This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Noble trees with opposite exstipulate digitately 5- to 9-folio-late deciduous leaves and terminal panicles or racemes of usually showy flowers. Flowers polygamous, irregular. Sepals and petals 4 or 5. Stamens 5 to 8. Capsule coriaceous, prickly or smooth, 3-lobed or globose, 3- (or by abortion 1- or 2-) celled; seeds large, resembling the fruit of the edible Chestnut. There are about fourteen species, from North America, the mountains of Central America and Asia. From esca, food. Pavia was-separated on account of the capsule being naked, but this character is uncertain and variable.
1. AE. Hippocastanum (fig. 64). Horse Chestnut. - This highly ornamental tree needs no description. It is supposed to be a native of Asia, and was introduced into Europe some three centuries ago. There is a double-flowered variety, and also variegated and other varieties, differing in the leaves being more or less lobed or cut.
2. AE. rubicunda, syn. AE. coccinea, AE. carnea. Scarlet-flowered Horse Chestnut. - The origin of this is obscure; by some it is averred to be from North America, and by others a garden variety of the preceding. However that may be, it is a beautiful tree, differing in its smaller stature and more rounded head from the common one. There are several varieties referred to this, but none of them probably superior to the type.
3. AE. Indica. - A very handsome though still very rare tree. Leaves very large, glabrous, 7- to 9-foliolate; leaflets obovatelanceolate, serrate, petiolulate. Flowers numerous, in terminal thyrsoid panicles; lower petals white tinged with red, upper yellow and red bordered with white. Fruit unarmed. A native of North India.
Fig. 64. AEsculus Hippocastanum. (1/4 nat. size.)
4. AE. glabra. - This species has even larger foliage than the common one, and white or greenish yellow flowers, but it is a very shy bloomer, and only desirable in a collection. Fruits either smooth or prickly. A native of North America.
AE. Ohiotensis and AE, pallida are scarcely distinguishable even as varieties.
5. AE. Pavia (fig. 65), syn. Pavia rubra. Red Buckeye. - A small relatively slender tree with reddish flowers. There are varieties of this named respectively humilis, pendula, lacini-ata., etc. All from North America.
Fig. 65. AEscuIus.Pavia. (1/4 nat. size.)
6. AE. Californica. - This is the handsomest of the North American species referred to Pavia. It is a tree 12 to 15 feet high, forming a dense head, which is literally covered with panicles of white highly fragrant flowers about the month of May.
Besides the foregoing, there are several other North American species occasionally grown in collections; as, A. fiava, Sweet Buckeye, a tree or shrub with yellowish flowers and included stamens, of which AE, purpurascens, syn. AE. discolor, is a variety, having the flowers tinged with red or purple; and AS, macrostachya is a shrubby species, remarkable for its long slender racemes of yellowish-white flowers.