The Fascinating World of Liverworts: A Closer Look

There are about 6500 species of liver worts. They are called ‘liver worts’ because some liver worts have an outline that resembles a liver, and thus they were thought to be useful treating liver ailments. The ending word means ‘herb’. Liverworts are small, generally inconspicuous and are restricted to damp environment. They are very common in the hills where they grow attached to the bark of trees, and on rocks in plains they are found during the rainy season growing on damp soil or on old walls.

Their body form is often a flattened, lobed and leaf like called thallus. The thallus is many celled thick, green, dorsoventral and dichotomously branched e.g. Riccia and Marchantia, from the ventral side of the thallus, lower epidermis give rise to a large number of colorless and unicellular rhizoids. The functions of rhizoids are anchorage and absorption of water and salts. Thin leaf-like scales also occur on the underside of the thallus. Other liverworts have a leafy appearance rather than a lobed thallus and superficially resemble mosses.

Reproduction: Liverworts reproduce both asexually and sexually.

Asexual reproduction: it takes place by vegetative method and by gemmae. The vegetative multiplication takes place by apical growth and branching and by progressive death of the older parts of the thallus. The other way that liverworts reproduce asexually is by forming balls of tissue called gemmae (sing: gemma), which are borne in a saucer- shaped structure the gemma cup directly on the liverworts thallus. When dispersed by rain or small animals, gemma grows in a suitable place into a new liverwort thallus.

Sexual Reproduction: The sex organs of liverworts e.g. Marchantia, are borne on erect branches on the same or different plants: The male branch is called antheridiophore. It consists of stalk and star shaped disc like receptacle. It has many antheridia. At maturity antheridium ruptures and biflagellate antherozoids are liberated In a drop of water.

The, female branch is called archegoniophore. The receptacle is divided into rays. It bears archegonia (ar-keh-gonia). Each archegonium has a long, narrow neck and a swollen venter with an ovum (egg).

Fertilization takes place in water farming a diploid zygote (2n). The zygote develops into a sporophyte. A fully developed sporophyte consists of a foot, a stalk or seta and a terminal capsule. Spores are produced in the capsule due to meiotic-division. The spores after liberation are dispersed and carried away by the wind. Each spore under suitable conditions germinates forming a gametophytic thallus.

Marchantia thallus 

Thallus with gemma cup

Structure that bear archegonia 

Structures that bear antheridia