ONAGRACEAE (EVENING PRIMROSE FAMILY) 333 



81. ONAGRACEAE Dumort. EVENING PRIMROSE FAMILY 



Annual or perennial herbs, rarely shrubs, with alternate or opposite leaves, 

 no stipules or mere glands in their place, and axillary, spicate or racemose, 

 generally perfect, regular or sometimes irregular flowers. Calyx-tube adnate 

 to the ovary, often prolonged beyond it, the limb 2-6-lobed, usually 4-lobed. 

 Petals 2-9, mostly 4, convolute in the bud, rarely none. Stamens commonly 

 as many or twice as many as the petals and inserted with them on the summit 

 of the calyx-tube, or on the epigynous or perigynous disk. Ovary 1-6-celled, 

 usually 4-celled; styles united; stigma capitate, discoid or 4-lobed. Fruit 

 usually a capsule; ovules many in each cell. Seeds mostly small, sometimes 



with a coma. 



I 



Flowers 4-merous. 



Fruit a many-seeded capsule opening by valves. 

 Calyx-tube not prolonged beyond the ovary. 



Annuals; seeds not comose . . . . . . .1. Gayophytum. 



Perennials; seeds comose ....... 2. Chamaenerion. 



Calyx-tube prolonged beyond the ovary. 

 Seeds comose. 



Flowers showy, scarlet ....... 3. Zauschneria. 



Flowers small, not scarlet ....... 4. Epilobium. 



Seeds naked or sometimes tuberculate. 

 Stigma deeply cleft into 4 linear lobes. 

 Stamens equal in length. 



Flowers yellow; seeds in 2 rows 5. Onagra. 



Flowers white or pink; seeds in 1 row .... 6. Anogra. 



Stamens unequal, the alternate ones longer. 



Capsule not winged, but the rounded angles often more 



or less double crested ...... 7. Pachylophus. 



'Capsule winged or merely sharply angled. 



Plants stemless ....... 8. Lavauxia. 



Plants with diffuse wiry stems ..... 9. Gaurella. 



Stigma entire (discoid or capitate) or barely 4-toothed. 



Stigma discoid; stamens equal; calyx-tube funnelform 



above. 

 Calyx-tube longer than the ovary . . . .10. Galpinsia. 



Calyx-tube shorter than the ovary . . . .11. Meriolix. 



Stigma capitate. 



Calyx-tube cylindrical, longer than the ovary; capsule 



4-winged 12. Taraxia. 



Calyx-tube widened above, shorter than the ovary; 

 capsule not winged. 



Capsule linear, sessile 13. Sphaerostigma. 



Capsule more or less clavate, pediceled and obtuse . 14. Chylisma. 

 Fruit indehiscent, nut-like . . . . . . . .15. Gaura. 



Flowers 2-merous; fruit indehiscent and bristly with hooked hairs . 16. Circaea. 



1. GAYOPHYTUM Juss. 



Very slender branching annuals, with linear entire leaves and very small 

 axillary flowers. Calyx-lobes reflexed. Petals white or rose-colored. 



Subsimple or paniculately branched; capsule nearly sessile . . 1. G. caesium. 

 Usually freely branched above; capsules on elongated pedicels. 



Flowers large, 5-10 mm. broad . . . . . . . 2. G. diffusum. 



Flowers small, 2-4 mm. broad . . . . . . . 3. G. ramosissimum. 



1. Gayophytum caesium T. & G. Fl. 1: 514. 1840. Glabrous, or more or 

 less canescent with short appressed pubescence, the elongated branches 

 mostly simple: flowers 1 mm. long, axillary the whole length of the branches: 

 capsules linear, sessile or very shortly pediceled, 15-20 mm. long, usually 

 many-seeded: stamens in two sets; the anthers of the shorter set smaller. 

 G. racemosum. (G. Nuttollii T. & G. 1. c.) The western half of the United 

 States. 



2. Gayophytum diffusum T.&G. I.e. 513. Loosely dichotomously branched, 

 2-5 dm. high, somewhat canescent above or with spreading hairs through- 



