(Gk. Bryon = moss; phyton = plants)
Bryophyta includes the simplest and primitive land plants. Which are characterised by the persence of independent gametophyte and parasitic sporophyte. The term bryophyta was coined by Braun (1864) but bryophytes were delimited in its present form by Schimper (1879). It occupies a position intermediate between algae and pteridophyta. Due to peculiar type of their habitats, they are regarded as 'the amphibians of the plant kingdom'. The science connected with the study of bryophytes called bryology.
Bryophytes usually grow in moist and shady places. The plants grow densely together and form green carpets or mats on damp soil, rock, walls, barks of trees and on decaying logs in forests, especially during the rainy season.
Specialized habitats : Some bryophytes grow in diverse habitats such as – aquatic (e.g., Riccia fluitans, Ricciocarpus natans, Riella), epiphytes (e.g., Dendroceros, Radula protensa and many mosses), saprophytes (e.g., Buxbaumia aphylla, Cryptothallus mirabilis), and in dry habitats such as dry heaths (e.g., Polytrichum juniperinum), deserts (e.g., Tortula desertorum) and dry rocks (e.g., Porella platyphylla).
Gametophytic plant body
(1) The life cycle of bryophytes consists of two distinct phases – the gametophytic phase and the sporophytic phase. The haploid gametophyte is dominant, long lived, green and independent whereas the diploid sporophyte is short lived and dependent upon the gametophyte. The two phases are morphologically distinct.
(2) The plants are small, range from few millimetres (e.g., Zoopsis) to 30–40 centimetres. The tallest species may reach upto 70 cm in length (e.g., Dawsonia).
(3) The gametophytes are either thalloid (i.e., not differentiated into true roots, true stem and true leaves) or leafy shoot having stem-like central axis and leaf-like appendages.
(4) The roots are completely absent and they are replaced by unicellular or multicellular thread like rhizoids. In some higher forms the multicellular rhizoids form cords.
(5) The vascular tissue (i.e., xylem and phloem) are completely absent.
(1) Vegetative reproduction : The bryophytes reproduce vegetatively by following methods :
Death and Decay : Most of these plants reproduce vegetatively by gradual death and decay of the older part of the plant body.
Adventitious branches : Many plants like Riccia fluitans, Reboulia, Asterella, Pellia etc. reproduce by adventitious branches. They separate and produce new plants.
Tubers : Several species of Riccia, Anthoceros, Sewardiella, Asterella etc. produce tubers which give rise to new plants on the arrival of favourable conditions.
Gemmae : Several members, reproduce vegetatively by forming multicelled gemmae. In Marchantia, Lunularia, the gemmae are produced in gemma cups. 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).
Primary protonema : The mosses generally reproduce vegetatively by breaking of the primary protonema. New gametophores now arise from the buds differentiated on it.
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 more...