3(1). Capsules dehiscent by 3 valves or teeth 3. A. patula. 



3. Capsules dehiscent by 6 (rarely 4 or 5) valves or teeth (4) 



4(3). Sepals obscurely 3- to 5-nerved; leaves ovate, 3-5 (-7) mm. long; annual.... 

 4. A. serpyllifolia. 



4. Sepals prominently 1 -nerved; leaves lanceolate to narrowly elliptic or linear- 



oblanceolate, typically more than 10 mm. long; perennial 



5. A. lanuginosa. 



1. Arenaria obtusiloba (Rydb.) Fern. 



Cespitose perennial from a woody caudex. forming mats to about 4 dm. across, 

 the trailing stems covered with marcescent leaves; basal leaves numerous, linear, 

 imbricate, 5-10 mm. long, mostly less than 0.5 mm. wide, mucronulate, 1 -nerved, 

 ciliolate or glandular-pubescent to glabrous; flowering stems erect, to about 6 cm. 

 tall, supporting 1 to rarely 3 erect flowers, with 1 or 2 pairs of reduced bracts, 

 granular-puberulent to pubescent and more or less glandular above; sepals oblong, 

 4—5 mm. long, 3-nerved, obtuse, the usually purplish tip membranous and typically 

 somewhat erose and slightly cucullate, mostly glandular-pubescent; petals nar- 

 rowly oblong-oblanceolate. to about twice as long as the sepals; styles 3 or some- 

 times 4; capsule ovoid-cylindric, 3-valved, to about twice as long as the sepals; 

 seeds essentially smooth, reddish-brown, 0.7-1 mm. long. 



In wet seeping subalpine and alpine meadows, on gravel bars and talus slopes 

 in N. M. (Taos Co.) and Ariz. (Coconino Co.), July-Sept.; Greenl. to Alas., s. 

 in mts. to N. M. and Ariz. 



2. Arenaria rubella (Wahlenb.) J. E. Sm. 



Cespitose perennial, typically with a small taproot and a branched crown, 

 forming cushions to about 1 dm. across, finely glandular-puberulent or -pubescent 

 throughout or the leaves and calyx glabrous; stems numerous, short, prostrate, 

 with marcescent leaves; leaves mostly basal and somewhat imbricate, linear to 

 linear-subulate, usually to about 1 cm. long, obtuse to slightly acicular, 3-nerved, 

 those of sterile shoots with fascicled secondary leaves in their axils; flowering 

 stems usually to about 8 cm. tall, very slender, simple or dichotomously branched, 

 with 1 to rarely as many as 7 flowers in an open leafy-bracteate cyme; the leaves 

 shorter than the internodes; sepals lanceolate, 2.5-4 mm. long, acute to acuminate, 

 scarious-margined, 3-nerved; petals slightly shorter to slightly longer than sepals; 

 stamens borne on the edge of a perigynous disk surrounding the ovary; styles 

 3; capsule narrowly ovoid, slightly exceeding the calyx, 3-valved; seeds light- 

 brown, finely tesselate-tuberculate, about 0.5 mm. long. 



In wet meadows and slopes in subalpine and alpine regions and on gravelly 

 stream banks in N. M. (reported from but not seen) and Ariz. (Coconino Co.), 

 June-Aug.; Greenl. to Alas., s. in mts. to N. M., Ariz, and Calif.; Euras. 



3. Arenaria patula Michx. Fig. 438. 



Diffusely branched annual with capillary stems to 3 dm. high; leaves slightly 

 fleshy, linear-filiform to linear-lanceolate, to 4 cm. long and 3 mm. wide; pedicels 

 divergent, to 45 mm. long, often glandular; sepals elliptic to lance-attenuate, 

 acute at apex, often somewhat glandular, to 6 mm. long, strongly 3- to 5-ribbed; 

 petals obcordate, to 3 times the length of the sepals; capsule about equaling or 

 exceeding the calyx, its blunt valves entire; seeds 0.5-0.6 mm. long. 



In sandy, clayey or gravelly soil in prairies, wet meadows, fields and on rock 

 outcrops, in Okla. (Waterfall) and mostly in e. Tex., Mar.-May; from Ala., 

 Tex. and Ark., n. to e. Kan., O. and Minn. 



Var. patula may be distinguished from var. robusta not only by its smaller 

 more compact size, seldom attaining more than 15 cm. in height, but by its 



895 



