20. POTENTILLA L,. Sp. Pl. 495. 1753. 
Tormeniilla I. Sp. Pl. 500. 1753. 
Quinquefolium (Tourn.) Adans, Fam, Pl. 2: 295. 1763. 
Pentaphyllum Gaertn. Fruct. 1: 349. 1788. 
Tridophyllum Neck. Elem. 2: 93. 1790. 
Dactylophylium Spenn. Fl. Frib. 1084, in part. 1829. 
Potentillopsis Opiz, Lotos 7: 30. 1857. 
Chamaephyton Fourr. Ann. Soc. Linn. Lyon II. 16: 371. 1868. 
Dynamidium Fourr. Ann. Soc. Linn. Lyon II. 16: 371. 1868. 
Hypargyrium Fourr. Ann. Soc. Linn: Lyon II. 16: 371. 1868. 
Callionia Greene, Leaflets 1: 238. 1906. 
Annual or perennial herb, in the latter case usually with elongate, scaly, more or less 
cespitose rootstocks. Leaves pinnately or digitately compound. Inflorescence usually cy- 
mose-paniculate. Hypanthium concave, mostly hemispheric. Bractlets, sepals, and petals 
5 (sometimes 4), the petals deciduous, obcordate, obovate, rotund, or cuneate, as a rule not 
unguiculate, obtuse or emarginate, yellow, white, or dark-purple. Stamens most commonly 
20, in three series, viz., 10,5, and 5, respectively, sometimes more, sometimes fewer, inserted 
not very far from the receptacular column; anthers generally more or less didymous; fila- 
ments filiform or subulate, neither flattened nor dilated. Receptacle hemispheric or conic, 
bearing numerous pistils (in P. Lemmonii only 5-10, in a few others 10-20). Style often 
long and filiform, sometimes short and thickened at the base, always attached near the apex 
of the ovary, articulated to it and deciduous. Seeds inserted near the base of the style, 
pendulous and anatropous. 
Type species, Potentilla reptans L.' 
Flowers solitary, axillary, on long pedicels. 
Leaflets not tomentose beneath. I, TORMENTILLAE. 
Leaflets white-tomentose beneath. XIII. LONGIPEDUNCULATAE. 
Flowers cymose. ‘ 
Cymes very leafy, many-flowered. 
Bractlets usually 3-lobed. II, HETEROSEPALAE. 
Bractlets entire. 
Annuals or biennials, rarely short-lived perennials ; 
styles fusiform and glandular at the base. 
Leaflets merely toothed. III. SuPINAE. 
Leaflets deeply dissected. IV. ARENICOLAE. 
Perennials ; styles filiform but short, not glandular. V. ARGENTEAE. 
Cymes not very leafy, generally rather few-flowered. 
Flowers dark-red or dark-purple. XVIII. RuBRAE. 
Flowers yellow or whitish. 
Leaves digitate. 
Basal leaves 5-9-foliolate. ; 
Basal leaves without an additional pair of leaflets 
on the petioles. : 
Leaflets neither thick nor coriaceous. (Mostly 
species of temperate North America.) 
Plants more than 2 dm. high. : 
Leaves green on both sides, sparingly 
' hairy, not at all tomentose. 
Stamens about 30; mature achenes 
reticulate. (Introduced species.) VI. RECTAE. 
Stamens 20, rarely 25; achenes smooth. 
(Native species.) 
Bractlets elliptic or oval; stem very 
slender and weak; leaves very 
thin, almost glabrous. . VII, HEPTAPHYLLAE. 
Bractlets lanceolate ; stem stiff; Mey. 
leaves firmer. VIII. NUTTALLIANAE. 
Leaves either densely hairy or more or 
less tomentose beneath. 
Leaflets merely crenate or cut-toothed, 
the toothing not extending half- 
way to the midrib. : 
1As Linnaeus’ genus Potentilla (see Genera Plantarum) was based primarily on Tourne- 
fort’s Quinquefolium, the type of the latter becomes the type of the former. 
VoLumE 22, Part 4, 1908] 293 
