CROWFOOT FAMILY 295 



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. KEPENTES 



Leaves palmately divided. XI. ACRES. 



Beak long. XII. HISPIDI. 



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



or dissected leaves. XIII. MULTIFIDI. 



Achenes prickly; annuals. XIV. MURICATI. 



I. FLAMMULAE. 

 Plants rooting at the nodes. 



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



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

 Plants erect or ascending, not rooting at the nodes. 



Leaves appressed-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, 6-8 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 mm. long; plant low, seldom 2 dm. high; leaves very thin. 



6. R. alismellus. 

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



7. R. Populago. 



II. Nl VALES. 



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



Leaf-blades of the basal leaves reniform or flabelliform, 3-5-1 obed or 3-5-cleft. 



9. R. nivalis. 

 III. GLABERRIMI. 



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. JR. cardiophyllus. 



Petals wanting. 29. R. apetalus. 



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



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



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



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



Basal leaf-blades reniform or rounded-cordate. 14. JR. 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. eximius. 

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



half way 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 reniform, 



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. alpeophilus. 



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

 cleft deeper than half way down. 



