Come on friends today we will know about Androecium. The stamen ( plural stamens or stamens ) is the pollen – producing reproductive organ of a flower . Collectively, the stamens make up the androecium.
Morphology and Terminology
The stamens usually consist of a stalk called a filament and an anther containing microsporangia . The anthers are usually two-lobed and attached to the filament either at the base or in the central region of the anther. The sterile tissue between the lobes is called the connective , an extension of the filament containing the conducting strands. It can be seen as an extension on the dorsal part of the anther. A pollen grain develops from a microspore in the microsporangium and contains the male gametophyte .
The stamens in a flower are collectively called the androecium . Androecium may have at least one-half of the stamens (ie a single locus ) , as in the Cana species, or the 3,482 stamens counted in the saguaro ( Carnegie gigantea ). [2] Androecium forms a wide variety of patterns in different plant species, some of them highly complex. [3] [4] [5] [6] It usually surrounds the gynoecium and is surrounded by the perianth . some members of the family Triuridaceae, specifically Lacandonia schismatica , are exceptional in that their gynoecia surround their androecia.
Word – Medium
- Stamen is Latin meaning “thread” (originally the word thread , in warp knitting). [7]
- Filament is derived from Classical Latin filum, meaning “thread” [7]
- Anther derived from French anthre, [ 8] from Classical Latin anthera, meaning “medicine extracted from flower” [9] [10] in turn from Ancient Greek ( anthrá ), [8] [10] the noun ( anthrós ) meaning “flower”, [11] to 8 meaning “flower” [11]
- Pumang (plural androecia ) derived from Ancient Greek (aner ) meaning “man”, [11] and ( oikos ) meaning “house” or “room/room”.
Difference in morphology
Depending on the plant species, the flower may have some or all of the stamens attached to the petals or the floral axis . They can be erect or connected to each other in a number of different ways, including the fusion of some but not all of the stamens. Filaments may fuse and anthers may be free, or filaments may be free and anthers fuse. Instead of having two loci, one locus of a stamen may fail to develop, or alternatively the two locus may merge late in development to give a single locus. [12] Extreme cases of stamen fusion occur in some species of Cyclanthera in the family Cucurbitaceae and in the section Phyllanthus of the Cyclanthera genus(family Euphorbiaceae) where the stamens form a ring around the zygote, with a single locule.
Pollen production
A typical anther contains four microsporangia. Microsporangia form sacs or pockets ( locules in anthers) (anther sacs or pollen sacs). Two different spots on each side of an anther can merge into a single space. Each microsporangium is lined with a nutritive tissue layer called the tapetum and initially contains diploid pollen mother cells. They undergo meiosis to form haploid spores. Spores may remain attached to each other in tetrads or may separate after meiosis. Each microspore then divides mitotically to form an immature microgametophyte called a pollen grain.
The pollen is finally released when the anthers open (dehisis). These may include longitudinal slits, pores, as in the heath family (Ericaceae), or by valves, as in the barberry family (Berberidaceae). In some plants, notably members of the Orchidaceae and Asclepiaidoideae, pollen resides in masses called pollinators, which are adapted to attach to specialized pollinating agents such as birds or insects. More commonly, mature pollen grains are separated and spread by wind or water, pollinating insects, birds, or other pollination vectors.
For successful pollination, pollen from angiosperms must be delivered to the receptive surface of the carpel , the stigma of a corresponding flower . After arriving, the pollen grain (an immature microgametophyte) usually completes its development. It can develop a pollen tube and undergo mitosis to produce two sperm nuclei.
Sexual reproduction in plants
In the typical flower (that is, in most flowering plant species) each flower has both a carpel and a stamen . In some species, however, the flowers are bisexual with only carpels or stamens. ( monogamous = both types of flowers found on the same plant; dioecious = two types of flowers found only on different plants), a flower with only stamens is called androcious . A flower with only carpels is called a gynoecium .
A flower that has only functional stamens and lacks functional carpels is called a staminate flower , or (incorrectly) male. [14] Plants with only functional carpels are called pistillate or (incorrectly) female. [14]
An abortive or rudimentary stamen is called a staminodium or staminode , as in Scrophularia nodosa .
The carapace and stamens of orchids are fused into a single column. The top part of the column is formed by anther, which is covered with anther .
descriptive words
flower-saffron
The stamens may also be ascendant (fused or joined by more than one whorl):
- Epipetalus : Adapted to the corolla
- epiphyllous : Ascendant to the undifferentiated tepals (many forms of Liliaceae)
They can have different lengths from each other:
- Didymus : Two equal pairs
- Didynamus : Occurs in two pairs, a long pair and a short pair
- Quadrangular : Occurs as an aggregate of six stamens with four long and two short stamens
Of or relating to the rest of the flower (perianth):
- Presented : Extend beyond Corolla
- Included : Not moving beyond Corolla
They can be arranged in one of two different patterns:
- Spiral ; either
- whorled : one or more discrete whorls (series)
They can be arranged with respect to the petals:
- Diplostemonous : In two whorls, the outer petals turn along, while the inner petals are opposite.
- Haplostemenes : having a single series of stamens, equal to the appropriate number of petals and alternating with them
- obdiplostemonous : in two cores , with stamens twice as long as petals, opposite the outer petal, unlike the inner sepals, for example Simaroubaceae ( see diagram )
connective
Where the connective is very short, or imperceptible, the anther lobes are close together, and the connective is said to be discrete , eg Euphorbia pp., Adhoda zeylenica . Where the connective anther separates the lobes, it is said to split into two branches , e.g. Tilia , Justicia gendarussa . The connective can also be long and stalk-like, crosswise on the filament, a deviate connective, like in Salvia . Connectives can also bear appendages and are called appendiculates , such as Nerium odorum and some other species of Apocynaceae. in Nerium, the appendages are united to form a staminal halo.fiber
The column formed by the fusion of several fibers is known as an androphore . The stamens may be congenital (fused or joined into a single whorl) as follows:
- extrorse : anther dehiscence directed away from the center of the flower. c f introverted , directed inward , and latros laterally . [15]
- monadelphous : fused into a single, compound structure
- Declination : to turn downward, then upwards at the ends (also – descending – descending)
- diadelphous : partially joined by two androecial structures
- Pentadelphus : Partially joined by five androfacial formations
- synandrous : Only anthers are parental (such as Asteraceae). The fused stamens are called synandrium .
anther
Other shapes are described variously by terms such as linear , round , sagittal , sinuous , or reniform .
The anther can be attached to the filament in two ways: [16]
- Basicfixed : attached to the filament at its base
- Pseudobasicfixed : A somewhat misnomer configuration where the connective tissue filament extends into a tube around the tip
- dorsifixed : attached to the filament in its center, usually versatile (able to move)
