HlPPOCASTANACEAE. 



207 



AESGULUS. Horsechestnut. Buckeye. 

 (Family Hippocastanaceae). 



Round-topped trees or excep- 

 tionally shrubs: deciduous. Twigs 

 stout, nearly terete: pith large, 

 rather 6-sided, continuous, pale. 

 Buds, especially the uppermost, 

 very large, solitary, ovoid, sessile, 

 with some half-dozen pairs of ex- 

 posed scales. Leaf-scars opposite, 

 low, shield-shaped or triangular: 

 bundle-traces 3 or in 3 compound 

 groups, exceptionally 7 or 9 in a 

 single series: stipule-scars lack- 

 ing. References under Koelreu- 

 teria. 



Meyer reports in volume 7 of 

 Linnaea exceptional superposed 

 buds in horsechestnut. A char- 

 acteristic feature of the bud- 

 scales is the rudimentary leaf, or 

 its scar, at the tip. As in Acer 

 and other genera with terminal 

 inflorescence, the twig may end 'in an inflorescence-scar. 



1. Buds gummy. (Hippocastanum, the horsechestnuts). 2. 

 Buds not gummy. (Pavia, the buckeyes). 3. 



2. Buds persistently gummy. (1). A. Hippocastanum. 

 Buds gradually becoming dry. (Hybrid h.). X A. carnea. 



3. Trees. 4. 

 Shrubs. 5. 



4. Bark rough, soft and cork-like. (Ohio b.). (2). A. glabra. 

 Bark smooth and firm. (Sweet buckeye). A. octandra. 



5. Lowest scale less than half as long as bud. A. Pavia. 

 Lowest scale half as long as bud. ( Shrubby b. ) . A. parviflora. 



