400 
wanting: flowers 2 em. high, 5 em. broad, pinkish-white (in dried spee- 
imens).—Type unknown. 
From San Luis Potosi southward throughout Mexico. 
Specimens examined: SAN Luis Povost (Poselger of 1850; Parry 
& Palmer 274; Parry of 1878; Pringle 3743): also cultivated in lort. 
Pfersdorff in 1869, 
Pringle’s specimens are in flower, and from them the above description of the flower 
is taken. The radials are also shorter than in the criginal description as given 
above, varying from 3 to 5mm, in length, with the stout central about 3 em. long. 
The radials are always 5 in the specimens examined, their broad bases in contact, 
forming a regular hexagon, with the spine that would form the uppermost angle 
wanting and replaced by the floriferous areola, The broad base of the very stout 
solitary central is in contact With the bases of all the radials, completely fllling up 
the space. In one case observed the central was but 8 mm. long and the radials 
very minute. 
48. Cereus greggii Engelm. Wisliz. Rep. 18 (1848), 
Cereus pottsit Salin, Cact. Hort. Dyek. 208 (1850). 
Cereus greggti transmontanus Engelm, Syn. Cact. 287 (1856). 
Stem slender, erect, 6 to 12 em. high, 18 to 25 mm. in diameter, from 
a very large tuberous root (often 15 to 25 em. long and 10 to 15 em. in 
diameter); branches erect, reddish or dark-green: ribs 3 to 6 (usually 4 
or 5), acute, with crowded areolie: spines abruptly subulate from a 
bulbous base, very short (1 to 2 mm.) and sharp, blackish at length 
ashy; radials 6 to 9, subrecurved, the lowest slenderer and longer; cen- 
trals 1 or 2 (when 2 they are in the same vertical plane and divergent 
upward and downward): flowers whitish or ochroleucous, 15 to 20 em. 
long, 5 to6 em, broad: fruit ovate, attenuate at base and acuminate, 
2.5 to 3.5 cm, Jong, 2.5 em. in diameter, bright-scarlet, fleshy and edible: 
seeds obliquely obovate, rugose, black, 2.5 to 3mm. long. (IIL Cact. 
Mex. Bound. t. 65-65)—Ty pe, Gregg 222 and 599 in Herb. Mo. Bot. Gard, 
From southwestern Texas (Pecos and westward), westward through 
southern New Mexico into Arizona, and southward into Chihuahua 
and Sonora. In gravelly or hard clayey soil. 
Specimens examined: TEXAS (Wright 347, 513, of 1852; Bigelow of 
1852; Parry of 1853; no date or collector, foothills near Alpine): NEW 
MEXICO (Hrans of 1891): ARIZONA (Bendre of 1872; Engelmann of 
1880; Pringle 10; Toumey of 1892, Tucson; VTrelease of 1892): Cummua- 
HUA (Gregg 222, 599), 
This very characteristic species seems to be scattered and rare throughout its 
range. A single slender stem usually arises from the enormous root, but sometimes 
there may be many stems. 
49. Cereus pitajaya (Jacy.) DC. Prodr. iii, 466 (1828). 
Cactus pitajaya Jaeq. Knum, Pl, Carib. 23 (1763). 
Cereus undulosus DC. Rey, Cact. 46 (1829). 
Cereus letevirens Salm, Cact. Hort. Dyck. 336 (1834). 
Cereus variabilis Pfeiff, Enum. 105 (1837), not Engelm. (1850). 
Stem simple or branching at base, suberect, green or glaucescent, 3.5 
to 7.5 cm. in diameter: ribs 3 to 5, obtuse and repand, with areole 8 to 16 
