Each plant or group of plants has some phylogenetic significance in relation to evolution: Cycas, one of the few living members of gymnosperms, is called the ‘relic of past’. Can you establish a phylogenetic relationship of Cycas with any other group of plants that justifies the above statement?

Answers (1)

Answer: Cycas is the only living species in the family Cycadaceae. All other species of the Cycadaceae family are extinct, as of now. Cycas plant is often considered as the living fossil and the plant of the Old World; because it is found only at those places where some of the oldest rocks in the world are found. Because of these reasons, Cycas is also known as the ‘relic of the past’.

Besides that, Cycas resembles more with Pteridophytes than any Gymnosperms. This proves a phylogenetic relationship between Pteridophytes and Gymnosperms.

Some features of Cycas which prove this are as follows: -

  • In Cycas, the seeds are shed when the embryo is still developing or mature. In gymnosperms, seeds are shed solely when the embryo is mature.
  • The megasporophylls look like a leaf.
  • Even though the pollen tubes are present, the male gametes are flagellate.
  • Leaf base is persistent in nature.
  • Circinate ptyxis; which is similar as in Pteridophytes.

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