106 ROSACEAE. 
Sorsus. 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, Torminaria). 
Winter-character references under 
Photinia. 
1. Bundle-traces three. 2. 
Bundle-traces three to five. 7. 
2. Buds subglobose. S. torminalis. 
Buds elongated. 3. 
3. Scales dark-margined. 4. 
Scales not dark-margined. 6. 
4. End-bud enlarged. S. Chamaemespilus. 
End-bud scarcely larger than lateral. 5. 
5. Buds of equal size. S. latifolia. 
Buds markedly unequal. (White Beam). (1). S. Aria. 
6. Scales with scarious-margins. S. Mougeotii. 
Scales not scarious-margined. S. alnifolia. 
7. Bundle-traces 3 or 4 or 5: buds woolly. (2). «5S. hybrida. 
Bundle-traces five. 8. 
8. Buds woolly, not gummy. (Rowan Tree). S. Aucuparia. 
Buds gummy. (Mountain Ash). (3). S. americana. 
