MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 23 



Leaflets not tomentose beneath. 



Flowers 5-merous ; leaves usually all 5-foliolate. 



Bractlets lanceolate, about equalling the sepals. 



Stems long-assurgent ; first flower from .the axil of the second 



stem leaf or some subsequent leaf. 7. F. Canadensis. 



Plants low, less than 1 dm. high ; first fiower from the axis of the 



first stem leaf. 8. P. pumila. 



Bractlets ovate or elliptic, much exceeding the sepals. 9. P. reptam. 



Flowers 4-merous ; upper leaves 3-foliolate. 10. P. procumbens. 



Leaflets white-tomentose beneath ; flowers 5-merous. 11. P. longipes. 



§3. HETEROSEPALAE. 



Plant decumbent, in habit much resembhng certain species of the following group, 

 but evidently perennial ; the bractlets nearly always 3-cleft, which character has given 

 name to the species and the group. 

 A single Mexican and Central American species. 12. P. heterosepala. 



§4. SUPINAE. 



Plants annual, biennial or short-lived perennial, leafy ; the leaves of the many- 

 flowered cyme very little reduced, so that the flowers seem more or less axillary. Flowers 

 small, petals scarcely exceeding the sepals, often only half as long, yellow or whitish, 

 cuneate. Stamens often fewei- than 20, with short filaments and small didymous anthers. 

 Style short and thickened and glandular below, subterrainal ; stigma minute. 



To this group belong three or four European and Asiatic species and the following : 



Achenes with a corky gibbosity on the upper suture. 



Leaves all pinnate with 3-5 pairs of leaflets ; inflorescence cymose. 13. P. paradoxa. 



Lower leaves pinnate with 2-3 pairs, the upper ternate ; inflorescence 



falsely racemose. 14. P. Nieolletii. 



Achenes not gibbous. 



Leaves pinnate with 2 approximate pairs of leaflets, the upper (seldom all) 



ternate; stem strict ; inflorescence cymose. 15. P. rivalis. 



Leaves all ternate (the lower rarely 5-foliolate). 



Petals much shorter than the sepals ; achenes whitish. 



Stem diffusely branched, spreading ; leaflets cuneate, inflorescence cymose. 



Petals yellow ; stamens 10. 16. P. leuoocarpa. 



Petals white ; stamens 5 (Mexican). 17. P. Miehoaeana. 



Stem strict, leaflets bi^oadly obovate ; inflorescence falsely racemose. 18. P. biennis. 

 Petals about equalling the sepals ; stem strict. 19. P. Monspeliemis. 



Lower leaves digitately 5-foliolate, or ternate with the lateral leaflets 2-cleft 



to near the base. 20. P. pentandra. 



