106 



ROSACEAE. 



SORBUS. Mountain Ash. 

 (Family Rosaceae). 



Rather erect-branched, small or 

 moderate trees: deciduous. Twigs 

 moderate, with rather large lenti- 

 cels, nearly terete: pith roundish, 

 brownish, continuous. Buds sub- 

 conical or oblong, the terminal 

 rather large and the lateral often 

 much reduced, solitary, sessile, 

 with several scales, the inner of 

 which are more or less pubescent 

 with long hairs often matted in 

 gum. Leaf-scars alternate, raised, 

 crescent-shaped or linear: bundle- 

 traces 3 or 5 or exceptionally 7: 

 stipule - scars lacking. ( Cormus, 

 Hahnia, Micromeles, Torminarm}. 

 Winter-character references under 

 Photinia. 

 1. Bundle-traces three. 2. 



Bundle-traces three to five. 7. 

 S. torminalis. 



2. Buds subglobose. 

 Buds elongated. 3. 



3. Scales dark-margined. 4. 

 Scales not dark-margined. 6. 



4. End-bud enlarged. 



End-bud scarcely larger than lateral. 



5. Buds of equal size. 



Buds markedly unequal. (White Beam). 



6. Scales with scarious-margins. 

 Scales not scarious-margined. 



7. Bundle-traces 3 or 4 or 5: buds woolly. 

 Bundle-traces five. 8. 



8. Buds woolly, not gummy. (Rowan Tree). 



Buds gummy. (Mountain Ash). 



S. Chamaemespilus. 

 5. 



S. latifolia. 

 (1). S. Aria. 

 S. Mougeotii. 

 S. alnifolia. 

 (2). x S. hybrida. 



S. Aucuparia. 



(3). S. americana. 



