Fig. 139.—A, group of Hazel Nuts (× ½); B, longitudinal section of fruit.
The dispersal of nuts.—Squirrels and other nut-eating animals are instrumental in the dispersal of the seeds in a somewhat indirect manner. They have a habit of storing up nuts and seeds in holes; but in their active life these animals often forget where their larder is. The seeds, thus left to themselves, sprout and grow into trees. The unripe nuts of the beech are protected from the attacks of squirrels by the hard bristles on the outer husk.
Fig. 140.—A, Plum; B, longitudinal section; C, cross section; E, M, En, outer, middle, and inner layers of pericarp; S, seed. (× ½.)
Stone fruits.—A ripe plum ([Fig. 140]) or cherry ([Fig. 77]), like a nut, consists of a seed and a pericarp; but here the pericarp is specially modified to tempt animals and at the same time to protect the seed from them. The inner pericarp-layer is a hard, woody shell called the stone; the middle part swells up to form a juicy, sweet mass; while the outer layer constitutes the “skin,” and is often beautifully coloured.
Fig. 141.—
Blackberry.
(× 1.)
Blackberries ([Fig. 141] F) and raspberries consist of several small fruits of the plum type, which are arranged round an axis derived from the receptacle of the flower.