narrower leaves (1.5 mm. wide or less), prominently 5-ribbed sepals, capsules 

 mostly shorter than the calyx, and its corolla scarcely exceeding the calyx. 



Var. robusfa (Steyerm.) Maguire is a larger more open plant with wide leaves, 

 3-ribbed sepals, capsules commonly exceeding the calyx, and corolla prominently 

 exceeding the calyx. 



4. Arenaria serpyllifolia L. Thyme-leaved sandwort. Fig. 438. 



Annual, the stems simple to intricately forking, to 2 dm. high; branches 

 cinereous-puberulent; leaves ovate, sessile, acute to acuminate, ciliate, scabrous, 

 to 7 mm. long; inflorescence a leafy nearly regular panicle of dichotomous 

 cymes; pedicels straight, to 1 cm. long; fruiting calyx 3-4 mm. long, 2-3 mm. 

 broad at base, composed of lanceolate to ovate-lanceolate acuminate 3- to 5- 

 nerved scabrous sepals; petals oblong, shorter than the sepals; capsule ovoid 

 to flask-shaped, its 2-cleft olive valves hard and resistent; seeds globose-reniform. 

 opaque, strongly rugose, about 0.6 mm. long. 



Along river bars, in wet meadows and seepage areas, a weed of fields, lawns 

 and roadsides, in Okla. (Waterfall), e. and cen. Tex., Mar.-July; a Eur. adv. 

 that has become naturalized from Fla. to Calif., n. to Que., Tenn. and Mo. 



5. Arenaria lanuginosa (Michx.) Rohrb. 



Perennial with more or less creeping subterranean stems; flowering stems lax, 

 weak and reclining or sometimes trailing, to about 6 dm. long, with lines of 

 minute pubescence; leaves thin, lanceolate to narrowly elliptic or linear-oblanceo- 

 late, acute or pungent, narrowed to a somewhat ciliate base, to 3 cm. long and 

 8 mm. wide, more or less punctate; flowers axillary, subtended by leafy bracts; 

 pedicels slender, puberulent, to 4 cm. long; sepals lanceolate, acute to acuminate, 

 3-4 mm. long, somewhat dorsally keeled along the solitary midnerve; petals white, 

 about half as long as sepals, sometimes wanting; capsules about 5 mm. long; 

 seeds smooth, shining, black, flattened, about 1 mm. in diameter. A. alsinoides 

 Willd., A. confusa Rydb., A. saxosa Gray. 



In loam of damp woods, wet meadows, shaded ditches and other such places 

 throughout our region, uncommon, June-Oct.; from Fla. to Calif, and Mex., n. 

 to Va.; also W. I. and S. A. 



Var. cinerascens (Robins.) Shinners is a somewhat more rigid plant than is 

 var. lanuginosa, grayish throughout with a fine pubescence, and leaves pungent. 

 Also, their flowers have petals that are about half as long as the sepals. 



6. Sagina L. Pearlwort 



Small often inconspicuous annual or perennial herbs; leaves subulate-filiform 

 to linear, opposite, scarious-connate at base; flowers terminal, usually solitary 

 and long-pediceled; sepals free, 4 or 5 (6) or none; petals usually shorter than 

 sepals, entire, white; stamens 3 to 10; styles 4 or 5 (6); capsule ovoid or 

 spheroid; seeds numerous, smooth. 



About 25 species that are native to the Northern Hemisphere. 



1. Plants forming dense mats, perennial; distribution in mountains of New 

 Mexico and Arizona 1. S. saginoides. 



1. Plants not forming mats, annual; distribution in eastern half of Oklahoma 

 and Texas 2. S. decumbens. 



1. Sagina saginoides (L.) Karst. Fig. 436. 



Perennial with leafy rosettes clustered at base; stems rarely to 5 cm .long; 

 branches decumbent or ascending, forming mats to 1.5 dm. across; leaves filiform- 

 subulate, to about 2 cm. long, somewhat bristle-tipped; flowers terminal, 5- or 

 rarely 6-merous; pedicels 1-3 cm. long, erect, hooked at summit after anthesis, 

 becoming straight, glabrous; sepals 1-3 mm. long, oval to oblong, glabrous, 



897 



