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1. Occurrence:
Bryophytes are mostly semi-terrestrial; grow in moist and shady places. They form green mats on damp soil, rocks, walls and tree trunks, especially during rainy season.
Some are aquatic (e.g. Riella, Riccia fluitans), a few grow as epiphytes (e.g., Porella, Dendroceros) and some known to be saprophytes (e.g., Buxbaumia aphylla, a moss; Cryptothallus mirabilis, a liverwort).
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2. Life cycle:
Haplodiplontic type, characterized by heteromorphic alteration of generation and sporogenic meiosis.
3. Dominant Plant Body:
Gametophyte is the dominant plan t body which is green long-lived and independent. The gametophyte is a thallus consists of rhizoids, axis (=stem) and leaves.
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4. Absence of Vascular Tissues:
Bryophytes have no vascular tissue for conduction of water and food. In place of xylem it carries Hadrome & in place of Phloem it carries Leptome. Arrangement is Hadrocentric.
5. Rhizoids:
Rhizoids are unicellular or multi-cellular root-like structures for absorption and anchorage. True roots absent.
6. Vegetative reproduction:
It takes place by various methods like:
(a) Death and decay old parts of the thallus,
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(b) By adventitious branches, or
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(c) By special structures like tubers, gemmae (produced in gemma cups, e.g., Marchantia) and protonema.
7. Sexual reproduction:
The sexual reproduction is oogamous type, i.e., the fusion of non-motile egg with motile biflagellate antherozoid (male gamete) form a diploid zygote.
8. Sex organs:
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Sex organs are multi-cellular and jacketed i.e. protected by sterile cell layer. They are of 2 types, i.e. antheridia (Club-shaped male sex organs) and archegonia (flask-shaped female sex organ). Antheridium has a short stalk with ovoid or club-shaped body.
The body filled with androcyte mother cells. Each androcyte mother cell diagonally divides into 2 androcytes and each androcyte metamorphosed into a biflagellate male gamete called antherozoid. Archegonium consists of a short stalk, flask-shaped venter and a tubular neck. Venter is 1-2 layered and encloses two cells i.e. an egg and a venter canal cell. Neck is single layered and encloses 5- 6 rows of cells.
9. Fertilization:
Water is essential for fertilization as a medium for transport of antherozoids to reach at archegonia. Fertilization results are the formation of diploid zygote which retains in the venter of archegonium for further development.
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10. Embryo:
The zygote is the first cell of sporophyte generation. The zygote develops into a multi-cellular embryo which stays for short duration and then develops into a sporophyte. Because of embryo formation bryophytes are included in Embryophyta.
11. Sporogonium:
The sporophyte of a bryophyte is called sporogonium which consists of foot, seta and capsule. The sporogenous cells of capsule develop into spore mother cell after repeated divisions.
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12. Spores:
Each spore mother cell undergoes meiosis to form four haploid spores. Thus, the spores produced inside the capsule of bryophytes are meiosporcs and homosporous similar types). A spore is the first cell of gametophyte generation. In liverworts, spores germinate into young gametophyte. However, in mosses each spore germinates into a juvenile stage called protonema, from which erect gametophores (adult gametophytes) develop.
