328 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Rydberg, in his recent treatment of the genus in the North American Flora, recognizes 

 6 species in tliis group. The characters relied upon, however, are not at all convincing. 

 P. confusus Piper is considered a valid spt^cie^; P. columbianus Koehnea supposed to be 

 from British Columbia, is identified with specimens here referred to P. gordonianiis; and 

 P. angustifolius Rydberg^ is described from specimens collected at "Palace Camp" on 

 the Willis trail to Mount Rainier. 



ROSACEAE. Rose Family. 



Carpels few, in fruit becoming 2 to several-seeded follicles or capsules; 

 shrubs. 



Leaves palmatcly lobed; pods 2-valved Opulaster (p. 329). 



Leaves not palmatcly loWd. 



Stamens united at base; leaves twic« or thrice palmately 



3-cleft ; flowers racemose Lutkea (p. 329). 



Stamens not united at base ; flowers in panicles or corymbs. 



Stamineal disk adherent, entire; ovules 2 Sohizonotus (p. 330). 



Stamincal disk free at the edge, not entire; ovules 

 several. 



Shrubs with simple leaves; flowers perfect Spiraea (p. 330). 



Herbs with compound leaves; flowers dioecious. Aruncus (p. 332). 

 Carpels few to many, becoming akenes or drupelets in fruit. 



Fruit consisting of druplots, usually united RuBUS (p. 332). 



Fruit consisting of akenes. 



Akenes in fruit inclosed in the more or less enlarged tur- 

 binate or campanulate receptacle. 



Receptacle cup-shaped and fleshy in fruit; prickly 



shrubs with pinnate leaves Rosa (p. 334). 



Receptacle dry in fruit; herbs. 



Petals yellow ; calyx prickly Aqrimonia (p. 335). 



Petals none; calyx not prickly. 



Leaves palmately lobed; flowers axillary. . Alchemilla (p. 335). 



Leaves pinnate ; flowers spicate Sanouisorba (p. 335). 



Akenes in fruit on a plane or merely concave receptacle. 

 Herbs. 



Styles deciduous, naked, terminal or lateral. 

 Styles terminal. 



Stamens inserted near the base of the 

 receptacle cup on an annular thicken- 

 ing; flowers yellow Potentiixa (p. 336). 



Stamens inserted well up in the recep- ' 



tacle cup; no annular thickening IIorkelia (p. 339). 



Styles lateral. 



Carpels hairy; shrubs Dasiphora (p. 341). 



Carpels glabrous; herbs. 



Stamens 5; carpels 10 to 15; leaves 



trifoliolate Sibbaldia (p. 340). 



Stamens 20; carpels numerous. 

 Leaves trifoliolate; receptacle 



fleshy in fruit; petals white. Fragaria (p. 340). 

 Leaves pinnate; receptacle 

 not fleshy. 



aGartenflora 1896: 542. 1896. bN. Am. Fl. 22': 166. 1905. 



