13. Potentilla Anserina L. Silverweed. Fig. 495. 



Leaves and peduncles in a basal tuft from a cluster of roots (main stem almost 

 none) producing numerous runners 3-6 dm. long; leaves 1-2 dm. long, pinnate 

 with 9 to 3 I larger leaflets and smaller ones interposed, spreading or flat on the 

 ground; main leaflets obovate to oblong, rounded, sharply and coarsely serrate, 

 usually 1-3.5 cm. long, silky and green above, white-silky and tomentose beneath; 

 flowers 1-2 cm. in diameter, with pedicels 3-10 cm. long; bractlets simple and 

 lanceolate or often broader and ovate-lanceolate, toothed or divided, generally 

 a little longer than the broadly ovate sepals; petals yellow, oval, 7—10 mm. long; 

 stamens 20 to 25; achenes numerous, corky, grooved at upper end. Incl. var. 

 concolor Ser.; Argentina Anserina (L.) Rydb.; A. argentea Rydb. 



Marshy or springy places, wei meadows, pond and lake margins, mud flats 

 and stream banks, in N. M. (widespread in mts.) and Ariz. (Apache, Coconino 

 aad Greenlee cos.), May-Aug.; widely distributed in cooler parts of N. Hemis. 



The sweetish roots are said to be edible either raw or cooked. 



6. Geum L. Avens 



Perennial rhizomatous herbs with pinnate or lyrate leaves; flowers few, soli- 

 tary (in ours); calyx campanulate or deeply 5-cleft, usually with 5 small bract- 

 lets at the sinuses; petals 5; stamens numerous; achenes numerous, crowded on 

 a conical or cylindrical dry receptacle, the long-persistent styles forming hairy or 

 naked and straight or jointed tails; seed erect. 



About 40 species, mostly in the North Temperate Zone. 



1. Sepals reflexed at anthesis; hypanthium saucer-shaped, usually lined with a 

 glandular disk at least on the lower half; styles strongly geniculate 

 and jointed, the persistent lower portion hooked at the tip (2) 



1. Sepals ascending to erect at anthesis; hypanthium turbinate to bowl-shaped, 



the lower half usually not disk-lined; styles often neither geniculate 

 nor jointed and hooked on the persistent portion (4) 



2(1). Petals white or sometimes very pale-yellow; distribution in eastern Okla- 

 homa and eastern Texas 1. G. canadense. 



2. Petals golden-yellow; distribution in mountains of New Mexico and Arizona 



(3) 



3(2). Lower persistent portion of the style without glands, glabrous or slightly 

 hirsute near the base; terminal segment of the basal leaves some- 

 what larger than the main lateral lobes but similarly cuneate-based 

 2. G. aleppicum. 



3. Lower persistent portion of the style somewhat glandular-pubescent; terminal 



segment of the basal leaves many times larger than the main lateral 



lobes and usually rounded to subcordate at base 



3. G. macrophyllum. 



4(1). Petals erect to convergent, the flower somewhat vase-shaped; cauline leaves 



2 or rarely 4, opposite, their bases more or less sheathing 



4. G. triflorum. 



4. Petals spreading or at least not erect or convergent, the flower more nearly 



rotate; cauline leaves 1 to several, alternate (5) 



5(4). Style strongly geniculate and jointed, the terminal portion eventually 

 deciduous, the persistent lower portion hooked at the tip; hypan- 

 thium bowl-shaped; basal leaves lyrate-pinnatifid, the segments 7 

 to 15; plants mostly 4-6 dm. tall 5. G. rivale. 



5. Styles straight or only slightly bent, not jointed, persistent on the achene; 



hypanthium shallowly funnelform; basal leaves interruptedly 



pinnatifid, with 9 to 31 segments; plants rarely over 3 dm. tall 



6. G. Rossii. 



1031 



