Elementary botany . Fig. 472. Seed, or akene, of buttercup. 869. The akene.—The thin dry wall of the ovary enclosesthe single seed. It usually does not open and free the seedwithin. Such a fruit is an akene. An akene is a dry, indehiscent fruit. All of the crowded butseparate pistils in the buttercup flower when ripemake a head of akenes, which form the fruit ofthe buttercup. Other examples of akenes arefound in other members of the buttercup family,also in the composites, etc. The sunflower seedis a good example of an akene. 870. The samara.—The winged fruits of the maple (fig. 574),elm, etc.
Elementary botany . Fig. 472. Seed, or akene, of buttercup. 869. The akene.—The thin dry wall of the ovary enclosesthe single seed. It usually does not open and free the seedwithin. Such a fruit is an akene. An akene is a dry, indehiscent fruit. All of the crowded butseparate pistils in the buttercup flower when ripemake a head of akenes, which form the fruit ofthe buttercup. Other examples of akenes arefound in other members of the buttercup family,also in the composites, etc. The sunflower seedis a good example of an akene. 870. The samara.—The winged fruits of the maple (fig. 574),elm, etc., are indehiscent fruits. They are sometimes called key fruits. 871. The caryopsis is a dryfruit in which the seed is con-solidated with the wall of theovary, as in the wheat, corn,and other grasses. 872. The schizocarp is a dry fruit consisting of severallocules (from a syncarponsgyncecium). At maturity the. Fig. of red oak. An acorn. carpels separate from each other, but do not themselves dehisceand free the seed, as in the carrot family, mallow family. 873. The acorn.—The acorn fruit consists of the acorn andthe cup at the base in which the acorn sits. The cup is acurious structure, and is supposed to be composed of an involucreof numerous small leaves at the base of the pistillate flower,which become consolidated into a hard cup-shaped body. Whenthe acorn is ripe it easily separates from the cup, but the hardpericarp forming the shell of the acorn remains closed. Frostmay cause it to crack, but very often the pericarp is split open atthe smaller end by wedge-like pressure exerted by the emergingradicle during germination. 452 RELATION TO ENVIRONMENT, 874. The hazelnut, chestnut, and beechnut.—In these fruits acrown of leaves (involucre) at the base of the flower grows around
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