Q.10 Describe the structure of Marchantia and Anthoceros thallus with the help of comparative characters. (1994, 96)
Q. Distinguish the reproduction between marchantia and Anthoceros.
Ans.
Q.11. Give the longitudinal section sporophytes of any four Bryophytes studied by you. (1995, 97)
Related Questions -
Q. Describe the structure of sporophyte of Anthoceros. (2009, 11)
Q. Draw labelled diagram of sporophyte of following (i) Riccia (ii) Marchantia (iii) Pellia (iv) Anthoceros (2007)
Q. Draw well labelled diagram of V. L.S. sporophyte of Marchantia. (2004)
Q. Draw the LS. of Pellia sporophyte. (2004)
Ans. L.S. of sporophyte of Riccia: -
The mature sporophyte of Riccia represented by spore sac or capsule only which is embedded on the dorsal surface of the gametophyte. Foot and seta are absent. The spore mother cell enclose by a single layered sterile jacket.
The capsule covered by two layered calyptra. The capsule wall degenerates before the division of spore mother cell and after some time the inner layer of calyptra disintegrated partly. Thus at this stage the spores of Riccia, which represent the new gametophytic generation are housed in the cavity of old gametophyte. This is anomoly in which the new gametophyte is enclosed with in the old-gametophyte. Thus in a mature sporophyte spore tetrads lie in a cavity enclosed by a single layered calyptra.
2. L. S. of Sporophyte of Marchantia - The sporophyte of Marchantia more advanced than the Riccia. The mature sporophyte is differentiated into the foot, seta and capsule.
(i) Foot - It is basal broad and bulbous part of sporophyte made up of parenchymatous cells, the foot absorbs the nutrients and water and anchors the developing sporophyte to the disc of the archegonium.
(ii) Seta - It is short, stalk that connects foot to the capsule. It is made up of parenchymatous cells. At the maturation of the capsule these cells undergo transverse division and elongation.
Thus, seta increases in length. It pushes the mature capsule and ruptures the calyptra and the covering sheaths, the perigynium and the perichaetium. As a result, the capsule emerges out of these protective sheaths.
(iii) Capsule - The mature capsule is spherical with yellow colour structure. It consists of a single layered sterile jacket enclosing spores and elaters. The spores are round ranges from 12- 30 mm in diameter. The spore wall made up of two layered, the outer thick exospore and an inner endospore. The capsule is enveloped by three protecting covering the calyptra, the perigynium and the perichaetium.
3. L. S. of Sporophyte of Pellia - Sporophyte of pellia represents foot, seta and capsule.
(1) Foot - It is conical. The sporophyte remains attached to the gametophyte with the help of foot. It is made up of parenchymatous.
(ii) Seta - The cells of seta arranged in deinite longitudinal rows. The cells of seta relatively small and the starch grains may not be present at maturity.
(iii) Capsule - It is a spherical structure two or more cell layered jacket. The cells of outer layer of jacket are radial with thickening bands and cell of inner layer is thin and semilunar thickening bands. The jacket encloses a mass of spores and elaters. Presence of basal elaterophore is the characteristic feature of pellia. It consists of 20 - 100 elongated elaters. Each elater has two spiral thickening bands.
4. L.S. of sporophyte of Anthoceros -
The sporophyte of anthoceros is an erect cylindrical structure consists of foot and a capsule.
(i) Foot - In L.S. of sporophyte shows basal bulbous part which is made up of parenchymatous cells. The foot absorb water and mineral nutrients food from the gametophyte for the developing sporophyte.
(ii) Capsule - Capsule presents various parts as given below-
(a) Capsule wall - It is made up of 4 - 6 layered parenchymatous cells. The outer most layer form epidermic is composed of vertically elongated cell. It is covered on outer side by a thick layer of cuticle. Stomata are present in epidermis with guard cells.
(b) Sporogenous Tissue - It extends like a cylinder a round the columella from the base to the tip of the capsule. The sporogenous tissue overarches the columella like a dome. The capsule matures in basipetal sequence and such differentiation of archesporium into spores and elaters.
The archesporium is single layered and is undifferentiated, but in the upper region the sporetetrad and pseudoelaters in regular alternate blocks. The elaters are simple or branched and are composed of 1- 4 cells of irregular shape. Elaters of Anthoceros are absence of thickening bands.
(c) Columella - It is located in the central region of capsule and extending almost to entire length. It is composed of 16 verticle rows with thick walled sterile tissue. Columella provides mechanical support to capsule. It also helps in spore dispersal. Sometimes under certain conditions the elongated cells of columella also function as water conducting tissue.