TH Y ME LEA CEA E. 645 



greenish or yellowish brown; spines, when present, solitary, stout, not deflcxed, 

 6-35 mm. long; flowers yellow, sometimes with a reddish center, 5-8 cm. broad; 

 fruit obovoid. edible, 2.5-4 cm. long, red. In dry sandy soil, or on rocks, E. 

 Mass. to Penn. and Fla. June-Aug. [0. vulgaris Mill.] 



2. Opuntia humifusa Raf. Western Prickly Pear. (I. F. f. 2528.) 

 Prostrate, similar to the preceding; joints obovate, suborbicular, or oval, usually 

 deep green. 7-13 cm. long; leaves subulate, spreading, 6-10 mm. long; bristles 

 reddish brown; spines few, mostly near the margins, 1-4 together, deflexed, or the 

 longer one spreading and 1-2.5 cm. long; flowers 6-10 cm. broad; fruit club- 

 shaped, not spiny, edible, 3-5 cm. long. In dry sandy or rocky soil, S. Dak. to 

 Minn., Ky., Mo., Kans. and Tex. Summer. 



3. Opuntia tortispina Engelm. Twisted-spined Cactus. (I. F. f. 2529.) 

 Stems prostrate, the orbicular-obovate flattened joints 15-20 cm. long. Spines 

 3-5. white, angled, the longer ones 3-6 cm. long, with 2-4 more slender and shorter 

 ones; flowers sulphur-yellow, 6-8 cm. broad; fruit ovoid, fleshy, unarmed, about 

 5 cm. long; seeds orbicular, slightly notched at the hilum. Plains, Neb. to Tex. 



4. Opuntia Camanchica "Engelm. Comanche Cactus. (I. F. f. 2530.) 

 Prostrate, with obovate-orbicular flattened joints 15-20 cm. long. Spines 1-3, 

 flattened, reddish brown to blackish, 3-8 cm. long, or with 3-6 additional shorter 

 ones, the upper one suberect, the others deflexed or spreading ; fruit oval, deep red, 

 3-5 cm. long; seeds angular, margined, deeply notched at the hilum. W. Kans. (?), 

 Colo, to Tex. and Ariz. 



5. Opuntia polyacantha Haw. Many-spined Opuntia. (I. F. f. 2531.) 

 Prostrate; joints obovate to orbicular, tubercled, 5— 15 cm. long, about 1.2 cm. 

 thick, the tubercles 4 mm. high, densely spiny and with cushions of fine bristles; 

 spines 5-12, slender, 1-5 cm. long, whitish; leaves minute; flowers light yellow, 

 5-8 cm. broad; fruit dry, very prickly, 2-3 cm. long. Prairies and dry soil, S. 

 Dak. to Br. Col., Neb., Mo. and N. Mex. May-June. 



6. Opuntia fragilis (Nutt.) Haw. Brittle Opuntia. (I. F. f. 2532.) De- 

 cumbent or prostrate; joints ovate, 2-5 cm. long, nearly terete. Leaves small, red- 

 dish; cushions composed of few bristles; central spines 1-4, 1-4 cm. long, gray, 

 darker at the apex, surrounded by 4-6 smaller ones; flowers yellow, smaller than 

 those of the preceding; fruit nearly 2.5 cm. long, becoming dry at maturity, pro- 

 vided with cushions of bristles usually bearing a few short spines. Prairies and dry 

 soil. Wis. and Minn, to S. Dak., Utah, Kans. and N. Mex. 



7. Opuntia arborescens Engelm. Northern Tree-like Cactus. (I. F. 

 f- 2 533-) Erect, tree-like. 1-8 m. high, 1-2 dm. in diameter at the base, verticil- 

 lately branched. Joints verticillate, mostly in 3's and 4's, cylindric, 5-15 cm. long, 

 the tubercles 1.5-2 cm. long; leaves terete, 1-2 cm. long; spines 8-30, terete, in 

 yellowish sheaths, diverging, the interior ones often 2.5 cm. long or more; flowers 

 purple, 6-8 cm. broad ; fruit subglobose, tuberculate, dry, or nearly so, yellow, 

 unarmed, about 2.5 cm. in diameter. W. Kans., Colo, to Tex., N. Mex. and Mex. 



Order 25. THYMELEALES. 



Mostly shrubs or trees, with simple leaves and incomplete flowers. 

 Calyx inferior, 4-5-lobed or entire. Corolla mostly wanting. Stamens 

 twice as many as the calyx-lobes, or fewer. Ovary 1 -celled. Ovule 1, 

 anatropous. 



Leaves green ; seed pendulous. Fam. 1. Thymeleaceae. 



Leaves silvery-scurfy; seed erect. Fam. 2. Elaeagnaceae. 



Family 1. THYMELEACEAE Reichenb. 



Mezereon Family. 



Shrubs or trees (rarely herbaceous), with tough inner bark, and entire 

 estipulate leaves. Flowers fascicled, capitate, racemose, or rarely soli- 

 tary, regular, mostly perfect. Calyx-tube cylindric or urn-shaped. Petals 



