CHICKENWEED FAMILY 83 



Leaves short-petioled; flowers solitary in the axils. 



18. A. washingtoniana. 

 Leaves thick. 



Petals equalling or exceeding the sepals; branches simple, ascending. 

 Leaves ovate, bluish green, with strong midrib; petals longer than 



the obtusish sepals. 9. A. Edwardsii. 



Leaves oval, bright green; midrib not strong; petals equalling the 

 acute sepals. 19. A. Palmeri. 



Petals shorter than the sepals ; branches divaricately branched, spread- 

 ing. 20. A. polygonoides. 

 Plant more or less viscid, especially the upper portion; perennials with rootstocks. 

 Plant tall, 1-3 dm. high, erect; leaves hnear to lanceolate. 



Leaves linear or linear-lanceojate, 2—5 mm. wide. 21. A. Curtisii. 



Leaves lanceolate, 5-10 mm. wide. 22. A. Jamesiana. 



Plant low, diffusely cespitose; leaves ovate. 23. A. americana. 



2. CERASTIUM L. Mouse-ear Chickweed. 



Annuals; pod 2-3 times as long as the calyx. 



Pedicels in fruit 1-3 times as long as the calyx, straight or nearly so. 



1. C. brachypodum. 

 Pedicels in fruit 5 times as long as the calyx or longer; strongly curved above. 



2. C. nutans. 

 Perennials or rarely annuals; pods 1-2 times as long as the calyx. 



Leaves oblong, oval, or ovate, mostly obtuse, or barely acutish. 

 Petals 1 cm. long or more, fully twice as long as the sepals. 



Sepals, at least the outer ones, oval, obtuse, scarious-margined at the tip as 



well as on the sides. ^ 3. P. pulchellum. 



Sepals lanceolate, acute, scarious mostly on the margins only. 

 Leaves and stem distinctly, although not copiously villous. 



4. C. alpinum. 

 Leaves and stem flaely pilose. 5. C. Earlei. 



Petals less than 1 cm. long. 



Petals much exceeding the sepals. 



Leaves thick with a prominent midrib. 



Plant tall, 4-5 dm. high; leaves Unear-oblong. 12. C. Leibergii. 

 Plant low, depressed, less than 1 dm. high; leaves ovate-lanceolate. 



18. C. thermale. 

 Leaves thin; midrib not prominent. 



Sepals tinged with purple; stem depressed, 1-3-flowered. 



6. C. Beeringianum. 

 Sepals light green ; plant not depressed, 3-12-flowered. 



7. C. variabile. 

 Petals scarcely if at all exceeding the sepals; branches erect or ascending. 



Plant low and cespitose; leaves rather thick, all subsessile. 



8. C. Buffumae. 

 Plant taller and simple; leaves thin, the lower spatulate and with winged 



petioles. 9. C. vulgatum. 



Leaves, at least the lower ones, Unear or Unear-lanceolate, acute. 

 Leaves of the inflorescence short, broadly ovate, the rest linear. 



10. C. oreophilum. 

 Leaves all linear or lanceolate, or rarely linear-oblong. 



Inflorescence racemose-cymose, with almost erect branches, as well as the 



calyx copiously viscid. 11. C. elongaium. 



Inflorescence cymose, with ascending or spreading branches. 

 Lower leaves linear-oblong, 5-8 mm. wide; often obtvise. 



12. C. Leibergii. 

 Leaves Unear or linear-lanceolate, usually less than 5 mm. wide, all acute 



or acuminate. 

 Petals 12—14 mm. long, more than twice as long as the sepals. 



13. C. graminifolium. 

 Petals 10 mm. long or less, rarely twice as long as the sepals. 



Stem villous with reflexed hairs. 



Leaves thin and flaccid, those of the sterile shoots and fascicles 

 much narrower than those of the main stem. 



14. C. angustaium. 

 Leaves firm, with a thick midrib, all alike or those of the sterile 



shoots broader. 15. C. campestre. 



Stem flnely glandular-puberulent. 



Leaves thin and soft, all linear or narrowly linear-lanceolate; 



midrib not prominent. 16. C. scopulorum. 



Leaves thick and flrm; midrib prominent. 



Stem 1 dm. high or more; plant green; leaves not coriaceous, 



acute. 17. C. sirictum. 



Stem depressed, less than 1 dm. high; plant yellowish green; 

 leaves coriaceous, the lower often obtuse. 



18. C. thermale. 



3. AMMODENIA J. G. Gmel. l. A. oblongifolia. 



i. MOEHRINGIA L. 



Stem terete; leaves oval or elliptic-oblong; sepals obtuse or acutish. 1. M. lateriflora. 



