CHICKWEED FAMILY 275 



Leaves usually 1 -nerved, obtuse, more or less triangular in cross-sec- 

 tion, fleshy. 8. A, Rossii. 

 Sepals obtuse. 



Petals equalling or somewhat exceeding the sepals: plant 1-5 cm. hi^?h. 



9. A, obtusiloba. 

 Petals twice as long as the sepals; plant about 1 dm. high. 10. A. laricifolia, 



1. A. tenella (Nutt.) Heller. Stem branched from the base, 5-20 cm. 

 high; leaves subulate, often arcuate, 5-10 mm. long; pedicels slender; sepals 

 strongly 3-ribbed, lanceolate, about 3 mm. long. Arcnaria tendla Nutt. Rocky- 

 places: Mont. — Wyo. — Ore. — B.C. Submont. My-Jl. 



2. A. dawsonensis (Britton) Rydb. Stem branched from the base, 1-3 

 dm. high; leaves filiform or linear-subulate, 1-2 cm. long; cyme open, with 

 slender pedicels; bracts lanceolate or subulate, green; sepals oblOng-liinceolate, 

 acute, 3-nerved, 4 mm. long; petals oblong. Hillsides: Yukon — Alta, — S.D. 

 Submont, — Subalp. Je-Jl. 



3. A. occidentalis Heller. Stems loosely matted, ascending or erect, 

 glandular throughout; leaves 6-10 mm. long; cymes open, man^'-flowcred, with 

 ascending or spreading branches; sepals lanceolate, 4-5 mm. long, long-attenu- 

 ate; petals shorter than the sepals. Areyiaria pungens Nutt., not Clem. A. 



Nuttallii Pax. Dry mountains: Alta.^Wyo.— Utah — Cahf. — B.C. Submont. 

 —Mont, 



4. A. tnacrantha Rydb. Stem diffusely branched and spreading, perfectly 

 glabrous; branches 1 dm. long or less; leaves subulate-fihform, obtuse, 5-10 mm, 

 long, 1-nerved; sepals lanceolate, 4-5 mm. long, very acute, scarious-margined. 

 Sandy soil in the moxmtains: Colo. Mont. Jl. 



6. A. propinqua (Richards.) Rydb. Stems branched from the base, 3-10 

 cm. high; leaves linear-subulate, flat, 3-nerved, ascending, 5-10 mm. long; c^-me 

 open, branches ascending; sepals lanceolate, 3 mm. long; petals about 4 mm. 

 long. Arenaria propinqua Richards. A. aequicaulis A. Nels. Sandy soil: 

 Hudson Bay— N.M. — Calif. — B.C. — Mack. Submont, — Alp, Jl-Au. 



6. A. vema (L.) Cockerell. Stems branched from the base, decumbent 

 below, 1 dm. high or less, glabrous; leaves linear-subulate, flat, rather soft; cyme 

 open, 1-3- (rarely 5-) flowered, with slender pedicels; sepals ovate, 3-3.5 mm. 

 long. Arenaria vema L. Sandy and rocky places: Greenl. — Que. — -Alta. — • 

 Alaska; n Eu. Subalp, — Alp, Jl-Au. 



7. A. quadrivalvis (R. Br.) Rydb. Stems tufted, 2-5 cm. high; leaves 

 lanceolate, flat, glabrous; flowers usually sohtary; sepals lanceolate, scarious- 

 margined, about 3 mm. long. Arenaria quadrivalvis R, Br, Arctic-alpine 

 situations: Arctic coast and Colo. Alp, Jl-Au. 



8. A. Rossii (Richards.) Rydb. Stems tufted, 1-5 cm. high, glabrous; leaves 

 linear, 5-8 mm. long, glabrous; flowers usually solitarj^; sepals 3 mm. long. 

 Arenaria Rossii R. Br. Alpine-arctic situations : Mack. — Colo. — Wash. — 

 Alaska. Alp, Je-Au. 



9. A. obtusiloba Rydb. Caudex much branched, woody; stems decumbent, 

 very leafy below^ glandular-pubescent, 1-5 cm. high; leaves subulate, rigid, 

 with a strong midrib, obtusish, 2-6 mm. long; flowers solitarj' or rarely 2 or 3; 

 sepals elliptic-oblong, 4—5 mm. long, glandular-pubescent, strongly 3-ner\'ed, 

 obtuse; petals spatulate, 6-7 mm. long. Arenaria obtusa Torr., not All. A. 

 sajanensis B. L. Robins, not Willd. Exposed mountains: Alta. — N.M. — Utah — 

 B.C. Mont.— Alp, 



10. A. laricifolia (L.) Heller. Stems w^oody at the base, decumbent below, 

 xery leafy; leaves linear-filiform, somewhat pungent, ciliolate or glabrous; 

 flowers 1-4 on each branch; sepals oblong, obtuse, 3-nerved, puberulent, 5-6 

 mm. long. Arenaria laricifolia L. Arctic-alpine situations: ^lont. — Alaska; 

 also in the Old World. Alp. * Jl. 



6. ARENARIA L. Sandwort. 



More or less diffusely branched annuals or perennials, sometimes woody at 

 the base. Leaves opposite, without stipules, often also fasciculate ones in their 



