462 



CACTACEAE. 



Flowers yellow or reddish; central spine i. 

 Flowers purple ; central spines several. 



[Vol.. II. 



1. C. Missouriensts. 



2. C. viviparus. 



i. Cactus Missouriensis (Sweet.) Kuntze. Missouri or Nipple Cactus. 



(Fig. 2525.) 



Cactus mamillaris Nutt. Gen. i: 295. 1818. Not 



L- 1.753- 

 Mann //aria Missouriensis Sweet, Hort. Brit. 171. 



1827. 



M. Nullallii Engelm. Mem. Am. Acad. 4: 49. 1849. 

 Cactus Missouriensis Kuntze, Rev. Gen. PI. 259. 



1891. 



Stems mostly single, globose, I'-z' high. 

 Tubercles 6 // -8 // long, arranged in about 8 

 spiral rows, slightly grooved; spines gray, 10- 

 20 together, the stouter central one 5 // -6 // long, 

 or wanting; flowers yellow, or reddish, about i' 

 long and about the same breadth when ex- 

 panded; petals 2 // -3 // wide, acute, abruptly 

 mucronate; stigmas 2-5, very short, erect; berry 

 globose, scarlet, $"-4" in diameter, ripening 

 the following spring; seeds black, globose, 

 pitted, about W in diameter. 



Prairies and dry soil, South Dakota to Kansas 

 and Texas, west to Colorado. May. 



Cactus Missouriensis similis (Kngelm.) Coult. Contr. Nat. 



Hrrb. 3: in. 1894. 

 Mamillaria similis Engelm. Host. Journ. Nat Hist. 5: 246. 



1845. 



Stems tufted; flowers I'-a' long; seeds about i" long. 

 Kansas and Colorado to Texas. 



2. Cactus viviparus Nutt. Purple Cactus. 

 (Fig. 2526.) 



Cactus viviparus Nutt. Fraser's Cat. 1813. 

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



Stems single or tufted, i'-5' high, \]A'-i' in diam- 

 eter. Tubercles terete or nearly so, slightly grooved, 

 bearing 3-8 slender reddish-brown spines, 6 // -io" 

 long, surrounded 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 // ~9 // long, green; seeds light brown, 

 obovoid, curved, pitted, about %" long. 



Prairies, Manitoba to Alberta, Kansas, and Colorado. 



4. OPUNTIA Mill. Card. Diet. Ed. 7. 1759. 



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

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

 ing. Flowers usually lateral. Calyx-tube not prolonged beyond the ovary, its lobes nu- 

 merous, 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 where some species grew.] 



About 150 species, natives of America. Besides the following, some 50 others occur in the 

 western and southwestern States. 



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. i. O. Opuntia. 



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

 Spines white, gray or yellowish. 



Joints 3' -5 long: longer spines 1 A'-1 1 A' long. 2. O. humifusa. 



Joints 6' -8' long; longer spines I'-z'A' long. 3. O. tortispina. 



Spines reddish brown to black; joints 6' -8' long. 4. O. Camanchica. 



Fruit dry, with spine-bearing areolae. 



Joints orbicular or broadly obovate, flat. 5. O. polyacantha. 



Joints little flattened, ovoid, or subglobose. 6. O. fragilis. 



Joints cylindric, or nearly so; stem erect. 7. O. arborescens. 



