BRYOPHYTA KEY CONCEPTS ( NEET )
(1) Bryophyta (Gk: Bryon = moss; phyton = plants) includes the simplest and primitive land plants.
(2) Due to the peculiar type of their habitats, they are regarded as 'the amphibians of the plant kingdom'.
(3) Habitat: Bryophytes usually grow in moist and shady places.
(4) Specialized habitats: Some bryophytes grow in diverse habitats such as
(a) Aquatic (e.g., Riccia fluitans, Ricciocarpus natans, Riella), epiphytes (e.g., Dendroceros, Radula protensa and many mosses), saprophytes (e.g., Buxbaumia aphylla, Cryptothallus mirabilis)
(b) Dry habitats such as dry heaths (e.g., Polytrichum juniperinum), deserts (e.g., Tortula desertorum) and dry rocks (e.g., Porella platyphylla).
(5) Sexual reproduction: The male sex organ is called as antheridium and the female as archegonium.
(6) Salient features of classes
(i) Hepaticopsida: The latin word Hepatica means liver. Thus the members of hepticopsida are popularly known as liverworts.
(ii) Anthocerotopsida: This class is characterized by the following characters
(a) Gametophyte is thalloid. Thalli are lobed, dorsiventral, and internally homogenous without any differentiation of tissues.
(b) Air chambers and air pores are absent but mucilage cavities may be present.
(c) Rhizoids are only smooth walled.
(d) Scales are absent.
(e) Each cell possesses a single (some times more) large chloroplast with central pyrenoid.
(f) Oil bodies are absent.
(g) Antheridia are endogenous in origin, borne singly or in groups inside the closed cavities.
(h) Sporogonium is differentiated into foot, meristematic zone and capsule (the seta is absent).
(i) Capsules have central sterile columella.
(iii) Bryopsida: The members of bryopsida are commonly known as mosses. The class is characterised by the following characters
(a) Gametophyte is differentiated into two stages – prostate protonema and erect radial leafy shoot.
(b) Leaf-like appendages are spirally arranged on the stem – like axis.
(c) Rhizoids are multicellular with oblique septa.
(d) Sex organs develop from superficial cells.
(e) Sporogonium is differentiated into foot, seta and capsule.
(f) Wall of the capsule is several layered with a stomata on the epidermis.
(g) The capsule has a central columella.
(h) Elaters are absent.
