102 ELEMENTS OF BOTANY. 



IV. RUBUS. 



Shrubs ; stems usually prickly ; leaves ample, 3-5-lobed or 

 compound ; calyx bractless, concave or nearly flat, 5-parted ; 

 petals 5 ; stamens numerous ; pistils numerous, forming small 

 drupelets which are inserted on an elongated receptacle to 

 form an aggregated fruit, style deciduous. 



1. R. occiDENTALis L. Black Raspberry. Stems long and 

 slender, often recurved and rooting at the tix)S, armed with weak, 

 hooked prickles ; leaves petioled, 3-5-foliate, leaflets ovate, coarsely 

 serrate, white-downy below ; flowers white, in compact terminal 

 corymbs ; pedicels erect or ascending ; fruit black, hemispherical, 

 separating easily from the receptacle. April-May. Common on 

 borders of woods northward, widely cultivated. 



2. R. STRiGOsus Michx. Red Raspberry. Stems widely 

 branching, biennial, not rooting at the tips, armed with weak bristles 

 and with a few hooked prickles ; leaves petioled, 3-5-foliate ; leaflets 

 ovate, acuminate, sharply serrate and sometimes lobed, pubescent 

 beneath ; flowers in terminal and axillary racemes and panicles, 

 pedicels drooping ; fruit hemispherical or conical, red, separating 

 easily from the receptacle. April-May. Common on mountains and 

 burned clearings in the northern section and widely cultivated. 



3. R. ARGUTus Bailey. Blackberry. Stem shrubby, erect or 

 bending, 4-10 ft. high, glandular-pubescent above and with stout, 

 hooked prickles below ; leaves petioled, 3-7-foliate, leaflets ovate, 

 acute, irregularly serrate, smooth or soft hairy ; flowers in terminal, 

 bracted panicles ; petals white, obovate, much longer than the acu- 

 ming,te sepals ; fruit large, black, oblong, adhering to the receptacle. 

 March-May. Common in thickets. 



4. R. cuneifolius Pursh. Sand Blackberry. Stem shrubby, 

 erect or diffuse, 2-3 ft. high ; prickles straight or recurved ; leaves 

 petioled, 3-5-foliate, leaflets obovate, serrate towards the apex, 

 cuneate towards the base, rough above, white tomentose beneath ; 

 racemes mainly terminal, few-flowered ; petals white, longer than 

 the sepals ; fruit ovoid, black, adhering to the receptacle, smaller 

 than the preceding. March- April. Common in old fields. 



5. R. TRiviALis Michx. Dewberry. Stem trailing or prostrate, 

 often several feet in length, armed with small, straight or recurved 

 prickles, and often thickly set wdth bristles ; leaves petioled, mostly 

 3-foliate ; leaflets ovate-lanceolate or oval, acute, sharply serrate, 

 smooth ; flowering branches commonly erect, few-flowered, flowers 

 large, white ; fruit black, adhering to the receptacle. March- April. 

 Common on dry, sandy soil. 





