Hepaticopsida: Character (Honours )

 GENERAL CHARACTERISTICS

1. The vegetative plant body is gametophytic and the gametophyte is dorsiventral and either thalloid (i.e. thallus like) or foliose (i.e. bearing a leafy axis).

2.In foliose members, the leaves are arranged on the axis either in two or three rows.

3. A well-marked midrib is almost absent in the leaves.

4. Photosynthetic cells of the gametophyte contain numerous chloroplasts, which lack pyrenoids. 

5. One to many refractive oil bodies are usually present in all the chlorophyll-containing cells.

6. The sex organs are in the form of well-developed antheridia and archegonia.

7. Each sex organ develops from a single initial cell.

8. Fertilization results in the formation of a sporogonium. 

9. The sporogonium is usually devoid of chlorophyll-containing cells.

10. Stomata are also absent in sporogonium.

11. The sporogonium is either simple (e.g. Riccia), or differentiated into foot, seta and capsule (e.g., Marchantia). In some members, it is made of only foot and capsule with no seta.

12. The archesporium (the tissue that gives rise to the spore mother cells) is endothecial in origin. 

13. The sporogenous tissue of the capsule gives rise to fertile spore mother cells and sterile elaters (e.g. Marchantia). In a few genera, the elaters are absent (e.g. Riccia).

14. In most of the genera, the elaters are unicellular structures with spiral thickenings in their walls.

15. Columella is absent in the capsule of the sporogonium. 

16. The capsule generally remains covered by a well-developed jacket. On being dry, the jacket ruptures releasing the spores.