The bryophytes reproduce vegetatively, asexually and sexually. Various methods involve in reproduction are discussed in the following account.
# (i) Vegetative reproduction : The bryophytes reproduce vegetatively by following methods :
(a) Death and Decay : Most of these plants reproduce vegetatively by gradual death and decay of the older part of the plant body.
(b) Adventitious branches : Many plants like Riccia fluitans, Reboulia, Asterella, Pellia etc. reproduce by adventitious branches. They separate and produce new plants.
(c) Tubers : Several species of Riccia, Anthoceros, Sewardiella, Asterella etc. produce tubers which give rise to new plants on the arrival of favourable conditions.
(d) Gemmae : Several members, reproduce vegetatively by forming multicelled gemmae. In Marchantia, Lunularia, the gemmae are produced in gemma cups. In some liverworts, 1–3 celled gemmae are prodcued on the axis or on the 'leaves' or on thalli. Gemmae are also produced on the thallus of Anthoceros. Several mosses also produce gemmae on the 'leaves' (Bryum), or axis or rhizoids or on the protonema (Funaria).
(e) Leafy propagules : Some liverworts also reproduce vegetatively by forming leafy propagules.
(f) Primary protonema : The mosses generally reproduce vegetatively by breaking of the primary protonema. New gametophores now arise from the buds differentiated on it.
(g) Secondary protonema : In several mossess a secondary protonema may arise from the rhizoids or primary protonema or even from the injured sporophyte. It may produce buds which give rise to new gametophores.
(h) Rhizoids : Mosses may also reproduce vegetatively from the rhizoids e.g., Leucobryum.
# (ii) Sexual reproduction : The male sex organs is called as antheridium and the female as archegonium. The antheridial stalk is very distinct whereas the archegonial stalk is generally short. They may be of embedded type e.g., Riccia, Anthoceros or of projecting type e.g., Marchantia, mosses.
(a) Antheridia : They are generally borne on the dorsal surface of the thallus. While in Riccia the antheridial chambers are open, in Anthoceros they are closed. The antheridia lie embedded within the thallus in both the plants. In Jungermanniales the antheridia are borne in one or more rows. In Marchantiaceae they are present on a special branches, the antheridiophores or the male receptacles which may be stalked or sessile. While in most of the members the antheridia are superficial in origin, in Anthoceros they are endogenous. Each antheridium is distinguishable into a stalk and the body. The antheridial body consists of a mass of androgonial cells covered by a 1-cell thick sterile jacket. The terminal cell of the jacket, when distinct, is called as operculum. Each androgonial cell finally behaves as androcyte mother cell. The androcyte mother cell then forms two androcytes (antherozoid mother cell), each of which is metamorphosed into a biflagellate antherozoid.
(b) Archegonia : These are also borne on the dorsal surface of the thallus. In Riccia and Anthoceros they lie embedded in the thallus. In many members of Marchantiaceae they are borne on special branches called archegoniophores or the female receptacles, that may be stalked or sessile. The archegoniophore or carpocephalum has rows of archegonia protected by involucre or perichaetium. The archegonia are flask shaped structures distinguishable into a long neck and a globular, swollen venter. A multicelled stalk is also present in mosses but in others it is very short. The neck is one-cell thick. It is generally made up of six vertical rows of cells but in Jungermamnniales it is compose of 4 or 5 vertical rows only. The neck is capped by four cover cells and contain varying number of neck canal cells inside. While in Riccia there are only 4 neck canal cells, the mosses however, possess more than six of them. The venter is also 1-cell thick in most of the plant but in Jungermanniales it is 2–3 layered. In mosses it is double layered. The venter contains an egg and a ventral canal cell.
The bryophytes reproduce vegetatively, asexually and sexually. Various methods involve in reproduction are discussed in the following account.
# (i) Vegetative reproduction : The bryophytes reproduce vegetatively by following methods :
(a) Death and Decay : Most of these plants reproduce vegetatively by gradual death and decay of the older part of the plant body.
(b) Adventitious branches : Many plants like Riccia fluitans, Reboulia, Asterella, Pellia etc. reproduce by adventitious branches. They separate and produce new plants.
(c) Tubers : Several species of Riccia, Anthoceros, Sewardiella, Asterella etc. produce tubers which give rise to new plants on the arrival of favourable conditions.
(d) Gemmae : Several members, reproduce vegetatively by forming multicelled gemmae. In Marchantia, Lunularia, the gemmae are produced in gemma cups. In some liverworts, 1–3 celled gemmae are prodcued on the axis or on the 'leaves' or on thalli. Gemmae are also produced on the thallus of Anthoceros. Several mosses also produce gemmae on the 'leaves' (Bryum), or axis or rhizoids or on the protonema (Funaria).
(e) Leafy propagules : Some liverworts also reproduce vegetatively by forming leafy propagules.
(f) Primary protonema : The mosses generally reproduce vegetatively by breaking of the primary protonema. New gametophores now arise from the buds differentiated on it.
(g) Secondary protonema : In several mossess a secondary protonema may arise from the rhizoids or primary protonema or even from the injured sporophyte. It may produce buds which give rise to new gametophores.
(h) Rhizoids : Mosses may also reproduce vegetatively from the rhizoids e.g., Leucobryum.
# (ii) Sexual reproduction : The male sex organs is called as antheridium and the female as archegonium. The antheridial stalk is very distinct whereas the archegonial stalk is generally short. They may be of embedded type e.g., Riccia, Anthoceros or of projecting type e.g., Marchantia, mosses.
(a) Antheridia : They are generally borne on the dorsal surface of the thallus. While in Riccia the antheridial chambers are open, in Anthoceros they are closed. The antheridia lie embedded within the thallus in both the plants. In Jungermanniales the antheridia are borne in one or more rows. In Marchantiaceae they are present on a special branches, the antheridiophores or the male receptacles which may be stalked or sessile. While in most of the members the antheridia are superficial in origin, in Anthoceros they are endogenous. Each antheridium is distinguishable into a stalk and the body. The antheridial body consists of a mass of androgonial cells covered by a 1-cell thick sterile jacket. The terminal cell of the jacket, when distinct, is called as operculum. Each androgonial cell finally behaves as androcyte mother cell. The androcyte mother cell then forms two androcytes (antherozoid mother cell), each of which is metamorphosed into a biflagellate antherozoid.
(b) Archegonia : These are also borne on the dorsal surface of the thallus. In Riccia and Anthoceros they lie embedded in the thallus. In many members of Marchantiaceae they are borne on special branches called archegoniophores or the female receptacles, that may be stalked or sessile. The archegoniophore or carpocephalum has rows of archegonia protected by involucre or perichaetium. The archegonia are flask shaped structures distinguishable into a long neck and a globular, swollen venter. A multicelled stalk is also present in mosses but in others it is very short. The neck is one-cell thick. It is generally made up of six vertical rows of cells but in Jungermamnniales it is compose of 4 or 5 vertical rows only. The neck is capped by four cover cells and contain varying number of neck canal cells inside. While in Riccia there are only 4 neck canal cells, the mosses however, possess more than six of them. The venter is also 1-cell thick in most of the plant but in Jungermanniales it is 2–3 layered. In mosses it is double layered. The venter contains an egg and a ventral canal cell.