MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 



19 



my specific lines are nearly the same as those of Professor Greene.^ In addition I have 

 described a few new species and have made a few necessary changes. 



KEY TO THE GENERA. 



Style terminal or nearly so ; ovules pendulous and anatropous. 



Hypanthium saucer-shaped to deeply campanulate ; petals oblanceolate to 

 obcordate. 

 Anthers ob long, opening by longitudinal slits ; pistils several to many, 

 very rarely one. 

 Stamens inserted very near the base of the receptacle on a more or 



less evident annular thickening. 

 Stamens separated from the receptacle by a wide open space ; no in- 

 dication of an annluar thickening. 

 Anthers obcordate, opening by subterminal pores ; pistils 1. 

 Hypanthium wheel-shaped ; petals narrowly linear ; pistils 2. 

 (Style terminal, ovules basal, erect. 

 Style lateral ; ovules ascending and amphitropous. 

 Aclienes glabrous ; herbs. 



Achenes numerous ; stamens 20. 



Receptacle not enlarged in fruit ; leaves interruptedly pinnate; flowers 



yellow. 

 Receptacle in fruit somewhat enlarged and spongy ; leaves pinnate ; 



petals red. 

 Receptacle much enlarged and red in fruit ; leaves trifoliolate. 

 Receptacle not pulpy ; petals yellow. 

 Receptacle pulpy, edible ; petals white or pinkish. 

 Achenes 10-15 ; stamens 5 ; leaves trifoliolate. 

 Achenes hairy ; shrubs. 



Leaves trifoliolate ; style filiform ; flowers white. 

 Leaves pinnate ; style club-shaped ; flower (in ours) yellow. 

 Style nearly basal ; ovules ascending or nearly erect, orthotropous. 



Stamens and pistils numerous ; bractlets present ; leaves pinnate ; flowers 



large. 

 Stamens 5 ; pistils 5-10 ; bractlets not present ; leaves twice ternate ; flowers 

 small. 



1. Potentilla. 



2. Horkelia. 



3. Stellariopsis. 



4. Gomarella. 



Waldsteinia.^) 



5. Argentina. 



6. Comarum. 



7. Duchesnea. 



8. Fragaria. 



9. Sibbaldia. 



10. Sibbaldiopsis. 



11. Comocarpa. 



12. Drymocallis. 



13. Chamaerhodos. 



' Pittonia, 1 : 95-106. 



* Waldsteinia and the Siberian Coluria are sometimes placed in the Potentilleae on account of the styles which are articu- 

 lated to the ovary, sometimes in the Dryadeae on account of their basal erect ovules. 



