877. The capsule.—When the capsule is syncarpous it may dehisce in three different ways: 1st. When the carpels split along the line of their union with each other longitudinally (septicidal dehiscence), as in the azalea or rhododendron. 2d. When the carpels split down the middle line (loculicidal dehiscence), as in the fruit of the iris, lily, etc. 3d. When the carpels open by pores (poricidal dehiscence), as in the poppy. Some syncarpous capsules have but one locule, the partitions between the different locules when young having disappeared. The “bouncing-bet” is an example, and the seeds are attached to a central column in four rows corresponding to the four locules present in the young stage.
878. A follicle is a capsule with a single carpel which splits open along the ventral or upper suture, as in the larkspur, peony.
879. The legume, or true pod, is a capsule with a single carpel which splits along both sutures, as the pea, bean, etc. As the pod ripens and dries, a strong twisting tension is often produced, which splits the pod suddenly, scattering the seeds.
880. The silique.—In the toothwort, shepherd’s-purse, and nearly all of the plants in the mustard family the fruit consists of two united carpels, which separate at maturity, leaving the partition wall persistent. Such a fruit is a silique; when short it is a silicle, or pouch.
881. A pyxidium, or pyxis, is a capsule which opens with a lid, as in the plantain.
[IV. Fleshy and Juicy Fruits.]
882. The drupe, or stone-fruit.—In the plum, cherry, peach, apricot, etc., the outer portion (exocarp) of the pericarp (ovary) becomes fleshy, while the inner portion (endocarp) becomes hard and stony, and encloses the seed, or “pit.” Such a fruit is known as a drupe, or as a stone-fruit. In the almond the fleshy part of the fruit is removed.
Fig. 477.
Drupe, or stone-fruit, of plum.
883. The raspberry and blackberry.—While these fruits are known popularly as “berries,” they are not berries in the technical sense. Each ovary, or pericarp, in the flower forms a single small fruit, the outer portion being fleshy and the inner stony, just as in the cherry or plum. It is a drupelet (little drupe). All of the drupelets together make the “berry,” and as they ripen the separate drupelets cohere more or less. It is a collection, or aggregation, of fruits, and consequently they are sometimes called collective fruits, or aggregate fruits. In the raspberry the fruit separates from the receptacle, leaving the latter on the stem, while the drupelets of the blackberry and dewberry adhere to the receptacle and the latter separates from the stem.