CUPULIFERÆ—THE CUP-BEARING TREES.
This order includes six genera of very important trees; all of which have their ripe fruit shrouded in a cup-like involucre, which they retain till ripe. The male and female flowers are on the same plant.
THE GENUS QUERCUS.
The fruit of all the species of Oak is an acorn, which is only partly covered by a scaly involucre called the cup. The shape of the acorn, and the height to which it is covered by the cup, differ in the different species; but the general character of both is always the same.
The male catkins of the common British Oak (Quercus Robur pedunculata) are long and very few flowered; the flowers being small and very far apart. The flowers themselves have six or eight stamens and as many feathery bracts, which are united at the base. The female flowers (a in fig. 85)
Fig. 85.—The Oak. are produced on a long stalk at a distance from each other, and each consists of an ovary closely covered with a toothed calyx, as shown in the highly-magnified flower at
Fig. 86.—Germination of the Acorn. (c), and an involucre of several bracts or scales, (d); the style is short and thick, and the stigma (e) is three-lobed. As the fruit ripens, the style and stigma wither away, and the seed remains covered by the adnate calyx (b), which has become hard and shining. There is a circular mark or scar at the bottom of the acorn when taken out of its cup, which is called the hilum; and when the acorn is planted, this part should be kept upwards, as the foramen or part where the germ lies is at the other end. When the acorn begins to germinate, it opens at the foramen, cracking a little about half-way down, but not dividing entirely (see fig. 86). The root (a) then begins to protrude, and soon after the plumule, or young shoot (b), the leaves of which gradually unfold themselves. A curious experiment may be tried by suspending an acorn in a glass of water, or by placing it in one of those glasses with a wide mouth and a narrow neck, used for nosegays; when, if kept in a sitting-room, the acorn will gradually open, and the root and leaves develop themselves; and thus may be watched the first beginning of the monarch of the forest, the progress of which is so strikingly depicted in the beautiful lines adapted by Cowper to the hollow trunk of a gigantic oak in Yardley Chase near Castle Ashby:—
Thou wert a bauble once, a cup and ball