plant reproduction

Alternation of generations

The plant life cycle that alternates between a multicellular haploid generation n and a multicellular diploid generation 2n

Gametophyte

The multicellular, haploid n phase of the plant life cycle that produces haploid gametes (sperm and eggs) via mitosis.

Sporophyte

The multicellular, diploid 2n phase of the plant life cycle that produces haploid spores via meiosis.

Stigma

The sticky or receptive surface at the top of the carpel designed to capture pollen grains.

Style

The elongated neck of the carpel connecting the stigma down to the ovary

Ovary

The swollen base of the carpel that houses the ovules; it matures into the fruit after fertilization.

Ovule

A structure within the ovary containing the female gametophyte; it develops into a seed after fertilization.

Carpel

The entire female reproductive organ of a flower, consisting of the stigma, style, and ovary.

Anther

The pollen-producing sac located at the top tip of a stamen.

Filament

The slender, stalk-like structure of the stamen that supports and elevates the anther.

Stamen

The complete male reproductive organ of a flower, consisting of the filament and the anther.

Floral meristem

A modified shoot apical meristem that has transitioned from producing leaves to producing the reproductive structures of a flower.

Organ identity genes

Regulatory master genes (such as MADS-box genes) that direct the development of specific floral organs according to the ABC model.

Whorls

Concentric circular rings of flower parts; from outside to inside, they consist of sepals, petals, stamens, and carpels.

Monoecious

A plant species that has separate male and female flowers residing together on the sameindividual plant (e.g., corn).

Dioecious

A plant species where individual plants are strictly male or strictly female, containing only staminate or only carpellate flowers (e.g., willow).

Fruit

A matured, ripened ovary of a flower that protects dormant seeds and aids in their dispersal.

Simple fruit

A fruit that develops from a single carpel or several completely fused carpels of a single flower (e.g., a cherry or tomato)

Multiple fruit

A cluster of fruit structures that develops from an inflorescence—an entire tightly packed group of separate flowers (e.g., a pineapple).

Aggregate fruit

A fruit that develops from a single flower that contains multiple, separate, unfused carpels clustered together (e.g., a raspberry).