THE ANGIOSPERMAE 1529 



fruits, popularly called " nuts ", e.g., Walnut, Almond, Coconut, are the 

 endocarps of fleshy fruits (see below), enclosing single seeds. 



The name Carceridus has also been applied to indehiscent fruits formed 

 from a superior, pluricarpellary ovary and containing one or more seeds. 

 It is not entirely distinguishable from the term nut, but can be applied to 

 some of the Cruciferae in which the fruit does not dehisce, e.g., Bunias and 

 Crambe, and to some rare types of indehiscent capsules. 



True akenes may sometimes be enclosed by external structures without 

 thereby falling into the category of false fruits. For example, in the 

 Nyctaginaceae the akenes are enclosed by the indurated base of the perianth, 

 and in Carex the akene is enclosed in a sac, called the utriculus or peri- 

 gynium, which is an undivided, sheathing bracteole. 



While the akene may be regarded as the simplest type of fruit and the 

 one in which usually the amount of alteration of the tissues during ripening 

 is least, there are signs that in some cases its simplicity is not primary but 

 secondary and that it has been reduced from a many-seeded type of fruit. 

 Abortive or vestigial ovules persist in some cases, notably in Anemone, 

 either with or without vascular supply bundles. Among Rosaceae and 

 Ranunculaceae a series of forms may be selected which illustrate the 

 possibility of reduction leading from a multiovulate, three-trace carpel, 

 to a uniovulate, single-trace carpel; the greatest degree of reduction being 

 shown by Ranunculus. Reference back to what we have previously said 

 about peltate and semi-peltate carpels (see p. 121 5) will show that there are, 

 however, reasons for thinking that some uniovulate carpels with median 

 ovules belong to a difi^erent development pattern from the multiovulate 

 types with marginal placentation and are primitively uniovulate. 



2. Schizocarpic Fruits. These are products of plurilocular ovaries 

 which at maturity separate into their component carpels, each 

 of which is an akene, indehiscent and one-seeded. The com- 

 ponent parts are called mericarps, or sometimes cocci. True 

 schizocarps are found in the Umbelliferae and in some of the 

 Malvaceae {Malvo, Lavatera) (Fig. 1392). As the former are 

 from inferior and the latter from superior ovaries, they provide 

 another instance of the illogical nature of the separation of "false" 

 fruits. In Umbelliferae the fruit is called a cremocarp (Fig. 1393). 

 It is bicarpellary and the two carpels, after separation, remain for 

 some time suspended from a forked prolongation of the floral 

 axis called the carpophore. The bicarpellary fruits of Acer are 

 also cremocarps, each mericarp being a winged samara. In the 

 Labiatae (Lamiaceae) the ovary is also bicarpellary, but at 

 maturity the carpels separate into four one-seeded units, with 

 hard walls, which are called nutlets (nuculi or cocci), each of the 

 carpels being subdivided by a false septum which develops 

 secondarily from the true septum. 



The schizocarps provide a hnk between indehiscent and dehiscent fruits, 



