Sexual Reproduction in Flowering Plants

These flashcards cover the key vocabulary and biological concepts related to the morphology and development of male and female reproductive structures in flowering plants as detailed in Chapter 2.

Floriculture

The study and cultivation of flowers for aesthetic, ornamental, social, religious, and cultural value.

Androecium

The male reproductive organ of a flower which consists of a whorl of stamens.

Gynoecium

The female reproductive organ of a flower which represents the pistil and can be monocarpellary or multicarpellary.

Filament

The long and slender stalk that forms one of the two parts of a typical stamen.

Anther

The terminal generally bilobed structure of a stamen which is typically dithecous and tetragonal.

Dithecous

A characteristic of an angiosperm anther where each of its two lobes contains two theca.

Microsporangia

Four structures located at the corners of a tetragonal anther, two in each lobe, that develop further into pollen sacs.

Tapetum

The innermost wall layer of a microsporangium that nourishes developing pollen grains and possesses dense cytoplasm with more than one nucleus.

Sporogenous tissue

A group of compactly arranged homogenous cells occupying the centre of each microsporangium in a young anther.

Microsporogenesis

The process of formation of microspores from a pollen mother cell (PMC) through the process of meiosis.

Pollen grains

The male gametophytes, which are generally spherical and measure about $25\text{--}50\text{\thinspace micrometers}$ in diameter.

Exine

The hard outer layer of a pollen grain made of sporopollenin, which is one of the most resistant organic materials known.

Sporopollenin

A highly resistant organic material that can withstand high temperatures and strong acids or alkali, and for which no degrading enzyme is currently known.

Germ pores

Prominent apertures in the pollen grain exine where sporopollenin is absent.

Intine

The thin and continuous inner wall of a pollen grain, composed of cellulose and pectin.

Vegetative cell

The larger of the two cells in a mature pollen grain, containing abundant food reserves and a large irregularly shaped nucleus.

Generative cell

The smaller, spindle-shaped cell of a pollen grain that floats in the vegetative cell's cytoplasm and contains dense cytoplasm and a nucleus.

Parthenium

Also known as carrot grass, it is a plant that came to India as a contaminant with imported wheat and is a common cause of pollen allergy.

Pollen Viability

The period for which pollen grains remain functional; it is as short as $30$ minutes in rice and wheat, or as long as months in Rosaceae and Solanaceae.

Cryopreservation of Pollen

Maintaining the viability of pollen grains for years by storing them in liquid nitrogen at $-196^{\circ}\text{C}$.

Syncarpous

A condition in a multicarpellary gynoecium where the pistils are fused together, such as in Papaver.

Apocarpous

A condition in a multicarpellary gynoecium where the pistils are free, such as in Michelia.

Placenta

The structure located inside the ovarian cavity (locule) from which megasporangia (ovules) arise.

Funicle

The stalk by which an ovule is attached to the placenta.

Hilum

The region where the body of the ovule fuses with the funicle, representing the junction between the two.

Integuments

One or two protective envelopes that encircle the nucellus of an ovule, except at the tip.

Micropyle

A small opening at the tip of the ovule where the integuments are not present.

Chalaza

The basal part of the ovule, located opposite the micropylar end.

Nucellus

A mass of cells enclosed within the integuments that contains abundant reserve food materials and the embryo sac.

Megasporogenesis

The process of formation of megaspores from the megaspore mother cell (MMC).