What Is A Stone Or Pome Fruit

In the case of cherry (typical of stone fruit, such as peach, plum, or apricot), the fruit develops only from the ovary of a single flower (Figure F3.1). No other floral or nonfloral tissue contributes to mature fruit structure. The floral organs surrounding the ovary are free from the ovary and are attached to the floral stalk, or receptacle, below the ovary. The ovary is thus "superior" to such parts. The bases of the flower's sepals, petals, and stamens form a floral cup, or hypanthium, which surrounds the central female structure, or pistil. The ripened ovary of stone fruit typically contains only one large seed, from only one of the flower's two original ovules. The mature ovary wall surrounds the seed,

CHERRY

Ovarian Region Fruit

Ovarian Region Fruit

APPLE

Ovarian Region

APPLE

Ovarian Region

FIGURE F3.1. Fate of floral tissues in development in a stone fruit (cherry) and pome fruit (apple). The wall of the superior ovary in the flower of cherry develops into the three regions of the mature fruit's pericarp, with the innermost layer becoming the lignified pit region. The receptacle and hypanthium contribute no tissue to the fruit. In apple, extra-carpellary floral tissues provide most of the edible flesh that surrounds the five seed locules in the inferior ovary. These nonovarian tissues embed the ovary wall (leathery endocarp) deep within the core of the apple. Both receptacle and hypanthium regions of the flower contribute to the mature fruit flesh.

composes the flesh and hard pit, and is called the pericarp. The pit is the lignified inner pericarp, the endocarp. Most of the juicy fruit flesh is derived from the middle ovary wall, or mesocarp, and the skin, from the outer ovary wall, or exocarp.

In the case of apple (typical of pome fruit, such as pear and quince), the identification of the origin of fruit tissues is less obvious. The ovary region of the apple flower consists of both the ovary itself and surrounding adherent portions of the flower. Some view those surrounding tissues as portions of the flower's floral cup (hypan-thium); others see those tissues as taking origin from the stem supporting the flower, the receptacle. It is from this latter interpretation that we often apply the stem terms "cortex" and "pith" to the outer and inner fleshy regions of the mature fruit. Regardless, the ovary and surrounding tissues are situated below the floral cup and the five free stigmas surmounting the ovary. Pome fruit thus have an "inferior" ovary. As the fruit grows, the apple flesh is derived to a great extent from the nonovarian tissues surrounding the embedded ovary. The ovary proper develops as the cartilaginous inner tissue (endocarp) at the fruit's core. The main flesh of the fruit is derived from the inner (pith) and outer (cortex) tissues that surround the ovary and its ovules (seeds). The hypanthium just above the inferior ovary of the flower will enlarge to varying degrees, to contribute flesh to the fruit's terminal lobes.

0 0

Post a comment