ERICACEAE. 273 



Winter-character references: Rhododendron (Rhodora) 

 canadensis. Arnold! pictures a cross-section of the winter 

 bud in Flora, 87:466, f. 27. R. dahuricum. Schneider, f. 126. 

 R. dilatatum. Shirasawa, 284, pi. 13. R. ferrugineum. Ar- 

 noldi, Flora, 87:450, f. 8, bud-section. R. flavum. Schnei- 

 der, f. 95. R. (Azalea) procumrtens. Fant, 52. R. Schlippen- 

 bachii. Shirasawa, 284, pi. 13. R. sinensis. Shirasawa, 284, 

 pi. 13. 



1. Twigs with slender flat chaff-like scales rather than 



hairs. 2. 



Without chaff: sometimes pubescent or glandular-dot- 

 ted. 6. 



2. Evergreen or partly evergreen. 3. 



Deciduous: rather tall. R. Kaempferi. 



3. Leaves glossy above: low and compact. R. indicum. 

 Leaves dull. 4. 



4. Leaves moderate (2.5-5 cm. long), acute. R. indicum. 

 Leaves rather small (usually under 2-5 cm.). 5. 



5. Leaves acute: rather tall. R. Simsii. 

 Leaves typically obtuse: low, compact. (1). R. obtusum. 



6. Evergreen. 7. 

 Deciduous. 17. 



7. Leaves with large glandular dots beneath. 8. 

 Leaves glandless and glabrous beneath. 16. 



8. Loosely long-hairy: leaves small (1X2 cm.). R. hirsutum. 

 Twigs velvety. R. micranthum. 

 Glabrate except for the glandular scurf. 9. 



9. Leaves with scattered glands, green beneath. 10. 

 Leaves brown beneath from the glandular scurf. 11. 



10. Leaves rather obtuse, smooth-margined. R. dahuricum. 

 Leaves very acute, crisped. (2). R. mucronulatum. 



11. Leaves small (about 1 cm. long) : low. R. lapponicum. 

 Leaves much larger. 12. 



12. Leaves lanceolate, relatively narrow. 13. 

 Leaves ovate- or elliptical-lanceolate. 14. 



