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Æsculus plantierensis, André, a supposed hybrid between Æsculus carnea and Æsculus Hippocastanum, will be mentioned under the former species. Æsculus versicolor, Dippel, a hybrid between Æsculus Pavia and Æsculus octandra, will be treated under the latter species.

 

The following key to the species in cultivation is based on the characters of the leaves and buds. In Plate 61 the leaves of all these species are shown; and in Plate 62 are represented the twigs and buds of six species, viz., Hippocastanum, carnea, indica, glabra, octandra, and californica:—

A. Leaflets sessile or nearly so; buds very viscid.

1. Æsculus Hippocastanum.

Petioles glabrescent. Leaflets obtusely and irregularly serrate.

2. Æsculus turbinata.

Petioles pubescent, especially towards their tips. Leaflets regularly and crenately serrate.

B. Leaflets stalked.

* Buds viscid.

3. Æsculus indica.

Leaflets finely and sharply serrate, pale beneath. Buds very viscid.

4. Æsculus carnea.

Leaflets obtusely and irregularly serrate. Buds only slightly viscid, the brown scales having a dark-coloured margin.

5. Æsculus californica.

Leaflets shallowly and crenately serrate, pale beneath. Buds viscid, glistening with white resin.

** Buds not viscid.

6. Æsculus parviflora.

Leaflets densely grey-tomentose beneath, finely serrate in margin. Buds minutely pubescent.

7. Æsculus octandra.

Leaflets pubescent beneath, broadly lanceolate, shortly acuminate, with twenty or more pairs of nerves in the terminal leaflet; margin finely serrate but not usually ciliate. Petioles without jagged marginal ridges.

8. Æsculus glabra.

Leaflets glabrous beneath, except for a slight pubescence along the midrib and tufts in the axils, long-acuminate, with about fifteen pairs of nerves in the terminal leaflet, finely serrate with ciliate tufts in the bases of the serrations. Petioles with smooth marginal ridges.

9. Æsculus Pavia.

Leaflets slightly pubescent beneath, narrowly lanceolate, finely serrate but not ciliate in margin. Petioles flattened on the upper side, with marginal sharp ridges, usually jagged.