Classification of plant fruits

Fruit can be divided into fleshy fruit and dried fruit according to the texture of peel. The skin of fleshy fruit is soft, juicy and usually brightly colored, which can attract animals to eat and spread seeds. Seeds often have hard structures or acid-resistant chemicals, which can protect seeds from being corroded by digestive juice when passing through the digestive tract of animals. Many delicious fruits we eat belong to fleshy fruits.

When the dried fruit is ripe, the peel is dry and hard, and the boundaries between endocarp, mesocarp and exocarp are not obvious. Without sweet juice and attractive color, dried fruits still have their own unique skills in seed transmission. The achene of Showa grass has white crown hair, which is easily blown in all directions by the wind. The samara of maple is like a small flag, which is also blown away by the wind; Lanzhou lily seeds. When the pod breaks, the yellow substance is ejected by the twisting force; The fruits brought by Bidens bipinnata and sheep have hooks and thorns, which can be attached to people's clothes or animal's fur and migrate with them.

Other appendages of some plant flowers will also be accompanied by some developing fruits. For example, the bright red and lovely strawberry is formed by the expansion of the receptacle, and the sesame-like particles on the surface of the strawberry are its real achenes; The fleshy part of fig is developed from floral axis. Pineapple is formed by the whole inflorescence * * * *; The perianth and receptacle of apple also expand, enrich, heal and develop with the growth of ovary wall. Academically, these fruits developed from structures other than ovaries are called fake fruits, and the corresponding real fruits refer to fruits developed purely from ovaries.

Single fruit: the fruit formed by one or more pistils in a flower.

Aggregate fruit: A fruit formed by the coexistence of most free pistils and receptacle in a flower.

Development and characteristics of fruits

During the fruit development, great changes have taken place in all parts of the flower. Calyx and corolla generally fall off, and the styles of stigma, stamen and pistil also fall off and wither. At this time, the ovule develops into a seed, the ovary gradually increases, and the fruits are numerous. A fruit developed from an ovary is called a true fruit. Such as peaches, oranges, apricots and persimmons. In some plants, besides the ovary, other parts of flowers, such as perianth, style and inflorescence axis, also participate in the formation of false fruits, which are called false fruits. Such as pears, mountain ballast, figs, wind pears, etc.

Fruit formation requires pollination and fertilization, but some plants do not need fertilization, and only after pollination can they develop fruit. This kind of fruit is seedless and called parthenocarpy, such as bananas, seedless grapes and seedless oranges. Some plants are artificially induced to form seedless fruits with edible value. This kind of fruiting is called induced parthenocarpy. For example, the pollen of potato stimulates the stigma of tomato and forms seedless tomato. Seedless fruit is not necessarily formed by parthenocarpy, but also by ovule development being blocked after fertilization, thus forming seedless fruit.

There are often cuticles, wax skins, hairs, thorns, nodules, wings and other appendages on the outside of fruits. If the exocarp of peach is hairy; Persimmon skin is coated with wax; Bidens bipinnata and Datura stramonium have thorns on their fruits; Litchi fruit has tumor process; The fruits of elms and mechanical trees have wings.

1 fleshy fruit: The pericarp is fleshy when the fruit is ripe.

Berry: The exocarp is thin, and the mesocarp and endocarp are juicy (tomatoes, grapes).

Drupe: The exocarp is thin, the mesocarp is fleshy and the endocarp is hard (peach, plum and apricot).

Citrus fruits: exocarp leathery, mesocarp loose, endocarp membranous, and saccate (orange, orange).

Pear fruit: fake fruit, fleshy exocarp and mesocarp, and papery or leathery endocarp (apples and pears).

Zanthoxylum bungeanum: False fruit, hard exocarp, fleshy mesocarp and endocarp, well-developed placenta (melon).

2. Dried fruit: When the fruit is ripe, the peel is dry.

When the fruit is ripe, the peel is cracked.

Pod: one heart, one skin and one cavity, which cracks at the same time along the back seam and abdominal seam when mature.

Hair follicle: one heart and one skin, cracking along the back or abdomen suture when mature. (magnolia)

Pod: two carpels, with false double cavities and false septa, which crack along the abdominal seam when mature.

Capsule: One or more carpels with multiple dehiscences. (cotton)

B fruit closure: when the fruit is ripe, the peel is dry but not cracked.

Achene: The pericarp and seed coat are separated and contain a seed. (Sunflower, Buckwheat)

Dianthus caryophyllus: The peel and seed coat can't be separated when they heal, and it contains a seed.

Samara: The pericarp extends into a wing shape. (elm, Ailanthus altissima)

Nut: The peel is harder than achene and contains seeds. (chestnuts, hazelnuts)

Fruit dehiscence: it is developed from a compound pistil with two or more carpels, each containing a seed, and the fruits are separated from each other along the central axis when they are ripe. (mallow, hollyhock)

Double hanging fruit: two carpels, separated along the central axis when mature, double hanging in the air. (carrot)