INDEHISCENT APOCAEPOUS FRUITS. 311 



given to fruits which differ from the achsenium in being composed of 

 more than one carpel. When the pericarp is extended in the form of 

 a winged appendage, a samara (samera, seed of Elm) or swmaroid 

 actuenium is produced, as in the Ash (fig.- 533, p. 299), common Sycamore 

 (fig. 561), and Hiraea (fig. 562). In these cases there are usually 

 two achsenia united, one of which, however, as in Fraxinus oxyphylla 

 (fig. 533), may be abortive. The Wing (fig. 561 a) is formed by the 

 carpel, and is either dorsal, i.e. a prolongation from the median vein 

 (fig. 561 a), or marginal, that is, formed by the lateral veins (fig. 

 562 a). It surrounds the fruit longitudinally in the Elm. When 

 the pericarp becomes so incorporated with the seed as to be inseparable 

 from it, as in grains of Wheat, Maize, Eye (fig. 563), and other 

 grasses, then the name caryopsis (xA^vov, a nut, and o'^ig, appearance) 

 is given. 



There are some fruits which consist of two or more achsenia, at 

 first ' united together, but which separate when ripe. Of this nature 

 is the fruit of the Tropseolum or Indian Cress, also that of Labiatee 

 and Boraginacese, which is formed of four achsenia attached to the 

 axis (fig. 436, p. 247), whence the common style appears to proceed. 

 Some of these are occasionally abortive. In the ripe state the 

 pericarp separates from the seed in these cases ; and thus there is a 

 transition from indehiscent achsenia to single-seeded dehiscent peri- 

 carps. The cremocarp (x^ifidu, I harig), or the fruit of Umbel- 

 liferse (fig. 550, p. 306), is composed of two achsenia united by a com- 

 missure to a common axis or carpophore (x.ag'jrog, fruit, and <pogiia, I 

 bear), from which they are suspended at maturity. It is sometimes 

 denominated diachmnium (dig, twice), from the union of two achsenia, 

 which in this instance receive the name of mericarps (/^egos, part), or 

 hemicarps {rfuevg, half, and x.ag'Trog, fruit). 



The Nut or Olans.- — This is a one-celled fruit with a hardened 

 pericarp, surrounded by bracts at ^the base, and, when mature, con- 

 taining only one seed. In the young state the ovary contains two or 

 more ovules, but only one comes to maturity. It is illustrated by the 

 fruit of the Hazel and Chestnut, which are covered by leafy appendages, 

 in the form of a hush, and by the Acorn, in -tvhich the leaves or bracts 

 are united so as to form a cupula or cup (fig. 281, p. 191). The parts 

 of the pericarp of the Nut are united so as to appear one. In Sagus, 

 or the Sago Palm, the nut is covered by peculiar tesselated epicarp, 

 giving the appearance of a cone. 



The Drupe (drupm, unripe olives). — This is a succulent fruit 

 covered by a pericarp, consisting of epicarp, mesocarp, and endocarp ; 

 and when mature containing a single seed. This term is applied to 

 such fruits as the Cherry, Peach, Plum, Apricot, Mango, Walnut, 

 Nutmeg, and Date. The endocarp is usually hard, forming the stone 

 of the fruit, which encloses the . kernel or seed. The mesocarp is 



