Rhodophyta- Florideophycidae
Sexual Reproduction-1

Sexual Reproduction in the Rhodophyta is generally Oogamous. This means that the Egg is significantly larger than the Sperm.

The Gametes in the Rhodophyta are both NONMotile

Gametangia

TEM Image of a Carpogonium with Trichogyne

The Male Gametangium is called a Spermatangium.

It produces nonmotile gametes called Spermatia (Sperm). However, we can call them Sperm!

The Female Gametangium is called a Carpogonium.

It produces a non-motile Egg. The Carpogonium is a Single Cell!

The Carpogonium produces an outgrowth called the Trichogyne (Female Hair). This is a Receptive Hair to which compatible sperm can bind.


Female Thallus of Bostrychia with Trichogynes (white hairs)	Detailed view of the left-hand image showing the Trichogynes and Carpogonia.

GeneralRedAlgalLifeCycle.gif (19144 bytes)

Generalized Sexual Reproductive Cycle for a Red Alga (Florideophyceae)

The Female Gamete is retained on the Gametophyte

Fertilization (->2N) occurs in situ.

A Minute Diploid Sporophyte grows inside the Carpogonium. It is called the CarpoSporophyte. It is retained on the Gametophyte.

It produces Carposporangia which form Diploid Spores called Carpospores.

These are released and germinate to form another Diploid Organism which is called the Tetrasporophyte. The name means that it is a Sporophyte that will produce Meiospores which form a Tetrad following Meiosis.

Tetraspores are produced in a Tetrasporangium.

The mature Tetraspores (N) are released and germinate to produce Haploid Gametophytes (Male or Female). These will form Gametangia when they are mature and begin the life cycle all over again.

This may seem complex but it only inserts an
additional Diploid Phase (Carposporophyte) in the Life Cycle.

Rhodophyta- Florideophycidae Sexual Reproduction-1