Primitive plants of Melkote

Japanese fan fern:  Actiniopteris

The earth formed about 4.54 billion years ago .The geological time scale is divided into eras and periods. About 2000 million years ago the first cellular life appeared on earth. The first land plants appeared during Palaeozoic era. The end of this era called carboniferous period, that is about 250 million years ago (250 mya) witnessed flourishing growth of tree ferns, horsetails and club mosses. Triassic and Jurassic periods, the golden periods of dinosaurs (about 140 mya) saw extensive growth of cycads and conifers. These details are evident from the fossil records. The ferns, scientifically called pteridophytes, still exist on the earth.

Geological time scale

Generally pteridophytes are described as plants growing in moist, shady forests. Hence, one looks for them in thick rain forests, not in scrub jungles where there is less rain fall and moisture. Scrub jungles are characterised by bushes and small trees adapted for dry climate.

Lichens on bare rocks

 Melkote is an area covered by huge monoliths still undergoing weathering since a very long time. The soil is thin layered, rich in minerals but contains less humus in it. The area resembles more of semiarid conditions and hence has less humidity. Most parts of the hilly regions are still witnessing primary succession of xeric type.

Mosses succeeding lichens

Gradual and fairly predictable change in the species composition of a given area is called geological succession. During succession, vegetation in the given area changes. Succession that takes place in a very dry area leading to moderately normal growth of plants is called xerarch succession. In Melkote, it starts on a bare rock. The species that invade such a bare area are called pioneer species which are usually lichens (symbiotic association of algae and fungi). Lichens secrete acids to dissolve rock and increase soil content thus facilitating further weathering. This paves way for mosses (Bryophytes) such as Riccia, Funaria, etc. the bryophytes further corrode rocks, improve soil and are succeeded by tracheophytes that possess xylem and phloem. Pteridophytes, generally called ferns are the simplest tracheophytes. This is how we can witness quite a few numbers of ferns on the hills of Melkote area.

Selaginella

On our trek to “Gavikallu Gudda”, we saw Selaginella,Adiantum, Hemionitis (Arrow head fern) and Actiniopteris (Japanese fan fern).

Adiantum

Succession proceeds as the ferns pave way for larger seeded plants such as Cycas, Cantnthium, Dodonia, Tecoma, Withania, Wrightia, etc., which are adapted for dry conditions . These are sun loving plants forming a scrub jungle that we see today.

Hemionitis (Arrow head fern)

Since succession is a very slow process that takes thousands of years to change further, our life time is too short to judge whether this stage is the stable one having equilibrium with the environment. If so, this makes the climax community.

For a learner of life sciences, Melkote is a heaven having diversified life forms that describe on-going changes in the environment.

Geetha H