644 FLORA. 



7-10 cm. in diameter. Tubercles ovoid, somewhat 4-sided at base, 12-16 mm. 

 long, arranged in spirals; central spines yellowish below, nearly black above, 10- 

 14 mm. long, the exterior ones slightly shorter, whitish; flowers greenish pink, 

 1.5-2 cm. broad, borne to one side at the ends of the tubercles; petals oblong, cre- 

 nulate, cuspidate; berry dry, 6-7 mm. in diameter, bearing 2 or 3 scales near its 

 summit. Kans. (?), Colo, to Utah and Nev. April-May. 



3. CACTUS L. 



Stems globose or ovoid, tubercled. Tubercles conic or cylindric, woolly and 

 with clusters of spines at the apex. Leaves none. Flowers borne from areolae at 

 the bases of the tubercles. Calyx-tube prolonged beyond the ovary, which is often 

 hidden between the tubercles. Petals in several rows. Ovary smooth, ovoid; style 

 filiform. Berry emersed, crowned by the withering corolla. [Greek name of some 

 prickly plant.] About 300 described species, natives of warm and tropical Amer- 

 ica. Besides the following, 35 or more occur in the southwestern States. 



Flowers yellow or reddish: central spine i. i. C. Missotiriensis. 



Flowers purple; central spines several. 2. C, viviparus. 



1. Cactus Missouriensis (Sweet.) Kuntze. MISSOURI CACTUS. (I. F. f. 

 2525.) Stems globose, 2-5 cm. high. Tubercles 12-16 mm. long, arranged in 

 about 8 spiral rows, slightly grooved; spines gray, 10-20 together, the stouter 

 central one 10-12 mm. long, or wanting; flowers about 2.5 cm. broad; petals ab- 

 ruptly mucronate; berry globose, scarlet, 6-8 mm. in diameter, ripening the fol- 

 lowing spring; seeds black, globose, pitted, about I mm. in diameter. Plains 

 and dry soil, S. Dak. to Kans., Tex. and Colo. May. 



Cactus Missouriensis similis (Kngelm.) Coult. Stems tufted; flowers 2-5 cm. long; 

 seeds about 2 mm. long. Kans. and Colo, to Tex. 



2. Cactus viviparus Nutt. PURPLE CACTUS. (I. F. f. 2526.) Stems 2-13 

 cm. high, 3-5 cm. in diameter. Tubercles terete or nearly so, slightly grooved, 

 bearing 3-8 slender reddish-brown spines, 1-2 cm. long, surrounded by 12-25 

 somewhat shorter, whitish or greenish ones in a single row; flowers nearly 5 cm. 

 long; petals lanceolate, narrow; sepals fringed; berry ovoid, 1218 mm. long, 

 green; seeds light brown, obovoid, curved, pitted, about 1.5 mm. long. Prairies, 

 Manitoba to Alberta, Kans. and Colo. 



4. OPUNTIA Mill. 



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

 small mostly subulate deciduous leaves, the areolse axillary, often spine-bearing. 

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

 spreading. Petals numerous, slightly united at the base. Stamens very numer- 

 ous. 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 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 7-13 cm. long: longer spines 1-4 cm. long. 2. O. humifusa. 

 Joints 15-20 cm. long; longer spines 2. 5-6 cm. long. 3. O. tortispina. 

 Spines reddish brown to black; joints 15-20 cm. long. 4. O. Camanchica. 

 Fruit dry, with spine-bearing areolse. 



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. 



x. Opuntia Opuntia (L.) Coult. EASTERN PRICKLY PEAR. INDIAN FIG. 

 (I. F. f. 2527.) Prostrate or ascending; joints obovate, oblong, oval or orbicukr, 

 5-13 cm, long. Leaves subulate, 4-8 mm. long, usually early deciduous; bristles 



