53 



17a. Stems distinctly shrubby and thorny (Dewberry) 18. 

 17b. Stems almost herbaceous, without thorns 



Dwarf Raspberry, Rubus triflorus. 



ISa. Leaves thin, dull above; fruit black, large and juicy 



Dewberry, Rubus yillosus. 



18b. Leaves firm or thick, shining above; fruit reddish, small, 

 consisting of a few sour drupelets 



Swamp Dewberry, Rubus hispidus. 



19a. Ripe fruit dropping away from the white receptacle or core; 

 terminal leaflet of each leaf with a long staik, while the lat- 

 eral leaflets are sessile or nearly so (Raspberry) 20. 



19b. Ripe fruit and receptacle or core dropping together; all the 

 leaflets on stalks which are approximately equal in length 

 (Blackberry) 22. 



20a. Stem very glaucous with a whitish or bluish waxy de- 

 posit; fruit black Black Raspberry, Rubus occidentalis. 



20b. Stem not glaucous; fruit red 21. 



21a. Calyx velvety-pubescent Red Raspberry, Rubus idaeus. 



21b. Calyx bristly-hispid 



Red Raspberry, Rubus idaeus var. aculeatissimus. 



22a. Pedicels with gland-tipped hairs, but no prickles 



Blackberry, Rubus alleg-lieniensis. 

 22b. Pedicels with prickles Blackberry, Rubus nigricans. 



22c. Pedicels with neither prickles nor gland-tipped hairs 23. 



23a. Leaves downy beneath Blackberry, Rubus frondosus, 



23b. Leaves smooth beneath Blackberry, Rubus canadensis. 



24a. Ovaries 1 or more, superior (attached to the surface of the 

 receptacle, but not concealed within it or united to it) 25. 



24b. Ovary 1, inferior (permanently enclosed within the re- 

 ceptacle, with only the styles protruding) 38. 



25a. Ovaries more than 1 26. 

 25b. Ovary 1 30. 



26a. Leaves serrate 27. 

 26b. Leaves lobed 28. 



27a. Leaves glabrous or very nearly so (8 20 dm. high; flowers 



white or pinkish, 'summer) 



Meadow-sweet, Spiraea salicifolia. 

 27b. Leaves closely pubescent beneath (5 15 dm. high; flowers pink, 



summer) Hardhack, Spiraea tomentosa. 



28a. Flowers showy, purple or white, 3 4 cm. broad 29. 

 ,28b. Flowers white, about 1 cm. wide (1 3 m. high; flowers in 

 early summer) Ninebark, Physocarpus opulifolius. 



