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Fruits arise from fertilized flowers. The ovary wall, called the pericarp, of a flower is made of three layers: the exocarp, mesocarp, and endocarp; these layers develop to become the exterior skin, fleshy area beneath the skin, and internal area in which seeds can be found, respectively, of a fruit. The endocarp is the inner area of the fruit in which the seeds are contained; ovule chambers of flowers from the endocarp in fruits. The seeds of a fruit are typically toward the center of the fruit and are mature ovules from the flower’s ovary. The remains of the sepals and stem can be seen on some fruits.
Plants have multiple benefits from fruits. Having fruits allows embryo dispersal far enough away from the parent as to reduce competition for resources, thus also allowing angiosperms to colonize large areas.
Fruits also allow plants various ways of dispersing their seeds. These dispersal methods include fleshy fruits, which are dispersed by animals, that have seeds with adapted hard coats to protect the embryo from stomach acids and digestive enzymes. Certain types of fruits have hooked spines and stick to mammals’ fur or clothing, thus being dispersed wherever the mammal travels when the fruits lose grip of the fur/clothing and fall off. Some fruits have adapted wing-like structures that aid in distribution by wind when those fruits are blown away from the parent plant. Some fruits are dispersed via floating in water.
There are five main types of simple fruits. Drupes form their skin, fleshy area, and protective seed coating from the ovary wall of a flower with only one ovary and one chamber (example: peach). Pods form from flowers with one ovary and one carpel chamber; the flowers from which pods develop have many ovaries in a single row in the carpel chamber and its seeds are attached to the placenta on one side of the ovary (example: string bean). Achenes are hard protective fruits that develop from flowers with a single-chambered ovary, whose wall becomes hard and protective (example: sunflower seed). Pomes develop from flowers with one multi-chambered ovary. The seeds of pomes are separated in carpel chambers and are attached to the placenta at the center of the fruit, and the fleshy part of pomes develop from the petals, sepals, etc. (example: apple). Berries form from flowers with a singe multi-chambered carpels and a single ovary. Carpel chambers form the segments in which seeds are housed; the seeds are attached to the placenta at the center of the berry (example: tomato).
Aggregate fruits develop from a multi-ovary flower, in which each ovary has one ovule, matures into a section of the fruit, and is attached to the central stem (example: strawberry).
Double fertilization in an angiosperm plant is the process by which a zygote and triploid endosperm are created. One sperm nucleus fuses with the eg nucleus, thus producing a zygote. The other sperm nucleus fuses with the polar nuclei, thus producing a triploid endosperm that serves as nutrients and feeds the developing embryo.
The dicotyledonous root contains many structures. In a longitudinal section, the root cap is at the tip of the root and serves to protect the growing root and the layer of meristematic tissue under it. Underneath the root cap is the apical meristem, which gives rise to undifferentiated cells. The zone of cell division is after the apical meristem and includes procambium tissue. The zone of elongation is the area where cells mature and lengthen, thus pushing the root into the soil. The zone of maturation is after that of cell division and elongation; the maturation zone has vascular tissue in its center and root hairs extending from individual epidermis cells, which increases surface area for nutrient absorption. From the zone of cell division up to the zone of maturation there is ground tissue between the epidermis and endodermis.
The cross section of a dicot root has xylem for water transport arranged in star shape in the middle, surrounded by phloem, which transports sugars, with a ring of pericycle and endodermis surrounding the vascular tissue. A layer of cortex lies between the endodermis and the exodermis.
In a monocot root cross section, ground tissue forms a pith in the center of the section, with xylem and phloem in respective rings around the pith. Just as in the dicot root cross section, that of the monocot root also has a ring of pericycle and endodermis, respectively, encompassing the vascular tissue, and a layer of cortex between the endodermis and exodermis.
The typical angiosperm flower has four whorls, circles of sets of organs organized in a circle around the receptacle (the part that connects the flower to the stem). The first and outermost whorl is called the calyx and consists of the sepals, which are usually green. The second whorl, called the corolla, consists of the petals, which are modified leaves and are usually colourful and attract pollinators. The third whorl, the androecium, consists of the stamens, which are the filaments with stamen made of pollen sacs filled with pollen grain at the tips. The fourth whorl is one or more carpels, which consist of a style with a stigma at the end, connecting to the ovary at the base of the flower. Inside of the ovary are the ovules, which, when fertilized and reach maturity, become seeds in the fruit which will develop from other parts of the flower.
Note: the gametophte is the large butterfly-shaped structure, and the sporophyte is the small heart-shaped structure growing from the notch of the gametophte on the right.