174 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



2. SPIRAEA L. 



Flowers about 1 em. wide, on slender pedicels 1. S. pruuifolia. 



Flowers small, in close clusters. 



Leaves thin, glabrous - -2. S. latifolia. 



Leaves thick, woolly beneath 3. S. tomentosa. 



1. Spiraea prunifolia Sieb. & Zucc. 



Cultivated and sometimes escaped. Apr. Originally from Japan. 

 Flowers often double. 



2. Spiraea latifolia (Ait.) Borkh. Meadowsweet. 

 Rocky places; infrequent. July. Northern states, south to Va. 



3. Spiraea tomentosa L. Hakdhack. 

 Low ground; rare; Sligo Creek (Oldys); southwest of Rockville (Hitchcock). July, 



Northern states, south to Ga. 



3. ROSA L. Rose. 



Leaflets 3-5; styles coherent in a protruding column 1. R. setigera. 



Leaflets 5-many; styles distinct. 



Calyx lobes deeply incised, erect on the fruit, persistent 2. R. canina. 



Calyx lobes deciduous, spreading 



Leaflets finely and evenly serrate 3. R. palustris. 



Leaflets coarsely .serrate. 



Infrastipular spines slender, nearly straight 4. R. virginiana. 



Infrastipular spines stout, with a broad base, curved 5. R. rubiginosa. 



1. Rosa setigera Michx. Climbing rose. 

 Thickets; infrequent. June. Eastern U. S. 



2. Rosa canina L. Dog rose. 

 Thickets and roadsides; rare. May. Cultivated in gardens; originally from Eur.; 



escaped in the eastern II. S. 



3. Rosa palustris Marsh. Swamp rose. 

 Borders oi swamps and streams; frequent, June. Eastern IT. S. (R. Carolina of 



authors, not L.) 



4. Rosa virginiana Mill. 



Borders of swamps; frequent. June. Northern states, south to Md. {R. lucida 

 Ehrh.) 



5. Rosa rubiginosa L. Sweetbrier. 

 Rocky places and open ground; frequent. Juue. Introduced from Eur. 



4. RTIBUS L. 



Leaves simple, 3-5-lobed; flowers 3-6 cm. wide, purple-red 1. R. odoratus. 



Leaves compound; flowers while. 

 Fruit falling away whole from the dry receptacle; petals shorter than the calyx; 



plant conspicuously glaucous 2. R. occidentalis. 



Fruit not separating from the juicy receptacle; petals longer than the calyx; plants 

 not conspicuously glaucous. 

 Stems erect or ascending, not prostrate or trailing. 

 Leaves wedge-shaped at base, pale- velvety beneath; pedicels armed with 



prickles 3. R. cuneifolius. 



Leaves not conspicuously wedge-shaped nor pale-velvety beneath; pedicels 



unarmed 4. R. argutus. 



Stems prostrate or trailing. 

 Stems armed with numerous weak prickles, these not confined to the angles. 



5. R. hispidus. 

 Stems armed with stout prickles on the angles 6. R. procumbens. 



