AskDefine | Define anther

Dictionary Definition

anther n : the part of the stamen that contains pollen; usually borne on a stalk

User Contributed Dictionary

English

Noun

anther
  1. The pollen-bearing part of the stamen of a flower.

Translations

Extensive Definition

The stamen (plural stamina or stamens, from Latin stamen meaning "thread of the warp") is the male organ of a flower. Each stamen generally has a stalk called the filament (from Latin filum, meaning "thread"), and, on top of the filament, an anther (from Ancient Greek anthera, feminine of antheros "flowery," from anthos "flower"), and pollen sacs, called microsporangia. The development of the microsporangia and the contained haploid gametophytes, (called pollen-grains) is closely comparable with that of the microsporangia in gymnosperms or heterosporous ferns. The pollen is set free by the opening (dehiscence) of the anther, generally by means of longitudinal slits, but sometimes by pores, as in the heath family (Ericaceae), or by valves, as in the barberry family (Berberidaceae). It is then dropped, or carried by some external agent — wind, water or some member of the animal kingdom — onto the receptive surface of the carpel of the same or another flower, which is thus pollinated. Typical flowers have six stamens inside a perianth (the petals and sepals together), arranged in a whorl around the carpel (pistil). But in some species there are many more than six present in a flower (see, for example, the spider tree flower, below). Collectively, the stamens are called an androecium (from Greek andros oikia: man's house). They are positioned just below the gynoecium. The anthers are bilocular, i.e. they have two locules. Each locule contains a microsporangium. The tissue between the locules and the cells is called the connective.
In an immature, unopened flower bud, the filaments are still short. Their function is then to transport nutrients to the developing pollen. They start to lengthen once the bud opens. The anther can be attached to the filament in two ways:
  • basifixed : attached at its base to the filament; this gives rise to a longitudinal dehiscence (opening along its length to release pollen)
  • versatile : attached at its center to the filament; pollen is then released through pores (poricidal dehiscence).
Stamens can be connate (fused or joined in the same whorl):
  • monadelphous : fused into a single, compound structure
  • diadelphous : joined partially into two androecial structures
  • synantherous : only the anthers are connate (such as in the Asteraceae)
Stamens can also be adnate (fused or joined from more than one whorl):
  • epipetalous : adnate to the corolla
  • didynamous : occurring in two pairs of different length
  • tetradynamos : occurring as a set of six filaments with two shorter ones
  • exserted : extending beyond the corolla
  • included : not extending from the corolla.

Plant sexuality

In the typical flower (that is, the majority of flowering plant species) each flower has both a pistil and stamens. Bisexual plants are named hermaphrodites or perfect flowers.
In some species, however, the flowers are unisexual with only either male or female parts (monoecious = on the same plant; dioecious = on different plants). A flower with only male reproductive parts is called androecious. A flower with only female reproductive parts is called gynoecious
A flower having only functional stamens is called a staminate flower.
An abortive or rudimentary stamen is called a staminodium, such as in Scrophularia nodosa.
The pistil and the stamens of orchids are fused into a column. The top part of the column is formed by the anther. This is covered by an anther cap the anther cap coveres the anther.

Gallery

wheat at anthesis showing stamens.

References

anther in Catalan: Estam
anther in Czech: Tyčinka (botanika)
anther in German: Staubblatt
anther in Spanish: Estambre
anther in Esperanto: Stameno
anther in French: Étamine
anther in Ido: Stamino
anther in Indonesian: Benang sari
anther in Italian: Stame
anther in Latin: Stamen
anther in Lithuanian: Kuokelis
anther in Dutch: Meeldraden
anther in Japanese: 雄蕊
anther in Norwegian: Pollenbærer
anther in Polish: Pręcik (botanika)
anther in Portuguese: Estame
anther in Russian: Тычинка
anther in Finnish: Hede
anther in Swedish: Ståndare
anther in Turkish: Erkek organ (çiçek)
anther in Ukrainian: Тичинка
anther in Chinese: 雄蕊
Privacy Policy, About Us, Terms and Conditions, Contact Us
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2
Material from Wikipedia, Wiktionary, Dict
Valid HTML 4.01 Strict, Valid CSS Level 2.1