Fig. 235.—Three-carpeled Fruit of Horse-chestnut. Two locules are closing by abortion of the ovules.
There are several ways in which capsules dehisce or open. When they break along the partitions (or septa), the mode is known as septicidal dehiscence (Fig. [236]); In septicidal dehiscence the fruit separates into parts representing the original carpels. These carpels may still be entire, and they then dehisce individually, usually along the inner edge as if they were follicles. When the compartments split in the middle, between the partitions, the mode is loculicidal dehiscence (Fig. [237]). In some cases the dehiscence is at the top, when it is said to be apical (although several modes of dehiscence are here included). When the whole top comes off, as in purslane and garden portulaca (Fig. [238]), the pod is known as a pyxis. In some cases apical dehiscence is by means of a hole or clefts.
Fig. 236.—St. John’s Wort. Septicidal.
Fig. 237.—Loculicidal Pod of Day-lily.
The peculiar capsule of the mustard family, or Cruciferæ, is known as a silique when it is distinctly longer than broad (Fig. [224]), and a silicle when its breadth nearly equals or exceeds its length. A cruciferous capsule is 2-carpeled, with a thin partition, each locule containing seeds in two rows. The two valves detach from below upwards. Cabbage, turnip, mustard, water-cress, radish, rape, shepherd’s purse, sweet alyssum, wall-flower, honesty, are examples.
Fig. 238.—Pyxis of Portulaca or Rose-moss.