Fig. 33.—Silicula or pouch of shepherd’s purse (Capsella), opening by two folded valves, which separate from above downwards. The partition is narrow, hence the silicula is angustiseptal.
From Strasburger’s Lehrbuch der Botanik, by permission of Gustav Fischer.
Fig. 34.—Fruit of the pine-apple (Ananassa sativa), developed from a spike of numerous flowers with bracts, united so as to form a collective or anthocarpous fruit. The crown of the pine-apple, c, consists of a series of empty bracts prolonged beyond the fruit.
The same causes which produce alterations in the other parts of the flower give rise to anomalous appearances in the fruit. The carpels, in place of bearing seeds, are sometimes changed into leaves, with lobes at their margins. Leaves are sometimes produced from the upper part of the fruit. In the genus Citrus, to which the orange and lemon belong, it is very common to meet with a separation of the carpels, so as to produce what are called horned oranges and fingered citrons. In this case a syncarpous fruit has a tendency to become apocarpous. In the orange we occasionally find a supernumerary row of carpels produced, giving rise to the appearance of small and imperfect oranges enclosed within the original one; the navel orange is of this nature. It sometimes happens that, by the union of flowers, double fruits are produced. Occasionally a double fruit is produced, not by the incorporation of two flowers, but by the abnormal development of a second carpel in the flower.
Arrangement of Fruits.
A. True fruits—developed from the ovary alone.
1. Pericarp not fleshy or fibrous.
i. Indehiscent—not opening to allow the escape of the seeds—generally one-seeded. Achene; caryopsis; cypsela; nut; schizocarp.
ii. Dehiscent—the pericarp splits to allow the escape of the seeds—generally many-seeded. Follicle; legume; siliqua; capsule.
2. Pericarp generally differentiated into distinct layers, one of which is succulent or fibrous. Drupe; berry.