XL VIII. ROSACE^E. 251 



minute, subulate; sep. spreading, long-acuminate, shorter than the narrow-obo- 

 vate, emarginate petals; sty. 00. A delicate house-plant, with* snow-white 

 double flowers. Native of Mauritius. 



12. POTENTILLA. 



Lat. potentia, power; in allusion to its supposed potency in medicine. 



Calyx concave, deeply 4 5-cleft, with an equal number of alter- 

 nate, exterior segments or bracteoles ; petals 4 5, obcordate ; sta- 

 mens 00 ; filaments slender ; ovaries collected into a head on a small, 

 dry receptacle ; styles deciduous ; achenia 00. Herbaceous or shrubby. 

 Lvs. pinnately or palmately compound. Pis. solitary or cymose, mostly 

 yellow. 



* Leaves palmately trifoliate. 



1. P. NORVEGICA. Norwegian Potentilla or Cinquefoil. 



Hirsute ; st. erect, dichotomous above ; Ifts. 3, elliptical or obovate, den- 

 tate-serrate, petioJulate; cymes leafy ; ^.exceeding the emarginate petals. 

 Old fields and thickets, Arc. Am. to Car. Stem 1 4f high, covered with silky 

 hairs, terete, at length forked near the top. Cauline petioles shorter than the' 

 leaves. Leaflets 1J 7 by j ', (lower and radical ones very small,) often 

 incised. Stipules large, ovate, subentire. Flowers many, crowded, with pale 

 yellow petals shorter than the lanceolate, acute, hairy sepals. Jl. Sept. 



0. ? tdrsuta. T. & G. (P. hirsuta. Michx.) Hairs loose, silky ; st. slender, 

 erect, subsimple ; lower and middle Ivs. equal, long-petiolate ; Ifts. roundish-obo- 

 vate, sessile, incisely dentate ; fls. few, petals rather conspicuous, nearly as long 

 as the calyx. Dry fields. With reluctance I adopt the views of Torrey & Gray 

 in regard to this plant. 



2. P. TRIDENTATA. Ait. Trident or Mountain Potentilla. 



Smooth ; st. ascending, woody and creeping at base ; Ifts. 3, obovate-c"une- 

 aU,, evergreen, entire, with 3 large teeth at the apex ; cymes nearly naked ; pet. 

 twice longer than the calyx. On the White Mis. ! and other alpine summits in 

 the N. States. Flowering stems 6 12' high, round, often with minute, ap- 

 pressed'hairs. Petioles mostly longer than the leaves. Leaflets sessile, 9 18" 

 oy 4 6", coriaceous, smooth. Flowers with white, obovate petals. Carpels 

 and achenia with scattered hairs. Jn. Jl. 



3. P. MINIMA. Haller. 



St. pubescent, ascending, mostly 1-flowered ; Ivs. trifoliate 5 Ifts. obovate, 

 obtuse, incisely serrate, with 5 teeth above ; pet. longer than the sepals. 

 Alpine regions of the White Mts. Stems numerous and leafy, 1 3' high. 

 Leaflets with the margins and veins beneath hairy. Flowers small.- Petals 

 obcordate. Bracteoles oval-obtuse, narrowed at the base. 

 * * Leaves palmately 3 or b-foliate. 



4. P. CANADENSIS. (P. sarmentosa. Willd.') Common Cinquefoil. 



Villose pubescent ; st. sarmentose, procumbent and ascending ; Ivs. pal- 

 mately 5-foliate, the leaflets obovate, silky beneath, cut-dentate towards the 

 apex, entire and attenuate towards the base; slip, hairy, deeply 2 or 3-cleft, or 

 entire; pedicels axillary, solitary; bracteoles of the calyx longer than the seg- 

 ments, and nearly as long as the petals. Common in fields and thickets, U. S. 

 and Can. Stems more or less procumbent at base, from a few inches to a foot 

 or more in length. Flowers yellow, on long pedicels. Calyx segments lanceo- 

 late or linear. Apr. Aug. 



p. pumila. T. & G. (P. pumila. PA.) Very small and delicate, flowering 

 in Apr. and May. I cannot perceive any difference between this and the above, 

 except its diminutive size and early flowering. In dry, sandy soils. Stems 

 about 3' high. 



y. simplex. T. & G. (P. simplex. Michx.} Plant less hirsute ; st. sirjple, 

 erect or ascending at base; lfl.s. oval- cuneiform; flowering in June Aug In 

 richer soils. Sterns 8 14' high. Leaflets about 1' long, f as wide. 



5. P. ARGENTEA. Silvery Cinquefoil. 



St. ascending, tomentose, branched above; lff.s. oblong-cuneiform, with a 



