Reproduction in Riccia

In Riccia, reproduction takes place by vegetative and sexual means.

A. Vegetative reproduction

Following modes of vegetative reproduction is reported in Riccia:

By death and decay of older portion of the thallus (fragmentation)
By adventitious branching
By tubers
By rhizoids

1. Fragmentation

Thallus of Riccia are dichotomously branched. By death and decay older portion of the thallus is fragmented and each fragment divides to produce a separate thallus.

2. Adventitious branching

Adventitious branches are produced on the side of the thallus. When detached, these produce a new thallus. Example: R. fluitans.

3. Tuber

Tuber are oval bodies borne on the margin of thallus. After death and decay of thallus, tubers are separte. On getting favorable conditions, tubers germinate to produce new thalli. Example: R. bulbifera, R. discolor, R. perennis, R. vesicata.

4. Rhizoid

Tips of rhizoids divide repeatedly to form mass of chlorophyllous cells, which after detachment, produce a new thallus. Example: R. glauca

B. Sexual reproduction

Sexual reproduction in Riccia takes place by the male and female sex organs called as antheridium and archegonium respectively. These are borne in the mid dorsal grove of the thallus. The life cycle of Riccia show alternation of generation. Main plant body is thalloid gametophyte (n) and sporophyte (2n) represented by the capsule only is dependent upon the gametophyte. Water is essential for fertilization. Sporic meiosis occurs at the time of haploid spore formation.
Most of the species of Riccia are homothallic or monoecious, however some species of Riccia (e.g., R. discolor, R. sanguinea, R. frostii, R. pearsonii) are heterothallic or dioecious.

Male sex organ (antheridium)

First published on 13-04-2021
Last updated on 01-05-2021

See also

Reproduction in riccia