Question

1-Describe the key evolutionary innovations that are associated with ferns. 100 marks

2- Make brief notes on any two of the following: a) Fabaceae b) Carnivorous plants c) Asteraceae (the daisy family) 100 marks

Answer 1

(1) - ferns were originated almost 430 mya in devonian. Ferns have many evolutionary innovation which make them very successful for study of plant evolution. Some innovation are presence of underground rhizome stems which form branched underground network, which remain for many years even after the falling of leaves. Other modification is circinate vernation which are tightly coiled for the protection of meristem. Presence of two different types leaves and sporangia are other modification which connect them with the evolution of other seed plants.

(2) - Fabaceae - this family is also known as pea family. There are 600 genera and 1200 species of this family. Plant body may be herbs, shrubs and trees, mostly climbers with alternate simple or compound leaves, leaf base may be pulvinate. Branched tap root system with bacterial nodules. Racemose inflorescence, pedicellate, complete pentamerous flowers. Seed are non endospermic and pollination by bees. Sub family are caesalpinioidae, mimosoidae and papilionaceae.

Carnivorous plants - such plants are generally present in soil with poor nutrient level. These plants depends on insects for nitrogen supplement. These plants attracted to insects due colour and scent. Enzymes helps in digestion of insects and internal structure absorption of amino acids. Pitcher plants have specific mechanism for trapping insects.