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. high. 



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. Arenaria tenella 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-lanceolate, 

 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, many-flowered, with 

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

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

 Nuttallii Pax. Dry mountains: Alta. Wyo. Utah Calif. B.C. Submont. 

 Mont. 



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

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

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

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



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

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

 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. verna (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 verna 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 solitary; 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 solitary; sepals 3 mm. long. 

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

 Alaska. Alp. Je An. 



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 solitary or rarely 2 or 3; 

 sepals elliptic-oblong, 4-5 mm. long, glandular-pubescent, strongly 3-nerved, 

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

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

 B.C. Mont. Alp. 



10. A. laricifolia (L.) Heller. Stems woody at the base, decumbent below, 

 very 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: Mont. 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 



