The reproduction takes place by means of vegetative, asexual and sexual methods.
1. Vegetative reproduction.
In majority of cases it takes place by fragmentation.
2. Asexual reproduction.
The asexual reproduction of the gametophytes takes place by neutral spores, monospores, and polyspores. The neutral spores develop in ordinary cells of thallus, e.g., Asterocystis. The monospores are developed in sporangia. A single spore develops in each sporangium, e.g., Scinaia. The polyspores are formed in larger number in the sporangium.
The asexual reproduction of the sporophytes takes place by tetraspores formed in tetrads in the tetrasporangia, e.g., Polysiphouia and paraspore borne inside parasporangium in greater numbers. During the development of tetraspores reduction division takes place. In the development of paraspores there is no reduction division.
3. Sexual reproduction:
The sexual reproduction is always oogamous. The oogamy is of special type. The sex organs of Rhodophyceae have a distinguished terminology. The male structures are called the spermatangia developing non-motile spermatia (male gametes) in them. The female sex organ is called the procarp. It has a carpogonium bearing a receptive structure trichogyne. The egg develops in the basal swollen part of carpogonium. The auxiliary cell may or may not be formed. In Ceramiales the auxiliary cell is formed after fertilization.
Zygote and its germination:
In sub-class Bangioideae the zygote divides by vertical and transverse divisions. The number of cells may be 2, 4, or 16. The spores are known as carpospores. They are naked and liberated by disintegration of zygote wall and move about in amoeboid fashion. The first division of the nucleus of the zygote is reductional. In sub-class Florideae the carpospores develop indirectly from the zygote.