488 



HUTCHINSON'S POPULAR BOTANY 



FIG. 606. DOUBLE COCO-NUT 



(Lodoicea seychellarum). 



A drupe. 



with a hard outer layer, but it is more 

 often called a pepo (fig. 611). Dispersion 

 of the seeds of berries is effected largely 

 by animals, under circumstances very 

 similar to those attending the seed dis- 

 persal of drupaceous fruits. The seed- 

 coats resist the action of digestive juices 

 as effectually as does the stony endocarp 

 of the plum or cherry. 



Few indehiscent fruits are more puz- 

 zling on a first examination than the 

 orange. The development of the three layers of the pericarp is very 

 remarkable, and forms one of the characteristics of a remarkable kind of 

 fruit the hespemdium (fig. 612). The peel of the orange 

 consists of epicarp and mesocarp ; while the membranous 

 partitions which project internally towards the centre of 

 the fruit, and divide off the juicy pulp into separate groups 

 of cells (the misnamed " quarters " of the orange) consist 

 of endocarp. The pulp itself, in which the " pips " or 

 seeds are embedded, is a development of succulent cells 

 (internal hairs) from the inner lining of the ovary i.e., 

 from the endocarp. The lemon, shaddock, etc., have the 

 same distinguishing feature, and are equally good examples 

 of the hesperidium. 



The three sorts of indehiscent fruits which we have been 



considering drupe, berry, 

 and hesperidium are all 

 succulent ; the others are 

 dry. They are the achene, 

 nut, caryopsis, and cypsela. 



A dry indehiscent fruit developed from 

 a pistil with single carpel is an achene ; if 

 the pericarp is thin and leathery, and not 

 adherent to the seed-coat, it is an achene-; 

 if hard and woody, a nut. Any dry one- 

 seeded indehiscent fruit with a hard endo- 

 carp is called a nut. As a rule, a nut has 

 but one chamber, the partition-walls dis- 

 appearing by atrophy as the fruit develops. 

 The fruits of the Buttercups (fig. 613) are 

 achenes ; the fruits of the Hazel (Corylus, 

 fig. 614) are nuts. The husk which partly 

 envelops the hazel-nut is formed by greatly 

 enlarged bracts. 



FIG. 607. SEC- 

 TION THROUGH 



THE " STONE " 

 OF A PLUM. 



FIG. 608. SECTION THROUGH A PLUM. 



Showing the "stone" invested by the 

 fleshy mesocarp. 



