44 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 



17. Potentilla Michoacana. 



Spreading from an annual root, finely pubescent, divergently branched. Leaves ternate with 

 shortly stalked terminal leaflets ; leaflets narrowly cuneate, few-toothed above the middle, 1-2 cm. 

 long, finely puberulent. Bractlets oblong, about equalling the broadly ovate sepals. Petals white, ob- 

 ovate, truncate, half the length of the sepals. Stamens 5. 



Mexico, State of Alichoacan : C. G. Pringle, No. 5291. 1892. 



18. Potentilla biennis Greene. 



Potentilla rivalis var. millegrana Torr. U. S. Expl. Exp. 11: 289. Not Wats. 



Coulter. U. S. Geol. Surv. 1872: 765; Coville, Cont. U. S. Nat. Herb. 4: 96. 



(?) Potentilla millegrana Dougl.; Hook. Fl. Bor. Am. 1: 193, as synonym under P. 

 NoTvegica. 



Potentilla millegrana Wats, in King's. Eep. 5 : 85. In part. 1871. Not Engelm. 

 1849. Holzinger, Cont. U. S. Nat. Herb. 3: 223. 



Potentilla biennis Greene, Fl. Fran. 1 : 65, 1891 ; Man. Bay Keg. 115. 



Potentilla lateriflora Rydberg, Bull. Torr. Bot. Club, 23 : 261. 1896. 



Potentilla millegrana lateriflora Engelm. Rydberg, /. c. as synonym. 



Illustrations; Plate 9, f. 1; dissection of flower, /. 2; pistil,/ 3; stamen, /. 4; 

 fruiting hypanthium and calyx, /. 5. 



Annual or biennial. Stems often several from the root, 3-5 dm. high, terete, finely 

 and rather densely granular-pubescent, often tinged with red or purple, simpler than in 

 related species and with erect branches. Stipules small, ovate or oblong, entire or 

 toothed. Leaves all ternate, the lower with petioles 2-10 cm. long, more or less hairy; 

 leaflets broadly obovate, coarsely crenate, 2-4 cm. long and 1-3 cm. wide, the teeth 

 often mucronulate. Flowers small, about 5 mm. in diameter, on pedicels 5-15 mm. long 

 from the axis of upper leaves, making the branches finally resemble leafy racemes. 

 Hypanthium glandular-pubescent, in fruit about 5 mm. in diameter. Bractlets ovate- 

 lanceolate or oblong, acute, a little shorter than the ovate acute sepals. Petals yellow, 

 obovate-cuneate, sometimes slightly emarginate, shorter than the sepals. Stamens about 

 10. Pistils very numerous ; style terminal, thickened and glandular at the base; ripe 

 achenes whitish, smooth. 



This most resembles P. leucocarpa and is often confounded with it in our herbaria. 

 Sometimes it is labelled P. Norregica, which it resembles in the form of the leaf and 

 general habit, but is a much more slender plant and has much smaller petals and fruit- 

 ing calyx. From P. leucocarpa it differs in the simpler and erect stems, erect branching, 

 falsely racemose inflorescence, broader and more hairy leaflets, and more glandular stems. 



