ROSACEAE 105 



counties, and to the Apple River Canyon in the extreme north- 

 western corner of the state. Formerly, it must have been very 

 abundant near Chicago, Ravenswood, Elgin and Waukegan. 

 Probably it has been largely destroyed and now may be a 

 fairly rare plant. 



RUBUS (Tournefort) Linnaeus 

 The Brambles: Raspberries, Blackberries, Dewberries 



The brambles are chiefly shrubs with trailing, erect, or curved 

 branches. A few are herbaceous. The woody forms are peren- 

 nial and have stems armed with prickles or bristles, or both. 

 The stems are biennial, simple and unbranched the first year 

 but the second year develop side branches which bear fruit. 

 The leaves are alternate and may be either simple or compound 

 and composed of 3 or 5 leaflets. Flowers are borne in racemes 

 or corymbs and are chiefly white, with 5 green sepals and 5 

 petals. The stamens and the ovaries are many, and the fruit 

 is an edible aggregate of fleshy carpels. 



Between 1,500 and 2,000 species have been described in this 

 genus, which is world wide in distribution. But there is much 

 overlapping of species, with resultant confusion in charac- 

 teristics, so that professional opinion varies greatly, both as to 

 what may constitute a species and as to the number of species 

 properly recognizable. 



The brambles are divisible into three general groups which 

 are relatively easily recognized: raspberries, the ripe fruit of 

 which separates as a hollow shell from the receptacle on which 

 it is borne; blackberries, the fruit of which does not separate 

 from its receptacle ; and dewberries, which have the same kind 

 of fruit as the blackberries but which have stems that, in their 

 second year, are trailing, rather than erect or curving. 



Key to the Bramble Species 



Leaves simple, but usually more or less lobed. . R. odoratus, p. 106 

 Leaves compound, consisting of 3 to 5 leaflets. 



Leaves white-tomentose beneath, fruit parting from the recep- 

 tacle (raspberries). 

 Stems prickly and glaucous, fruit black R. occidentalis, p. lOS 

 Stems bristle armed, not glaucous, fruit red. 



Plants not glandular-hispid; inflorescence finely villous 



R. idaeus, p. 108 



