Genus 3. 



CACTUS FAMILY. 



Coryphantha similis (Engelm.) Britton & Rose {Mamil- 

 laria similis Engelm. J has stems tufted; flowers I'-z' long; 

 seeds about i" long, and ranges from Kansas and Colorado 

 to Texas. 



2. Coryphantha vivipara (Nutt.) Britton & 

 Rose. Purple Cactus. Fig. 2985. 



Cactus viviparus Nutt. Eraser's Cat. 1813. 



Mamillaria vivipara Haw. Syn. PI. Succ. Suppl. 72. 1819. 



Stems single or tufted, I'-s' high, i4'-2' in diameter. 

 Tubercles terete or nearly so, slightly grooved, bearing 

 3-8 slender reddish-brown spines 6"-io" long, sur- 

 rounded by 12-25 somewhat shorter, whitish or greenish 

 ones in a single row ; flowers purple, nearly 2' long ; 

 petals lanceolate, narrow ; sepals fringed ; berry ovoid, 

 6"-g" long, green ; seeds light brown, obovoid, curved, 

 pitted, about ¥' long. 



Plains and rocky soil, Minnesota to Manitoba, Alberta, 

 Kansas, and Colorado. 



4. OPUNTIA [Tourn.] Mill. Card. Diet. 

 Abr. Ed. 4. 1754. 



Succulent plants, with jointed branching stems, the joints flat, or cylindric, and small 

 mostly subulate deciduous spirally arranged leaves, the areolae axillary, often spine-bearing 

 and almost always with barbed bristles (glochides). Flowers usually lateral. Calyx-tube 

 not prolonged beyond the ovary, its lobes numerous, spreading. Petals numerous, slightly 

 united at the base. Stamens very numerous, arranged in several rows ; filaments distinct or 

 slightly united. Ovary cylindric, exserted; style cylindric, longer than the stamens; stigma 

 2-7-rayed. Berry pear-shaped, often spiny. [Named from a town in Greece.] 



About 200 species, natives of America. Besides the following, some 90 or more others occur 

 in the western and southwestern States. Type species; Cactus Opuntia L. 



Joints flattened, oval, oblong, obovate or orbicular ; stems prostrate or ascending. 

 Fruit fleshy, juicy, spineless or sparingly spiny. 

 Joints spineless, or with solitary stout spines. 



Joints spiny (no. 2 sometimes unarmed), the spines 1-15 at each areola. 

 Spines white, gray or yellowish. 



Joints 3'-5' long; longer spines l^'-i'A' long. 

 Joints 6'-8' long; longer spines I'-z'/i' long. 

 Spines reddish brown- to black; joints 6'-8' long. 

 Fruit dry, with spine-bearing areolae. 



Joints orbicular or broadly obovate, flat. 

 Joints little flattened, ovoid, or subglobose. 

 Joints cylindric, or nearly so ; stem erect. 



I. O. Opuntia, 



O. hiimifusa. 

 O. tortispina. 

 O. camanchica. 



5. O. polyacantha. 



6. O. fragilis. 



7. O. arhorescens. 



I. Opuntia Opuntia (L.) Coult. East- 

 ern Prickly Pear. Indian Fig. 

 Fig. 2986. 



Cactus Opuntia L. Sp. PI. 468. 1753. 



O. vulgaris Mill. Gard. Diet. Ed. 8, no. i. 1768. 



O. Opuntia Coult. Contr. Nat. Herb. 3: 432. 

 1896. 



Prostrate, or ascending, joints obovate, 

 oval or orbicular, 2'-5' long. Leaves subu- 

 late, appressed or somewhat spreading, 

 2"-4" long, usually early deciduous ; bristles 

 greenish or yellowish brown ; spines, when 

 present, solitary, grayish or variegated, 

 stout, not deflexed, 3"-ii' long, often want- 

 ing; flowers 5fellow, sometimes with a red- 

 dish center, 2-3' broad; petals 8-10; fruit 

 obovoid, fleshy, edible, I'-ii' long, red. 



In dry sandy soil, or on rocks, eastern Mas- 

 sachusetts to eastern Pennsylvania, Kentucky 

 and northern Florida. June-Aug. Prickly- 

 pear cactus. Devil's-tongue. Barberry. 



