OPUNTIACEAE 813 
Longer radial spines over 1 cm. long: stems erect. 3. E. Fendleri., 
Longer radial spines less than 1 em. long: stems procumbent. 4. E. Beriandieri. 
B. Joints less than 2 em. thick. 
Radial spines 4-6 : stems more or less angled : flowers over 7 cm. broad. 5. E. procumbens. 
Radial spines 9-12: stems terete: flowers less than 6 cm. broad. 6. E. Poselgeri. 
l. Echinocereus caespitósus Engelm. & Gray. Stems ovoid, globose or cylindric- 
ovoid, 2.5-5 or rarely nearly 15 cm. high, solitary or commonly 6-12 stems together, the 
ribs 12-13, straight ; tubercles confluent: areolae close together: spines numerous, white 
or rarely pink or brown; outer 20-30, straight or slightly recurved, pectinate, the lateral 
ones 4-8 mm. long, the upper and lower shorter ; central spines wanting or rarely 1 or 2 
but very short : flowers rose-purple, 5-7.5 cm. long and Al e as broad: hypanthium fur- 
nished with cushions bearing brown or black bristles: fruit ovoid, green, 18-20 mm. long: 
seeds black, 1.2-1.4 mm. long, tuberculate. 
On prairies, Kansas to Texas and adjacent Mexico.—A variety with reddish or chestnut-brown 
spines, is E. caespitosus castàneus Engelm. 
2. Echinocereus dübius ( Engelm.) Small. Stems ovoid-cylindric, 12-20 cm. high, 
pale green, rather flabby, usually tufted, the ribs 7-9, with tubercles: areolae remote : spines 
white, somewhat translucent ; lateral ones radiant, 12-30 mm. long, terete or slightly angled, 
upper ones reduced or obsolete ; central spines 1-4, straight or curved, 3.5-7.5 cm. long, 
angled : flowers pale purple, 6 cm. long and broad: fruit green or purplish, 2.5-3.5 
= w spiny : seeds globose-ovoid, 1.2-1.4 mm. long, tuberculate. [Cereus dubius 
ngelm. 
In river bottoms, southern Texas and adjacent Mexico. 
3. Echinocereus Féndleri (Engelm. ) Small. Stems ovoid to cylindric-ovoid, 7.5~20 
cm. high, 5-7.5 cm. thick, simple or branched at the base, the branches tufted, the ribs 9-12, 
sometimes oblique, tuberculate : areolae less than 1.5 cm. distant: spines short ; radials 
5-10, straight or sometimes curved, variable, lowest one 12-25 mm. long, shorter than the 
rest, angled, the next 2 about as long or longer, more or less blackish; succeeding ones shorter 
and weaker, 6-14 mm. long, occasionally accompanied by a spine at the top of the areolae 
surpassing all the rest in length; central spine solitary, nearly terete, 2.5-5 cm. long, 
reddish black, upcurved from a bulb Mes : flowers 6-8.5 cm. broad, deep violet 
purple: fruit 2.5 cm. long, purplish green, edible: seeds less than 1.5 mm. long. [Cereus 
Fendleri Engelm. ] 
In dry soil, Utah to Texas, Arizona and northern Mexico. 
4. Echinocereus Berlandièri ( Engelm. ) Small. Stems jointed, spreading, decumbent, 
much-branched, the joints nearly terete, 3.5-15 cm. long, 2-2.5 cm. thick, their ribs 5-6, 
with distinct tubercles: areolae quite close together: spines various; outer white, 6-8, 
radiant, 8-10 mm. long; central solitary, 10-25 mm. long, yellowish brown : flowers pur- 
ple, 5-10 em. long: fruit ovoid, nearly 2 cm. long, green, furnished with bristles: seeds 1 
mm. long, tuberculate. [Cereus Berlandieri Engelm. ] 
In river valleys, southern Texas. 
5. Echinocereus procimbens (Engelm.) Small. Stems jointed, diffusely branched, 
the joints nearly terete or 4-5-angled, 1.5-10 em. long, 12-16 mm. thick, contracted at the 
base, with 4 or 5 rows of distinct tubercles: spines rigid, rather slender; outer white, 
radiant, 5 or 4-6, 2-4 mm. long; central solitary, stouter than the outer, 4-6 mm. long, 
ascending or wanting: flowers delicate purple, fully 7.5 cm. long: fruit green, ovoid, 12-16 
mm. long: seeds lenticular, nearly 1 mm. thick. [Cereus procumbens Engelm.] 
In river valleys, southern Texas. 
6. Echinocereus Posélgeri (Coulter) Small. Stems weak, erect or reclining, sparingly 
branched, the joints slender, 30-60 cm. long, 8-16 mm. thick, the ribs 8, not very promi- 
nent, furnished with closely set areolae : spines bristle-like; outer white, 9-12, straight, 
barely 2 mm. lon ; central solitary, 4-6 mm. long, whitish to brown or black : flowers rose 
or purple, 5 em. Taig and broad : fruit about 2 cm. long, clothed with white and black 
bristles and wool : seeds less than 1 mm. long, tuberculate. [Cereus Poselgeri Coulter.] 
On rocky ridges, northern Texas and adjacent Mexico. 
3. CEREUS Mill. 
Plants with elongated cylindric prismatic or narrow angled or ribbed stems. Spine- 
bearing areolae more or less remote. Leaves obsolete. Flowers arising from areolae 
situated above fully developed spine-bearing areolae. Hypanthium prolonged beyond the 
ovary. Styles slender. Stigmas several. Fruit fleshy or dry. Seeds smooth or pitted. 
Embryo curved. 
