Anatomy of Stone and Seed
Professor:
Student:
Beograd, 2012
1
and germination strategies. The classification of the fruits may be based on the
consistence of the pericarp as to whether it is dry and hard, or soft and fleshy. Fruits may
also be classified on the basis whether they dehisce or not when ripe and whether they are
single-seeded or multiple-seeded. In single-seeded indehiscent fruits, the unit of
dissemination is fruit itself rather than seed.
1. Anatomy of stone fruits
A fleshy fruit, such as a peach, plum, or cherry, usually having a single hard stone
that encloses a seed. A stone-fruit; a fruit in which the outer part of the pericarp becomes
fleshy or softens like a berry, while the inner hardens like a nut, forming a stone with a
kernel, as the plum, cherry, apricot, and peach. The stone inclosing the kernel is called
the putamen (or endocarp), while the pulpy or more succulent part is called the sarcocarp
(or mesocarp), and the outer covering the epi-carp.
These are a fruits with four major parts: a thin skin, a fleshy body, a hard stone,
and an inner seed. Many are also edible, with people eating the various parts, depending
on which kind it is. A surprising number of foods are considered stone fruits or drupes,
ranging from almonds to peaches. Most cultures eat several different varieties, some of
which play a major culinary role. They can generally be farmed or cultivated, although it
is also possible to collect wild versions. (Cutler, Botha, Stevenson, 2007)
Working from the outside in, the first layer of a stone fruits is a thin skin or
exocarp that protects it from the elements. Next comes the mesocarp, a thick layer of
fleshy material that is often made juicy and sweet to appeal to animals, so that animals
will eat the fruit and then spread the seeds in their feces. Next comes the stone or
endocarp, which is extremely hard to protect the delicate seed inside. When the seed
lands in good growing conditions, it will sprout, cracking the endocarp.
4
The fruit wall is termed the pericarp and it is divided in to three regions, outers or
exocarp, the middle or mesocarp, and inner or endocarp. Anatomy of pericarp of fleshy
fruits is histological rather uniform, with any given fleshy fruits, the anatomy of stone
fruits, that is those with sclerified internal layers such as in peach and mango, shows
histological differentiation, usually in the endocarp. The sclerified tissue of the endocarp
can have different orifins in the different fruit. Some fruits have the endocarp derived
from the inner epidermis, and in other cases from a multilayered epidermis derived from
periclinal divisions in the epidermis.
Still other fruits have the sclerified tissue derived from hypodermis, or in other
cases from a multiple hypodermis derived from the periclinal divisions of hypodermis.
Two other patterns of the development of stony endocarp are those derived from the
epidermis plus multilayered hypodermis, and those with the stony endocarp derived from
both multiple epidermis and a multiple hypodermis. Although these patterns are know to
occur, there is a paucity of data concerning their occurrence within the flowering plants,
and this is an area desperately in need of comparative studies.
In families like the
Apiaceae
,
Asteraceae
and
Lamiaceae
for example fruit
anatomy provides many useful diagnostics and taxonomic caracters. Undoubtedly, as
more families are systematically studied, much of taxonomic and perhaps phylogenetic
importance will emerge.
Many species have been studied for fruit and seed structure, relatively few
families have been carefully studied systematically and in detail, followed by
documentation of the results. The wide use of seed and fruits in human food and animal
feedstuffs has made knowledge of their anatomy of paramount importance. ( Roth, 1977).
1.1 Morphology of the fruit and seed of
Prunus persica
Prunus persica
, is a deciduous tree, native to China and South Asia, where it was
first cultivated. It bears an edible juicy fruit also called a peach. The species name
persica
5
The stony (
i.e.
composed of sclereids) endocarp encloses a single seed. The
extensive mesocarp is fleshy and is covered by a thin skin (exocarp) comprised of
epidermis and collenchyma.
The fruit development is strictly connected to embryogenesis in peach, moreover,
in this specie, seed development is also necessary for fruit set. In the seed, development is
characterized by a fast growth of endosperm that starts immediately after fertilization
concurrently with the nucellus re-absorption, and lasts until the beginning of endocarp
lignification, when the seed reaches its final size. At the end of pit hardening, seed
volume is mainly made up of endosperm and the embryo is at the heart stage. Thereafter,
embryo growth resumes and cotyledon development is paralleled by the endosperm re-
absorption.
Seed maturation is characterized by lipid accumulation (Ognjanov et al. 1995)
synthesis of specific late embryogenesis abundant (LEA) proteins and dehydration. Seed
abnormalities at the early stages of development bring about abortion and fruitlet
abscission (Stutte and Gage, 1990). Seed presence is always necessary to achieve normal
fruit development even though embryo development is incomplete.
1.2 Ovary
Fertilization of the egg by the male nucleus (forming the zygote) must occur to
stimulate fruit development in
Prunus.
The five petals, usually pink but occasionally white, five sepals, and three whorls
of stamens are borne on the outer rim of the short tube that forms the base of the flower.
The pistil consists of a single carpel with a relatively long style and an enlarged basal
portion, the ovary, which becomes the fruit. The peach develops from a single ovary that
ripens into a fleshy, juicy exterior, making up the edible part of the fruit, and a hard
interior, called the stone or pit. Of the two ovules in the ovary, usually only one becomes
7
