Sexual Reproduction in Flowering Plants

A comprehensive set of vocabulary flashcards covering the reproductive structures, processes, and post-fertilization developments in flowering plants as described in the lecture notes.

Sexual reproduction

The process of development of new organisms through the formation and fusion of gametes.

Flowers

Modified condensed reproductive shoots that serve as the organs specialized for sexual reproduction in angiosperms.

Thalamus

The broad base of a typical flower over which the four whorls of floral leaves (sepals, petals, stamens, and carpels) are borne.

Stamen

The male reproductive organ or microsporophyll of a flower, consisting of a filament and an anther.

Anther

The broader knob-like fertile part of the stamen, typically bilobed and tetrasporangiate, where pollen grains are produced.

Connective

A sterile parenchymatous tissue containing a vascular strand that attaches the two anther lobes to each other.

Endothecium

A layer of the microsporangial wall whose cells often develop fibrous thickenings of $\alpha$-cellulose; it is also called the fibrous layer.

Tapetum

The innermost layer of the microsporangial wall that nourishes developing microspore mother cells and pollen grains.

Stomium

The line of dehiscence in an anther lobe where hypodermal cells remain thin-walled between two microsporangia.

Microsporogenesis

The phenomenon of meiotic formation of haploid microspores or pollen grains from a diploid microspore mother cell ($PMC$).

Pollinium

A single sac in which all the pollen grains of an anther lobe remain united, as seen in Calotropis.

Sporoderm

The wall or covering of a pollen grain consisting of two layers: the outer exine and the inner intine.

Sporopollenin

A highly resistant fatty substance making up the exine that is not degraded by enzymes and is unaffected by high temperature, strong acid, or strong alkali.

Palynology

The study of the external morphology of mature pollen grains.

Pollen Viability

The period for which pollen grains retain the ability to germinate, which varies from 30 minutes in rice to months in some family members of Solanaceae.

Gynoecium

The female component of a flower which may consist of one or more carpels (megasporophylls).

Syncarpous

A condition where the carpels of the gynoecium are fused, such as in Hibiscus or Papaver.

Apocarpous

A condition where the carpels of the gynoecium are free, such as in Michelia or Ranunculus.

Ovule

An integumented megasporangium found in spermatophytes which develops into a seed after fertilization.

Funiculus

The stalk that attaches an ovule to the placenta.

Nucellus

A mass of parenchymatous cells in the body of the ovule that is equivalent to a megasporangium.

Megasporogenesis

The process of meiotic formation of haploid megaspores from a diploid megaspore mother cell ($MMC$).

Double Fertilization

A phenomenon unique to angiosperms involving two acts of fertilization: generative fertilization (syngamy) and vegetative fertilization (triple fusion).

Triple Fusion

The fusion of a second male gamete with two polar nuclei (or a diploid secondary nucleus) to form a triploid primary endosperm nucleus ($PEN$).

Siphonogamy

The process in seed plants where male gametes are brought to the egg by a pollen tube.

Endosperm

A food-laden tissue formed from triple fusion that is meant for nourishing the embryo in seed plants.

Embryogeny

The sum total of changes that occur during the development of a mature embryo from a zygote or oospore.

Scutellum

The single large cotyledon of the grass family, situated towards the lateral side of the embryonal axis.

Coleoptile

A hollow foliar structure in monocot embryos that encloses the shoot apex and leaf primordia.

Coleorhiza

An undifferentiated sheath in monocot embryos that encloses the radicle and root cap.

Perisperm

The residual nucellus that persists in certain seeds, such as black pepper or coffee.

Parthenocarpy

The production and development of seedless fruits without fertilization, either naturally or induced by hormones.

Apomixis

A mode of reproduction mimicking sexual reproduction that produces seeds without fertilization.

Polyembryony

The phenomenon of having more than one embryo in a single seed.