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10. HE. Texensis Hopf. Heads 20 to 30 cm, in diameter, flat, or very old ones some- 
times globose : ribs 13 to 27, acute and undulate: areole cordate: spines 1 to 5 cm. 
long, stout, ringed, more or less curved, reddish ; radials 6 to 7, the lowest wanting ; 
a solitary stouter flattened decurved central one: flowers rose-color, densely woolly, 
about5 cm, long: petals laciniate and aristate: berry scarlet and woolly.—From the 
Colorado southward, but apparently not westward beyond the Pecos. 
11. BE. bicolor Gal., var. Scnorrii Eng. Ovate, 10 to 15 em. high: ribs 8, obtuse 
and interrupted: radial spines 15 to 17, straight, the upper 2 to 4 longer (2.5 cm.), 
broader and flattened ; central ones 4, the uppermost oue broader and longer (3.5 
cm.); lower radial and central ones reddish variegated: flower 5 to 7.5 em. long, 
bright purple or rose-colored.—On the lower Rio Grande, 
12. H. intertextus Eng. Smaller, ovate-globose, 2.5 to 10cm. high: ribs 13, acute 
and interrupted: tubercles suleate: spines rigid, reddish with grayish-brown tip; 
radials 4 to 12mm, long, 16 to 25, closely appressed, the upper 5 to 9 more slender 
and subfasciculate, the lowest one short and stout ; central ones 4, the 3 upper ex- 
cecding the upper radials and intermixed with them, the single lower one short and 
perpendicular to the plant: flowers small, about 2.5 em. long, rose-color, closely 
clustered on the densely woolly apex: dry berry scarcely scaly, 8 mm. in diameter. — 
From the Limpia to El Paso. Var. Dasyacantiuus Eng., more common about El 
Paso, is ovate, with longer setaceous purplish-gray spines, radials spreading, and the 
lower central oue shorter than the rest. 
3. CEREUS Haworth. 
Plants of all sizes, low or climbing or erect, sometimes enormous, with 
spine-bearing areol on vertical ribs, usually larger flowers close above 
the bundles of full grown (older) spines, scales of ovary distinet with 
naked or woolly axils or almost obsolete, and the axils spiny, and a 
succulent often edible sometimes very large berry which is covered 
with spines or seales or almost naked. 
§ 1. Low and usually cespitose plants, mostly with numerous oval or cylindric heads, short 
flowers, green stigmas, and spiny fruit: seeds subglobose, covered with confluent tubercles. 
* Ribs numerous (10-21): areole very crowded, often elongated : spines numerous (12 to 30), 
, rigid, short (1-10 mm.), pectinate. 
+ Flowers greenish, 
1. C, viridiflorus Eng. Ovate or at length cylindrical, simple or sparingly 
branched, 2.5 to5 cm. high: ribs about 13: areoliew ovate-lanceolate : spines rarely 
more than 4 mm. long, closely radiate, 12 to 13, with 2 to 6 setaceous upper ones, re- 
maining laterals longer, lower often purplish-brown, remainder white; central often 
wanting, sometimes a single longer stouter variegated one: flowers lateral and to- 
wards the apex, about 2.5 cm. long: berries elliptical, sinall.—Between the Pecos 
and El Paso. The more common form is var. CYLINDRICUS Eng., which is larger and 
elongated, 7.5 to 15 cm, high or more, with more rigid and longer spines, 4 to 12mm, 
long. 
2. C. chloranthus Eng. Cylindrical, simple or sparingly branched, 7.5 to 25 em. 
high and 3.5 to 5 cm, in diameter: ribs 13 to 18: areolew ovate: spines loosely radiate, 
12 to 20, 4 to 10 mm. long, with 5 to 10 setaceous upper ones, mostly white; central 
ones 3 to 5, 18 to 30 mm. long, the upper 2 shorter and purplish, the lower 1 to 3 
longer, deflexed and white: flower lateral and on the lower part of the stem, very 
similar to the last: berries small—Common about El Paso. 
+ + Flowers yellow. 
3. C. dasyacanthus Eng. Subcylindrical, simple or branching from the base, 12.5 
to 30 cm. high, densely covered with numberless spines; ribs 16 to 21: areolw ovate: 
