502 FLORA. 



lanceolate petals; bractlets much shorter than the calyx-lobes. In swamps and 

 peat-bogs, Greenland to Alaska, N. J., Mont., northern Cal. and Iowa. Also 

 in northern Europe and Asia. June -Aug. 



15. ARGENTINA Lam. 



Perennial herbs, with interruptedly pinnate leaves and long runners. Flowers 

 yellow, solitary on long pedicels from the axils of the basal leaves; petals broadly 

 oval or almost orbicular, not emarginate; stamens 20-25; style filiform, lateral, 

 tardily deciduous; mature achenes with a thick, corky pericarp; seed ascending, 

 amphitropous; otherwise as in Potentilla. A genus consisting of three species, 

 one from New Zealand and the following. 



Achenes thick, generally grooved at the upper end; leaves 1-2 dm. long; leaflets 

 sharply serrate. i. A. Anserina. 



Achenes lenticular ; leaves 3-5 cm. long ; leaflets with rounded teeth. 



2. A. Egedii. 



1. Argentina Anserina (L.) Rydb. SILVER- WEED. WILD OR GOOSE- 

 TANSY. (I. F. f. 1934.) Herbaceous; runners 3-10 dm. long. Stipules membra- 

 nous; leaflets 1-3 cm. long, oblong, oblanceolate or obovate, obtuse, the lower gener- 

 ally smaller, nearly glabrous above, white and silky-pubescent beneath; peduncles 

 about equalling the leaves ; flower yellow, 10-25 mm - broad ; petals exceeding the ovate 

 acute calyx-lobes and oval bractlets ; receptacle villous; achenes glabrous [Poten- 

 tilla Anserina L.]. On shores and salt meadows, N. J. to Greenland, west to Cal. 

 and Alaska, south in the Rocky Mts. to N. Mex. Also in Europe and Asia. 

 May-Sept. 



Argentina Anserina grandis (Torr. & Gray) Rydb. Leaves often 3-4 dm. long, 

 erect; leaflets oblong, 4-7 cm. long. In grassy places, from Greenland and Newf. to 

 Alaska, south to Mont, and Cal. 



2. Argentina Egedii (Wormsk.) Rydb. EGEDI'S SILVER-WEED. Much 

 smaller than the preceding; leaflets 5-15, glabrous above, sometimes white-tomen- 

 tose beneath, but never silky, broadly obovate or suborbicular, 5-10 mm. long; 

 pedicels 1-3 cm. long. [Potentilla Egedii (Wormsk.) T. & G.] Greenland to 

 Alaska, south to Mass, and Ore., along the coast. Also in Iceland. 



16. POTENTILLA L. 



Herbs or shrubs, with alternate stipulate digitately or pinnately compound 

 leaves, and cymose or solitary, yellow white or purple perfect flowers. Calyx 

 persistent, its tube concave or hemispheric, 5-bracteolate (rarely 4-bracteolate), 

 5-lobed (rarely 4-lobed). Petals 5 or rarely 4, mostly obovate or orbicular, usually 

 emarginate. Stamens 20-30, seldom 5 or 10; filaments slender ; anthers small. 

 Carpels usually in 3 series, numerous, inserted on a dry, usually pubescent recep- 

 tacle; style terminal, deciduous. Seed pendulous and anatropous. [Diminutive 

 oipotens, powerful, from the medicinal properties of some species.] About 150 

 species, nearly all natives of the north temperate zone. Besides the following 

 about 30 others occur in western N. Am. All species of our range have yellow 

 flowers and glabrous achenes. 



I. Flowers cymose ; erect or ascending herbs. 



Leaves digitately 3-7-foliolate; leaflets dentate or incised. 

 . Leaflets 5-7. 



Leaves white- pubescent beneath. i. P. argentea. 



Leaves green beneath. 



Plant 7-20 cm. high; leaflets obovate, 12-16 mm. long; arctic. 



2. P. maculata. 

 Plants 3-8 dm. high ; leaflets 2-8 cm. long; introduced species. 



Leaflets obovate ; flowers 6-8 mm. broad. 3. P. intermedia. 



Leaflets oblanceolate: flowers 12-70 mm. broad. 4. P. sulphurga. 

 Leaflets 3 (or apparently 5 in no. n). 



Styles filiform ; plants arctic or alpine. 



Leaves white-pubescent beneath. 5. P. nivea. 



Leaves green beneath, often villous. 

 Flowers 10-14 mm. broad. 



