long; pollen fertile; capsule obovoid, 1-2 cm. long, on a pedicel (4-) 10-45 mm. 

 long; seeds in several indistinct rows in each locule, 1.2-1.5 mm. long. 



Gravel bars, wet alluvial flats and open places, rare and scattered, s. and w. Tex., 

 Mar. -May; to Col. and w. Venez.; cult, and naturalized elsewhere. 



2. Oenothera Kunthiana (Spach) Munz. 



Similar in general to O. tetraptera; plants subglabrous to strigulose; hypanthium 

 (0.5-) 1-2 cm. long; sepals 5-20 mm. long, with tips coherent at anthesis; petals 

 1-2 cm. long; pollen approximately 50% sterile. 



Gravel bars and wettish flat sandy often weedy places in the Trans-Pecos, 

 Edwards Plateau and s. Tex., Feb.-May; s. to C. R. 



3. Oenothera texensis Raven & Parnell. 



Well-branched strigulose or rarely hirsute perennial herb, flowering the first year, 

 to 5 dm. tall; leaves serrulate to sinuate-pinnatifid, elliptic to ovate, 2.5-4 cm. long, 

 8-18 mm. wide, the petiole 4-21 mm. long, flowers opening near sunrise; mature 

 buds erect; hypanthium 15-21 mm. long; sepals 15-18 mm. long, lacking free tips; 

 petals rose, 12-21 mm. long; pollen fertile; capsule obovoid, 8-14 mm. long, on a 

 pedicel 7-12 mm. long; seeds in several indistinct rows in each locule, 0.8-1 mm. 

 long. 



Gravel bars and along streams in canyons, Jeff Davis Co., in the Trans-Pecos, 

 Tex., May-Aug.; s. to Sin., Coah. and Tam. 



4. Oenothera rosea Ait. Rose sundrops. 



Well-branched strigulose or rarely hirsute perennial herb, flowering the first year, 

 to 4 dm. tall; leaves subentire or sinuate-pinnatifid, elliptic or rarely narrowly ovate, 

 2-5 cm. long, 1-2.5 cm. wide, the petiole 2-25 mm. long; flowers opening near 

 sunrise; mature buds erect; hypanthium 4-8 mm. long; sepals 7-12 mm. long, lack- 

 ing free tips; petals rose, 4-12 mm. long; pollen approximately 50% sterile; capsule 

 obovoid, 5-10 mm. long, on a pedicel 4-8 mm. long; seeds in several indistinct 

 rows in each locule, 0.7-0.9 mm. long. 



Along creeks and river bottoms in low weedy places, and in permanent marshy 

 cienagas, in the Tex. Trans-Pecos, Edwards Plateau and s. Tex., N.M. (Union Co.) 

 and Ariz. (Pinal, Cochise, Santa Cruz and Pima cos.), Apr.-Aug.; s. to Arg., a 

 pan-trop. weed. 



5. Oenothera fiava (A.Nels.) Garrett. 



Cespitose acaulescent rather sparsely strigillose to subglabrous perennial, with a 

 thick taproot; leaves in tufts or rosettes, oblanceolate, 5-20 cm. long, to about 15 

 mm. wide, deeply runcinate to runcinate-pinnatifid in the lower third, the terminal 

 lobe entire to undulate-dentate; flowers sessile among the leaves, vespertine; calyx 

 usually purplish, the free hypanthium slender, 2-12 cm. long; calyx lobes free or 

 slightly connate and turned to one side; petals yellow, aging to purplish, 1-2 cm. 

 long; anthers linear, 4-8 mm. long; stigma lobes linear, about 3 mm. long; capsule 

 woody, ovoid, 1-2 cm. long, conspicuously 4-winged; seeds numerous, dark-brown, 

 about 2 mm. long, minutely granular, cuneate-obovoid. 



In wet meadows, wettish flats, in swales or in wettish soil around vernal pools 

 in N. M. (Colfax, Rio Arriba, San Juan, San Miguel, Socorro and Taos cos.) and 

 Ariz. (Navajo. Coconino, Mohave, Yavapai and Gila cos.), Apr.-Sept.; Can. to 

 N.M., Ariz., Calif, and Mex. 



6. Oenothera canescens Torr. & Frem. Spotted primrose. 



Low bushy densely strigulose to canescent rhizomatous perennial with stems to 

 2 dm. long; leaves denticulate, lanceolate, 5-15 mm. long, 2-7 mm. wide, sub- 

 sessile; flowers opening near sunset; mature buds erect; hypanthium 5-15 mm. long; 



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