OXAGRACEAE. 173 



the ovary, 4-parted; petals 4, white or rose-colored, very small, 

 obovate or oval, with a very short claw; stamens 8; anthers 

 broad or rounded, attached by the middle, those opposite the 

 petals on shorter filaments and usually sterile; ovary 2-celled; 

 fruit a dehiscent capsule, seeds few-many, naked, in one row. 



Capsules nearly sessile; stems simple or branched from the 



base. G. pumilum. 



Capsules on slender pedicels; stems branched above. 



Seeds glabrous. G. ramosissimum. 



Seeds canescent. G. lasiospermum. 



Gayophytum pumilum Wats. Erect, simple or branched at base, 5-15 

 cm. high, glabrous or minutely puberulent; leaves numerous, lanceolate, 

 acute, attenuate to the sessile base, 1-2 cm. long; flowers minute; capsules 

 stout, sessile, 10-22 mm. long, usually appressed to the stem; seeds smooth. 

 Moist bare places in the mountains. 



Gayophytum ramosissimum T. & G. Erect, with usually many slender 

 branches, glabrous below, puberulent above, 15^10 cm. high; leaves linear 

 or linear-lanceolate, 1-4 cm. long, acute, attenuate at the sessile base; flowers 

 pink, small, 24 mm. broad, pedicelled; capsules oblong or somewhat club- 

 shaped, often torulose, 6-12 mm. long, spreading, on rlender pedicels, some- 

 times deflexed; seeds not hairy. Dry soil, especially in open woods. 



Gayophytum lasiospermum Greene. Very similar to G. ramosissimum and 

 to be distinguished certainly only by the seeds, which are canescent with an 

 appressed silky- pubescence. In sandy or gravelly soil. 



246. PACHYLOPHUS. 



Perennial acaulescent or nearly acaulescent herbs; leaves basal, 

 pinnatifid or pinnately-toothed, petioled; flowers basal, more or 

 less tufted ; calyx-tube linear-f unnelform ; segments narrow, one- 

 third to one-half the length of the tube; petals white or pink; 

 stamens 8, equal; anthers attached near the middle, versatile; 

 capsule 4-celled, pyramidal, its angles retuse or obtuse, trans- 

 versely wrinkled ; seeds sessile, in one or two rows. 



Pachylophus marginatus (Nutt.) Rydb. Stemless or nearly so, with a 

 thick tap-root; leaves all radical, lanceolate or oblanceolate, obtuse or acute, 

 sinuately irregular-dentate or pinnatifid, 5-10 cm. long, narrowed into a 

 petiole about as long, villous or nearly glabrous except the villous margin; 

 flowers barely exceeding the leaves, rose-colored, 4-6 cm. broad; calyx-tube 

 narrow, 5-10 cm. long, much longer than the ovary, the lobes lanceolate, 

 somewhat reflexed; capsule oblong-ovate, sessile or nearly so, 3-4 cm. long. 

 Bluffs of Snake River. 



247. OENOTHERA. EVENING PRIMROSE. 



Annual, biennial or perennial herbs with prostrate or erect 

 stems; leaves alternate, entire, toothed or pinnatifid; buds erect 

 or drooping; flowers white, pink or yellow, blooming by night or 

 by day; flowers axillary or in terminal spikes; calyx-tube 

 elongated, terete, filiform or enlarged upward; segments narrow, 



