Q.A sterile stamen is called

A sterile, non-pollen-producing stamen is called a staminode.

The androecium (male whorl) of a flower is made up of stamens, each typically consisting of a filament and an anther that produces pollen. In some flowers, one or more stamens fail to produce pollen and are reduced or modified in structure; such a sterile stamen is termed a staminode. It may sometimes be petal-like or serve other functions (e.g. as a nectary) rather than producing pollen.

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A flower's male reproductive whorl is the androecium, made up of individual units called stamens, each of which produces pollen (the male gametophyte) inside its anther.

A typical flower has four whorls arranged from the outside in: the calyx (sepals, protective), corolla (petals, often colourful to attract pollinators), androecium (stamens, the male reproductive whorl), and gynoecium (carpels/pistil, the female reproductive whorl at the centre). Each stamen consists of a slender stalk, the filament, topped by the anther — typically bilobed, with each lobe containing two microsporangia (pollen sacs) where pollen grains develop through meiosis.

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Monadelphous androecium — where filaments of all stamens unite into one bundle/tube — is the classic condition seen in Hibiscus (family Malvaceae).

In floral morphology, the cohesion of stamens (union among themselves) is described by special terms: monadelphous (all filaments fused into one bundle, e.g. Hibiscus, China rose), diadelphous (filaments united into two bundles, e.g. pea), and polyadelphous (filaments united into more than two bundles, e.g. Citrus). In Hibiscus, the many stamens have thei …

The androecium is the male reproductive whorl of a flower, made up of stamens that produce pollen.

A complete flower is built of four whorls, arranged from outside to inside: the calyx (sepals, protective), the corolla (petals, usually attractive/colourful), the androecium (the male whorl), and the gynoecium (the female whorl, at the centre). The androecium consists of one or more stamens; each stamen typically has a slender filament bearing a two-lobed anther at …

Gynoecium is the female part of the flower, and the stigma is one of its own component parts (borne on the pistil/carpel), so Gynoecium matches with Stigma.

The gynoecium (also called the pistil) is the innermost, female reproductive whorl of a flower, made up of one or more carpels. Each carpel typically has three parts: the ovary (the swollen basal part containing ovules), the style (the stalk-like middle part), and the stigma (the terminal, often sticky or feathery, receptive surface on which pollen grains land and germinate). Sin …

A flower with both androecium (male whorl) and gynoecium (female whorl) is called a bisexual flower.

A flower is described as bisexual (or hermaphrodite) when it possesses both the male reproductive whorl (androecium, made up of stamens) and the female reproductive whorl (gynoecium, made up of carpels/pistil) in the same flower. A flower having only one of the two — either an …

Reading the described branch (several open flowers along a leafy stem, with A near the top flower and B on a lower flower), the most externally obvious, easily-labelled parts on such a whole-branch diagram are the pedicel (the flower's stalk joining it to the main axis) and the calyx (the outermost, usually green, whorl of sepals visible on an open flower) -- matching option (d).

A flower has four whorls, from outside in: Calyx (sepals) -> Corolla (petals) -> Androecium (stamens) -> Gynoecium (carpels), all borne on a stalk called the pedicel, which itself arises from the main stem/axis. On a whole-branch drawing (rather than a magnified single-flower dissection), the parts most naturally labelled without cutting the flower open are the pedicel (visibly connecting flower to stem) and the calyx (the outer, often leaf-like sepals visible even on a mostly-closed or newly opened flower) -- the androecium and gynoecium are internal whorls that a simple line drawing of a branch would not usually resolve.

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