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bryophytes.pptxforbotany [Autosaved].pptx

The document details the adaptations of bryophytes as they evolved from algae to land plants, highlighting their key adaptations for water conservation, reproduction, and structural organization. It describes the various forms of gametophytes in bryophytes, including thalloid and leafy types, with examples such as Marchantia and Funaria, emphasizing their reproductive structures and mechanisms. Additionally, it provides an overview of the internal structure of the sporophyte in Funaria, including its development stages and reproductive processes.

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Adaptations of Bryophytes to Land Habit:  First land plants.  Evolved from Algae.  During the process of origin they developed certain adaptations to land habit.
1. Development of compact, Multicellular plant body covered with epidermis for conservation of water. 2. Development of organs for attachment and absorption e.g., rhizoids.
3. Development of photosynthetic tissues into special chambers for the absorption of carbon dioxide without losing much water and exposure to light. e.g., airpores.
4. Protection of reproductive cells i.e., jacketed sex organs. 5. Heterogamy: was evolved, forming non-motile egg containing stored food and motile sperms.
6. Retention of zygote within the archegonium. 7. Multicellular embryo was formed which was retained inside the female reproductive body during its development
8.Production of large number of thick walled spores. 9. Dissemination of spores by wind.
10. Alternation generation Enabled the plant to produce and test the best genetic combinations for adapting to the versatile terrestrial conditions.
Range of thallus organization In Bryophytes
Gametophyte (dominant generation) In simplest form of bryophytes gametophyte is green, Independent, one to several layer thick, without any internal differentiation of tissue, e.g. Sphaerocarpus, Pellia and other Hepaticae Two divergent line of descents
Range of gametophyte in thalloid form e.g Marchantials Range of gametophyte in leafy form, e.g. Musci (Gametophyte reaches to highest development, the erect leafy shoot with its radial symmetry, showing differentiation in form and structure
Range of gametophyte in thalloid form •Plant body simple thallus •Flat, prostrate, dorsiventral, •Usually dichotomously branched
Sphaerocarpos, Anthoceros, Pellia , Riccia, Marchantia
Anthoceros
•Most simple thallus •Thallus is prostrate, dorsiventrally differentiated, rarely dichotomously branched and also has a dark- green colour.
•Thallus variously lobed without a sharply defined midrib. •Air-chambers and scales are absent, •Slit-like pores and smooth rhizoids are present on the under surface of the thallus.
Pellia
•Plant body is thin, dorsiventral, prostrate, dichotomously branched, with somewhat wavy margin. •Apical portion is notched, in which growing point (Apical cell ) is located
•The dorsal surface is almost smooth and a median midrib is prominent. •Numerous smooth, unicellular rhizoids under the midrib. •Scales absent
Riccia
Plant body is thallose, dorsiventrally prostate with dichotomous branching. There is a conspicuous longitudinal furrow on the dorsal side.
•The ventral surface bears a corresponding ridge and a transverse row of scales, •Scales one cell in thickness, which are more crowded near the apex and overlap the growing point.
Lower down, the scales are in two marginal rows, violet in colour. Two types of rhizoids – smooth walled and tuberculate, being on the ventral ridge of the thallus.
Marchantia
•Dorsal surface of the thallus shows regular rhomboidal or polygonal areas with elevated pores at the centre of these areas
•Ventral surface bears 3-4 rows of scales on each side of the ridge. •There are two types of rhizoids in between the scales – smooth-walled and tuberculate.
•Range of gametophyte in leafy form •Leafy Jungermanniales (Porella) and in Bryopsida ( Sphagnum, Funaria, Polytrichum, Pogonatum)
Porella
Plant body is flat, dorsiventral with a bi- or tripinnately branched leafy axis with no rhizoids in mature plants.
•There are 3 rows of leaves – 2 lateral and one smaller row on the ventral side termed amphigastria •Leaves are thin without midrib and one cell in thickness.
•Lateral leaves are two-lobed •Upper larger lobe is antical lobe •Lower smaller lobe is the postical lobe or lobule.
Sphagnum
•Bog Moss or Peat Moss •Plant body is erect, leafy, and bears rhizoids at the base (when young). •The stem has whorls of lateral branches at intervals.
•Pendent and Divergent branches •Leaves show dimorphic leaf cell: (a) Hyaline cells and (b) Chlo­ rophyllose cells.
•Leaves are small, thin without midrib and spirally arranged on the axis. • The main stem has fewer leaves. The leaves are sessile ovate-elongate, with smooth margin and acute apex.
Funaria
•The plant body is erect, branched with spirally arranged leaves. •The leaves are more crowded near the apex like a rosette • Arranged in three rows.
•Leaves are sessile, attached to the stem by a broad base, ovate-elongate, pointed at the apex and with a smooth margin and midrib. •The plant bears rhizoids at the base.
•Rhizoids are multicellular with oblique cross walls. •Brown and form tangled mass
Polytrichum
•Underground rhizome and erect leafy shoot •Rhizome bear numerous multicellular rhizoid
•Plants body is erect, leafy and dioecious. •Presence of specialized stem core tissue – leptoids and hydroids,
•Peristome teeth 32 in number and arranged in a ring •Capsule round
Pogonatum
•Plant body is erect, somewhat rhizomatous and stem is covered by spirally arranged leaves. •Numerous rhizoids develop from the base of the stem.
•The rhizoids are multicellular with oblique cross walls.
•Leaves are spirally arranged, more crowded and larger near the apex. •The base of the leaf is broad, partly sheathing and pale.
•Leaves are gradually tapering, with serrate margin, acute apex and a midrib.
Marchantia
Internal structure