Dehiscence

Dehiscence, or splitting, a term applied, in botany, especially to the bursting of the anther or of the fruit. The anther generally dehisces longitudinally; but, when short, sometimes transversely; in the heath-tribe, more especially, by a terminal pore; and, in the barberry and the bay, by the formation of flap-like valves or opercula. Dehiscence, which accompanies the ripeness of the pollen, results from the absence of thickening bands in certain cells of the endothecium, or inner membrane of the wall of the anther. Among fruits, dehiscence is mainly confined to dry fruits containing more than one seed, the others being indehiscent. The succulent fruits of the horse-chestnut, balsam, walnut, and yellow water-lily are exceptional in being dehiscent. Fruits may dehisce by pores, as in the capsules of the poppy and snapdragon; transversely, as in the pimpernel (Anagallis) and plantain (Plantago); by teeth, as in Primula and the pinks; or longitudinally. The legume splits longitudinally down both sutures; the follicle, as in the larkspur, down the ventral suture only. Where the fruit is syncarpous, dry, and many-seeded, it splits into valves, which may each be a carpel or halves of two contiguous carpels.