ANGIOSPERMS. 



427 



(monocarpellary) ovaries in a flower, or, which is the same thinj,^, if the flower is poly- 

 carpous ; in this case the mature gynaeceum forms an aggfegti/e fruit, for wliich the term 

 syncarp would be preferable. Thus the small fruits of a flower of Rimunculus or 

 Clematis and the larger ones of Paeotiia and Helleborus form together an aggregate 

 fruit ; the blackberry is a similar structure, being formed of a number of plum-like fruits 

 from one flower; in like manner the pulpy 

 torus of the hip encloses an aggregate fruit, 

 but the enclosed fruits are dry, not pulpy. 

 The aggregate fruit must not be confounded 

 with the pseudocarp formed from an inflores- 

 cence, like the mulberry and fig already 

 described, or the pine-apple or that of 

 Benthamia fragifera. 



The single plurilocular ovary of a flower 

 may develope in such a manner as to produce 

 two or more parts each containing a seed, 

 and appearing to be a separate fruit ; each of 

 these may be called a inericiu-p or partial fruit, 

 and the whole fruit is a schizocarp. This 

 separation may commence at an early stage, 

 as in Tropaeolum, in which each loculus with 

 one seed rounds itself off and finally separates 

 from the rest as a closed mericarp, and in 

 the Boragineae and Labiatae, in which each 

 of the two carpels forms two one-seeded 

 projections, which finally separate into four 

 distinct mericarps surrounding the style and 

 known as cocci. Sometimes the separation 

 is caused by the splitting and rending of 

 certain layers of tissue in the ripe fruit, as in 

 the Umbeliiferae and in Acer, where the fruit 

 by longitudinal division of the dissepiment 

 separates into one-seeded halves (mericarps) ; 

 the quinquelocular fruit of Genmium splits 

 in the same manner into five one-seeded 

 mericarps. 



True single fruits are generally unilocular 

 or plurilocular according to the structure of 

 the ovary ; but the unilocular ovary may 

 become a plurilocular fruit owing to the 

 presence of spurious dissepiments, that is, 

 such as cannot be considered as the inflexed 

 margins of the carpels ; the loculi thus formed 

 may lie above or beside one another ; in the 

 lomentmn of some Leguminosae, Cassia fistula for instance, they lie one above the 

 other, in the legume oi Astragalus beside each other. The plurilocular ovary may on 

 the contrary produce an unilocular fruit by the suppression of one or more loculi, as in 

 the oak and lime. Fruits therefore cannot, like ovaries, be divided into monomerous 

 and polymerous, these terms having now a different meaning. 



The wall of the ovary developes into the wall of the fruit or pericarp. If the pericarp 

 is sufficiently thick it can generally be distinguished into two or three layers of tissue of 

 different structure ; the outer layer (often only an epidermis) is then called the epicarp, 

 and the inner the cndocarp ; if there is still a third layer between tiiese, it is termed the 

 niesocarp, and if it is fleshy (pulpy) the sarcocarp. 



I-'IG. 354. Zygoniorplious flower of Orchis maciilala. A 

 bud divided syminetrically through the middle. /.' transvers 

 section of the bud. C transverse section of the ovary. D 

 entire flower fully developed after removal of a lateral leaf of 

 the perianth. The letter x denotes the mother-axis of the 

 flower, * the bract, j the outer, p the inner perianth-leaves, 

 the posterior one of which becomes the labelluni I, a the 

 single anther, st staminodes, gs gynostenium, // pollmiuni. h 

 its viscid disk, sp the spur of the labelluni, y the inferior ovary 

 which is twisted in D. 



