Question

shortnote on androecium

Answer 1

In some families of the order, the androecium (stamens) is constructed on a two-part (dimerous) or a four-part (tetramerous) plan, both of which are associated with regular corollas. For example, species of Oleaceae (e.g., ashes, forsythias, jasmine, and lilacs) typically have two stamens, and species of Buddleja (butterfly bush; a member of Scrophulariaceae) typically have four. In other families of the order, the androecium is constructed on a five-part (pentamerous) plan, associated mostly with corollas that are irregular. In these species departures from a full set of five stamens derive clearly from the suppression of one or more of the five. Thus, a few members of the order have five stamens (as in the mulleins; members of Scrophulariaceae), but most have only two or four. Species with four stamens (an upper pair and a lower pair) lack only the uppermost stamen. Other species lack the uppermost stamen and either the upper or the lower pair, leaving only two stamens. Any of the lost stamens may be represented by a staminode, or sterile stamen, borne in place of a normal stamen but not producing pollen. Depending on the species, a staminode may range from a minute projection on the inner surface of the corolla to an elongated filament-like structure equal in size and conspicuousness to the normal stamens (e.g., penstemon). In most species of the order, the stamen filaments are united with the petals (epipetaly), the degree of union ranging from slight to considerably more than half the length of the stamen. The stamens are alternate with the lobes of the corolla; that is, they are attached between the petals. In some highly irregular flowers, the alternate arrangement is difficult to see. The anthers of all members of the order have four pollen sacs. Pollen form and structure are exceedingly diverse. One family of the order, Acanthaceae, shows a wider range of pollen morphological features than almost any other family of flowering plants.

Answer 2

Answer:

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Shortnote on androecium!!

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Androecium

it is the third whorl of the flower which arises inner to the corolla. It is the male reproductive system which is composed of stamens. A stamen consists of a filament and anther. Anthers are usually bilobed. Each lobe contains two microsporangia or pollen sacs. The pollen grains are produced in pollen sacs. A sterile stamen is called staminode. There may be a variation in the length of filaments within a flower, as in Salvia and mustard.

Adhesion of stamens :

The stamen may be attached to other floral organs such as petals, sepals etc. When a stamen is attached to the petal, then it is called epipetalous e.g., brinjal and when the stamen is attached to the perianth then it is said to be epiphyllous e.g., lily.

Cohesion of stamens :

The stamens may be free or united. When the stamens are free then they are called polyandrous and when stamens are united in a single bundle, then it is called monoadelphous, as in china rose, when they are united in two bundles, then it is called diadelphous e.g. pea and when united into more than two bundles it is called polyadelphous e.g., Citrus