Botany: Anemofilia of flowers
The anemofilia is typical of species populations that are monospecific dense vegetation or pauciespecíficas (with one or a few species), where are the dominant species of the ecosystem . Only thus can be effective wind pollination.The plants growing scattered, lost between feet of other species, are usually pollinated by insects or other animals iszoophilic , because they require specialized vectors able to find on a few individuals existing in a given area.Anemophilous species instead have to produce very large amounts of pollen, which is sometimes very noticeable in forests of pine , when the soil is stained yellow by the large number of these species produce pollen during flowering.Only when these conditions exist can ensure pollination.
Among the trees the condition is typical of anemophilous conifers , which tend to form monospecific forests in colder latitudes and mountains, or the dominant trees in the forests of the latitudes warm, such as oak or beech . The anemofilia not found in forest trees species-rich regions characteristic of tropical . The anemofilia is also characteristic of the grasses and other plants nearby (such as Cyperaceae ), which are open grassy where the wind is no obstacle.
Other wind-pollinated group is the family Juglandaceae , constituted by the genera Juglans , which includes Walnut species and Carya and Pterocarya , among which is the so called Winged Nut.
The anemofilia involves a lot of adaptations at the level of inflorescences , flowers and gametophytes. Thus, anemophilous species often have showy little flowers without petals attractive or, directly, without any petals, as in the ash ). This disappearance of the perianth also applies to other structures such as fairly typical nectaries , odoróforos and nectar guides , which will become unnecessary in these species. In addition, the flowers are arranged in inflorescences often pendulous (eg in the catkins of male pendulums Corylus , Alnus and Quercus ).
Also, anemophilous species deciduous tend to flourish early, before the foliage appears, so that it does not slow down the movement of pollen (eg, in the oak , alder , ash , willows , poplars and elms ).
This particular mode of pollination requires that the pollen is small or a surface / volume ratio very high, reducing its rate of sedimentation and facilitates further when it gets blown away. Thus, for example, composed of the genus Artemisia pollen have a small, smooth and dry, while the majority of the members of the family have larger, ornate and covered in oil, which facilitates the aggregation and adhesion to vectors animals. In the pines the lightness is achieved through two air sacshollow, reducing its density and surface friction increases. Furthermore, the pollen grains of anemophilous species lack pollen cement are dry and smooth exine frequently, so easily separated from each other.
The production of large amounts of pollen in these species is achieved by increasing the number of male flowers or stamens (eg Corylus , there are 2 ½ million pollen grains per stamen). Pollen removal is facilitated by the mobility of the filaments of the stamens ( Poaceae ) or tension mechanisms anthers inside the flower bud that determine literally the "explosion" of the flower and the concomitant release of a cloud of pollen the time of anthesis ( Urtica , Pilea ).
The styles and stigmas of anemophilous species are greatly enlarged in order to facilitate the capture of pollen that is carried in the air. The number of eggs in the carpels , however, is usually very small compared to the fact that pollination is carried out usually pollen grains isolated.
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