BSc 1st Year Botany Bryophytes Sample Model Practice Question Answer Papers

Q.3. List the salient features of important groups of Bryophytes, Characteristic feature of important groups of Bryophytes.

Ans.3. Class Hepaticopsida or Hepaticeae

The class hepaticopsida or hepaticeae includes about 280 genera and 9500 species. Hepaticeae is the Latin word meaning liver and the members of hepaticopsida therefore popularly called as Liverworts.

The salient features of the class hepaticopsida are as follows:

1. The vegetative plant body or gametophyte is usually dorsiventral and is either a thallus (thallose) or a leafy axis (foliose).
2. The gametophyte is internally either simple or made up of many tissues, but the photosynthetic cells always contain numerous chloroplasts without pyrenoids.
3. The sex organs are usually formed directly from the dorsal superficial cells of the thallus, except when terminal in position.
4. The sporogonium has little or no chlorophyllous tissue and lacks stoma.
5. The sporogonium may be simple (as in Riccia) or may be differentiated into foot, seta and capsule (as in Marchantia).
6. The capsule lacks a sterile region, the columella.
7. There is a distinct alternation of generation.
8. The class hepaticae consists of four orders viz—Spherocarpales, Marchantiales, Jungermanniales and Calobryales according to the latest classification.

Anthoceropsida—Anthocerotae

Anthocerotae is a small group of plants, including nearly 6 genera and 332 species like Anthoceros, Notothylus, etc. The plants of this group may be characterized by the following features:

1. The plants of this group are moist and shade loving.
2. The gametophytic plant body is a dorsiventral lobed thallus without any internal differentiation of tissues.
3. The plant body is attached to soil only by means of smooth walled rhizoids.
4. Tuberculated rhizoids and scales are absent.
5. There are no air chamber or air pores.
6. Each cell of the thallus usually has single large chloroplast with a conspicuous pyrenoid. (BSc 1st Year Botany Bryophytes Sample Model Practice Question Answer Papers)
7. The thallus bears sex organs that are endogenous in origin and sunken in the thallus. (BSc 1st Year Botany Bryophytes Sample Model Practice Question Answer Papers)
8. The antheridia lie single or in groups in closed cavities.
9. The archegonium are sunk in the tissues of the thallus on the dorsal side.
10. The sporophyte or sporogonium consists of a bulbous foot, and long cylindrical capsule. (BSc 1st Year Botany Bryophytes Sample Model Practice Question Answer Papers)
11. Presence of central columella which is arched over by a dome shaped archesporium in sporophyte.
12. The archesporium is sporophytic.

Class Bryopsida

The group Bryopsida or Musci is the largest group of Bryophytes including about 660 genera and 1500 species of mosses.

The characteristic features of mosses are follows:

1. Mosses are cosmopolitan in distribution.
2. These mosses thrive in abundance and form velvet like matting on the soil. Some occur on soil e.g., Funaria, some may be aquatic e.g., Sphagnum, some may be lithophytic e.g., Andrea, some may be sporophytic e.g., Munium.
3. The gametophytic plant body of mosses is differentiated into rhizoid ‘stem’ and ‘leaves’.
4. The rhizoids are multicellular possessing oblique septa.
5. Leaves are green, papery and spirally arranged on stem.
6. Internally ‘stem’ is differentiated into central conducting stand called medulla and the peripheral storage region, cortex and outermost epidermal layer.
7. ‘Leaves’ possess a distinct midrib except Sphagnum.
8. Sex organs are stalked.
9. Fertilization ends the gametophytic generation.
10. The sporophyte of Mosses is more elaborated and complex and shows high degree of specialization.
11. Absence of elaters.
12. Archesporium develops from inner layers of amphithecium.
13. Presence of columella.
14. Dehiscence of capsule takes place by lid formation.
15. The spores are formed by the reduction division of spore mother cells. These germinate and form filamentous branched protonema, which produces buds. The buds later develop into adult plants.
16. There is a distinct alternation of generation.

BSc 1st Year Botany Bryophytes Sample Model Practice Question Answer Papers

BSc 1st Year Botany Bryophytes Sample Model Practice Question Answer Papers

BSc 1st Year Sample Model Practice Mock Test Question Answer Papers