CROWFOOT FAMILY . 295 



Basal leaves elliptic to reniform. III. Glaberrimi. 



None of the leaves entire. 



Neither floating water plants nor creeping mud plants, if rooting at the 



nodes, the leaves not palmately lobed or dissected. 

 Achenes turgid, marginless. 



Petals much exceeding the sepals. 



Basal leaves not divided to the base. IV. Affines, 



Leaves all divided to the base; achenes glabrous. 



Leaves ternate, with simple linear divisions; plants very 



low, 0.5 dm, or less. V. Digitati. 



Leaves 2-3 times ternate; plants 5-20 cm. high. 



VI. Triternati. 

 Petals scarcely exceeding the sepals. 



Plants low. less than 1 dm. high. VII. Pygmaei, 



Plants taller, 3-6 dm. high. VIII. Abortivi. 



Achenes compressed, with a distinct margin. 



Beak of the achenes strongly hooked; heads of fruit globose. 



IX. Recurvati. 

 Beak of the achenes straight or nearly so; achenes in ours glabrous. 

 Beak short. 



Leaves, at least the basal ones, pinnately ternate, the ter- 



minal division at least petioled. X. Repentes. 



Leaves palmately divided. XI. Acres. 



Beak long. XII. HisPlDI. 



Immersed aquatics or creeping mud plants, with palmately lobed, divided, 

 or dissected leaves. XIII. Multifidi. 



Achenes prickly; annuals. XIV. Mubicati. 



I. FL.\MMX7LAE. 



Plants rooting at the nodes. 



Stem filiform, prostrate; petals about 3 mm, long, 1.' R. repians. 



Stem not filiform, at first ascending; petals about 5 mm. long. 2. H. unalaschensis. 

 Plants erect or ascending, not rooting at the nodes. 



Leaves ap pressed -pubescent on the lower side. 3. R. microlonchus. 



Leaves glabrous. 



Blades of the basal leaves acute at the base. 



Petals spatulate or oblong, usually 6-8, G-8 mm. long. 4. R. alismaefolius. 

 Petals obovate. usually only 5. 



Petals 7-10 mm. long; plants over 2 dm. high; leaves not very thin. 



5. R. Bolanderi, 



Petals 5-6 mjn. long; plant low, seldom 2 dm. high; leaves ver>- thin. 



6. R. alismellus. 



Blades of the basal leaves cordate or at least rounded at the base. 



7. R. Populago. 



II, Nivales. 



Leaf-blades spatulate or elliptic, 2-4-toothed at the apex. 8. R. Macauleyi. 



Leaf-blades of the basal leaves reniform or flabelliform, 3-5-lobed or 3~5-cleft. 



9. R, nivalis. 



III. Gl.\berrimi. 

 One species, 10. R, glaberrimus. 



IV. Affines. 



Achenes pubescent, with a short recurved beak; heads oblong to cylindric. 



Some of the basal leaf-blades merely crenate, the rest mostly 3-cleft at the apex, with 



a narrow middle lobe. 

 Sepals densely villous. 



Petals broadly obovate, about 1 cm. long. 11. R. cardiophyllus. 



Petals wanting. 29. R. apetalus. 



Sepals not densely villous; petals oblong-obovate, 3-6 mm. long. 



Petals 5-6 nun. long; heads of achenes oblong. 12. R. inamoenus. 



Petals 3-5 mm. long; heads of achenes cylindric. 13. R. micropetalus. 



Basal leaf-blades digitately or pedately cleft with acute lobes. 



Basal leaf-blades reniform or rounded-cordate. 14. R. affinis. 



Basal leaf-blades cuneate-flabelliform. 15. R. saxicola. 



Achenes glabrous; beak straight, usually slender. 



Plant glabrous, except the more or less villous sepals. 



Petals 7-12 mm. long; lobes of the basal leaves acutish. 



Basal leaf-blades cuneate-flabelliform; head of achenes somewhat oblong, 



5-10 mm. long. 

 Basal leaf-blades cleft half way down or less. 15. R. saxicola. 



Basal leaf-blades cleft more than half way down. 16. R. eiimius. 

 Basal leaf-blades reniform or at least truncate at the base, divided more than 

 halfway down: heads of achenes globular. 17. R. Suksdorfii, 



Petals 4-8 mm. long; lobes of the basal leaves obtuse or rounded. 



Heads of fruit decidedly oblong; basal leaf-blades orbicular, seldom remform, 



the earliest not cleft more than half way down. 

 Leaves thick; petals about 4 mm. long. 18. R, utahensis. 



Leaves thin; petals about 6 mm. long. 19. R, alpeophilns. 



Heads of achenes spherical or nearly so; basal leaf-blades decidedly remform, 



cleft deeper than half way down. 



