HIPPOCASTANACEAE. 207 
ArscuLtus. 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- 
seales 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.). < 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. 
