Henry A. Gleason, The Plants of Michigan
“ Leaves thin, dull above; fruit black, large and juicy Dewberry, Rubus villosus. 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 stalk, while the lateral 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 deposit ”
