Fig. 89.—Fruit of the Sweet Chestnut.

This is a very small genus, only containing two or three species, of which only one, the Sweet Chestnut (Castanea vesca) is common in England. This plant was included by Linnæus in the genus Fagus, but it appears very distinct. The male flowers are produced round a central axis, but so far apart as hardly to be like a

Fig. 88.—Chestnut (Castanea vesca). catkin (see a in fig. 88). These flowers in the bud look like little knobs, but when they open the stamens burst out, as shown at b. Each flower has a large and a small bract, and from ten to fifteen stamens. The female flowers are disposed in a tuft as shown at c, surrounded by a number of bracts and scales, which afterwards grow together and form a spiny involucre (see fig. 89 a,) which forms the husk of the ripe nuts (b), and opens into four valves as shown at c. Each female flower has a closely-fitting calyx, toothed at the tip, which afterwards becomes the hard brown skin that envelops the kernel of the ripe nut; and each flower is furnished with six styles, having as many cells with two ovules in each, though generally all the cells unite into one, and most of the ovules wither before the fruit ripens. There are three female flowers in each involucre, which lie nestling together like birds in a nest. When ripe the involucre or husk opens naturally into four valves (as shown in fig. 89), and drops the one or two Chestnuts which it contains. Each nut, when ripe, is enveloped in a brittle shining skin formed of the metamorphosed calyx, and consists of only one cell, in which are one, two, or at most three kernels, which are the seeds.

THE GENUS CORYLUS.

The Hazel Nut (Corylus Avellana) has the male and female flowers on the same tree; the male being in long catkins and the female ones in little oval buds, something like those of the Oak, (see a in fig. 90,) which are so small that they would hardly be seen on the tree, if it were not for their bright red stigmas. The

Fig. 90.—The Hazel
(Corylus Avellana.) male flowers (fig. 91) have each three bracts, one behind the two others, to the inner ones of which are attached eight stamens. As the buds containing the female flowers expand, two or three small leaves make their appearance between the scales (b in fig. 90), so