150 American Midland Naturalist Monograph No. 2 



low; in swamp, sandy, or limy soil, local, n.e. 111.; also in Jo Daviess Co. 



June-Aug. \Dasiophora jruticosa (L.) Rydb.} Shrubby Cinquefoil 



P. fniticosa L. 



1. Herbs; leaflets not entire. 



2. Petals maroon-purple, acute, shorter than the sepals; leaves pinnate, 5-7- 

 foliolate, the leaflets oblanceolate, serrate, 3-8 cm. long, glaucous beneath; 

 receptacle becoming spongy; bogs and swamps, Lake Co. June-July. 

 [Comarum palustre L.} Purple Cinquefoil P. palustris (L.) Scop. 



2. Petals yellow, white, or cream, obtuse or retuse; receptacle not becoming 

 enlarged and spongy. 

 3. Leaves pinnate. 



4. Flowers solitary on long pedicels; petals yellow; plants stoloniferous; 

 leaflets 7-21, with smaller intermediate ones, sharply serrate, whit- 

 ish silky-pubescent beneath; wet ground. Lake and Cook counties. 



May-Aug. [^Argentina anserina (L.) Rydb.] Silverweed 



^...P. anserina L. 



4. Flowers cymose; leaflets not whitish pubescent beneath; plants not 

 stoloniferous. 



5. Petals white or cream; flowers 12-20 mm. in diameter: stamens 

 30; style nearly basal; stem stout, 1-2 m. tall, glandular-pubes- 

 cent; gravelly soil, not common. June-July. [Drymocallis agr't- 

 monioides (Pursh) Rydb.; D. arguta (Pursh) Rydb.] Tail 

 Cinquefoil P. arguta Pursh 



5. Petals yellow; flowers 6-10 mm. in diameter; stamens 20; style 

 terminal; stem decumbent at base, 20-40 cm. tall; wet ground, 

 rare. St. Clair Co., Brendel P. paradoxa Nutt. 



3. Leaves palmate. 

 6. Flowers cymose. 



7. Leaflets silvery-pubescent beneath; petals 4-5 mm. long; sandy or 

 gravelly soil. May-Sept. Silvery Cinquefoil P. argenta L. 



7. Leaflets green on both sides. 



8. Leaflets 5-9; petals pale yellow, longer than the sepals; stamens 

 about 30; mature achenes reticulate; waste places and along 



roads; native of Eur. May-July. [P. sulphurea Lam.] 



P. recta L. 



8. Leaflets 3; petals deep yellow, shorter than the sepals; stamens 

 10-25; moist ground, common. June-July. Rough Cinque- 

 foil P- monspeliensis L. 



6. Flowers solitary, axillary, long-peduncled, 10-15 mm. in diameter; 

 leaflets 5, oblanceolate, serrate; stem slender, ascending or trailing; 

 roadsides, gravelly soil, etc., common. May-June. [P. canadensis 

 of auth., ex p.] Common Cinquefoil P. simplex Michx. 



7. FiLIPENDULA Mill. 

 F. rubra (Hill) B. L. Robins. Prairie Meadowsweet. Moist ground, not 



