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About 350,000 plant species are currently known. Of this total, over 250,000 are angiosperms.
The word angiosperm comes from Greek. angels, which means 'purse', and sperma, 'seed'. These plants represent the most varied group of species among the components of the kingdom Plantae or Metaphyta.
Main features of angiosperms
Arborescent angiosperms have three main components: roots, trunk and sheets.
- At roots They are the fixative organs of the tree to the soil and absorb water and mineral salts, indispensable for the survival of the plant.
- O trunk, consisting of numerous branches, is the aerial organ responsible for the formation of leaves, also making their connection with the roots.
- And the sheets They are the organs where photosynthesis will occur, that is, the process in which the organic compounds essential for the maintenance of plant life are produced.
Each flower, which appears periodically in the branches, is a reproduction system and is formed by the gathering of modified leaves attached to the floral receptacle, which is shaped like a flat disk. In turn, the floral receptacle is at the top of the floral peduncle, which is the "head" of the flower. In the receptacle there are a series of concentric circles in which the floral pieces are inserted. From the outside, there are four types of modified leaves constituting the flower: sepals, petals, stamens and carpels.
At sepals they are the most external, usually green, and have the protection function of the flower bud, at which stage the flower has not yet opened. The set of sepals is called the Cup. The petals come next. They are white or colored and form the corolla (name derived from crown), with the purpose of attracting the so-called pollinating agents, often insects. The food these insects are looking for is a sugary solution, the nectar, produced by glands generally existing at the base of the petals.
The stamens they are disposed more internally in the receptacle. Each stamen has the appearance of a toothpick, with a stem, the fillet, supporting a dilated portion, the anther. The set of stamens forms the androceu, considered the male component of the flower. In the anther are produced pollen grains.
O carpel occupies the center of the floral receptacle. It is long, with a slight dilation at its apex, the stigma continuing with a short stiletto, following the ovary. Inside the ovary, there are the eggs. The solitary carpel is a component of gyno, the feminine part of the flower.
Flowers are classified according to various criteria. Let's look at some of them.
1- As for the number of external whorls
- Aclamids: without chalice and without corolla. Example: Grasses.
- Monoclamide: have chalice or corolla.
- Diclamids: when they have a chalice and corolla.
- Different chalice and corolla: Perianto, typical of dicotyledons. Ex .: rose
- Equal chalice and corolla (tepals): Perigone, typical of monocotyledons. Ex. Lily
2- Regarding the sex of flowers
- Monoclines or Hermaphrodites: have both sexes, androceu and gynoecium. Ex .: cloves, orange.
- Dicline or Unisex: has only androceu or gyno. Eg pumpkin, papaya.
- Sterile: they do not have androceu or gynoecium, or present themselves but are not fertile. Eg daisy.
- Monoic vegetables: have monocline or dicline flowers.
- Dioic vegetables: present dicline flowers.
3- Regarding the number of pieces per whorl
- Cameras: three or multiple of three pieces. Ex .: Monocotyledons.
- Cameras, Cameras, Cameras: two, four, five pieces, respectively, by whorl. Ex .: Dicotyledons.
4- Regarding the pollinating agent
- Ornithophil - pollinated by birds
- Anemophila - wind pollinated
- Chiropterophil - pollinated by bats
- Entomophilous - pollinated by insects
- Anthropophile - pollinated by man