length, with 2 oblong lobules in the cleft, the serrulate trunk tapered to the base, 

 the claw not clearly delineated; stamens 5, to 1.5 mm. long, the oblong anthers 

 about 0.5 mm. long; ovary at anthesis subglobose, the short style bifid or trifid 

 more than half its length and slightly exceeding the anthers; capsule subglobose, 

 3-4 mm. long, mostly exceeding the sepals; seeds as many as 25, black, vermi- 

 culiform, facially gibbous, more or less tessellate, to 1.8 mm. long, about twice 

 as long as broad. 



On sand-gravel bars and in wet silty areas along streams and in dry plains 

 in Trans- Pecos Tex., N.M. (Don Ana and Otero cos.) and Ariz. (Cochise Co.), 

 often as a pioneer on bare areas, Jan.-Oct.; in w. U. S. and n. Mex. 



This plant is known to be toxic to sheep and cattle. 



3. Cerastium L. Mouse-ear. Chickweed 



Annual or perennial pubescent or hirsute herbs, sometimes viscid; flowers 

 white, few to many, borne in terminal dichotomous cymes, glomerules or singly 

 in leaf axils; sepals 5 or rarely 4; petals of the same number as the sepals or 

 rarely wanting, 2-lobed or -cleft; stamens 10 or rarely fewer; styles equal in 

 number to the sepals and opposite them, rarely fewer; capsule 1 -celled, cylin- 

 drical, often curved, membranaceous, opening at the summit by twice as many 

 teeth as there are styles, many-seeded; seeds rough. 



About 60 species that are widely distributed but mostly in temperature zones. 



1. Petals shorter than to about equal to the sepals (2) 



1. Petals slightly to decidedly longer than the sepals (3) 



2(1). Flowers arising singly in leaf axils along much of stem and branches 

 1. C. axillare. 



2. Flowers concentrated in cymes at apex of stem and branches 



2. C. vulgatum. 



3(1). Uppermost floral bracts with whitish scarious margins (4) 



3. All floral bracts green and herbaceous (5) 



4(3). Petals typically twice or more the length of sepals; basal branches and off- 

 shoots becoming dry and withered, not hirsute 3. C. arvense. 



4. Petals about as long as or very slightly exceeding the sepals; basal branches 



or off'shoots green, hirsute 2. C. vulgatum. 



5(3). Leaves usually 3 cm. long or less; fruiting pedicels about as long as to 

 shorter or rarely longer than the capsules, straight or at most only 

 gently curved 4. C. brachypodum. 



5. Leaves usually more than 3.5 cm. long; fruiting pedicels typically much longer 



than the capsules, rather abruptly curved just below the calyx 

 5. C nutans. 



1. Cerastium axillare Correll. Fig. 437. 



Plant apparently annual, to 3 dm. high, glutinously glandular-pubescent 

 throughout; stems few or many, suberect or ascending, sparsely branched; leaves 

 typically linear-oblanceolate but occasionally linear-elliptic to elliptic-lanceolate, 

 obtuse to subacute, to 3 cm. long and 8 mm. wide; flowers produced singly in 

 leaf axils along much of main stem and branches; pedicels slender, 1 cm. long 

 or less; sepals elliptic, 4-5 mm. long, obtuse to subacute, densely glandular- 

 pubescent (especially on lower half), with scarious margins, noticeably exceeding 

 the petals; petals elliptic-oblanceolate in outline, 3-4 mm. long, divided to near 

 the middle into linear-lanceolate subacute lobules; capsule about twice as long 

 as the calyx; seeds reddish-brown, tuberculate, about 0.5 mm. in diameter. 



On open-forested seepage slopes, rocky hills and in grasslands in the mts. of 

 Trans-Pecos Tex., Apr.-Sept.; also Chih. 



889 



