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xi either discharges its perfected ovules through openinigs made in the vessel, or drops to the ground and decays, allowing the seeds to germinate. The mode of opening, technically called dehiscence, is often an important characteristic; non-opening seed-vessels are said to be indehiscent.

There is a great variety of form and structure in the fruit of plants; but we can here notice only some of the more frequent kinds. A dry fruit dehiscing by valvular openings or pores is termed a capsule, as in the Poppy and Foxglove. A siliqua is a capsule opening by two valves and leaving the seeds attached to a membranous frame or replum formed by the placentas in the centre, as in the Wall-flower and other Cruciferæ; when short and thick, it is called by some writers a silicula. A legume or pod is a fruit formed of one carpel bearing a row of seeds along the united margins of the leaf, and opening by both sutures, as in the Pea and Broom; the term pod, however, is often given to the siliqua of Cruciferæ and to other fruits which resemble the legume externally. A follicle is a pod opening only by the ventral suture, or that along which the seeds are attached, as in the Larkspur; it is usually produced in flowers bearing several pistils, two or more follicles constituting the fruit. Among the indehiscent varieties may be mentioned the achænium, a one-seeded carpel with a separable covering, generally, like the follicle, found several together, as in the Buttercup; the nut, a hard one-celled fruit, containing a single seed; the drupe, a fleshy fruit enclosing a nut-like seed-vessel, as in the Cherry; the berry, in which the seeds are imbedded in a pulpy mass, as in the Hawthorn fruit; and the pome or apple, where the adherent calyx forms, with the outer covering of the ovary, a succulent body in which are cells containing the seeds.

The seed consists of the embryo or young plant, surrounded usually by a quantity of matter stored up for its nutriment, called albumen, and enclosed in a testa or cuticle. The albumen is of various consistence,—farinaceous, as in Wheat; fleshy, as in the