bearing a few scarious scales; fruit greenish white to pink, 
about 1 cm. long. 
Type in the United States National Herbarium, no. 691299, collected on mountains 
above Chepo, Panama, October 15, 1911, by H. Pittier (no. 4571), and flowered in 
Washington, April, 1912. Also collected by R. 8. Williams at Marraganti, Panama, 
April 3 to 9, 1908 (no. 698). 
The genus Wittia was described by Karl Schumann,! being based on a single species, 
W. amazonica. The present is a second species of this strange genus. As the illus- 
tration shows, the stem resembles that of species of Epiphyllum and of Rhipsalis, 
but the flowers are very different from those of either. 
EXPLANATION OF PLATE 73.—A flowering branch of the type specimen, in cultivation. Natural size. 
1 Monatsschr. Kakteenk. 18: 117. 1903. 
