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Botany: what is the evolutionary significance of losing a cotyledon?

  1. Dec 5, 2005 #1
    Hey there,

    I was reading up on angiosperms, and one of the possible evolutionary relationships that showed up were ancestors that originally had 2 cotyledons, and the lost of one later on rose to the arisal of monocots.

    I suppose this might be a really tough question, but what would be the benefit for a plant to start with having one cotyledon as opposed to two?

    Or maybe it'd be better to ask: what kind of environment would be better for a germinating seedling that has only one cotyledon?
  2. jcsd
  3. Dec 5, 2005 #2


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    That's interesting, I had not heard of that relationship before. I am curious where did you read that?
    Can't say I know of any benefits of having one seed leave over two.
    Modern monocots and dicots do have very distinctive characteristics: monocot(e.g. major leaf veins parallel, flower parts in multiples of three, stem-vascular-bundles scattered, pollen with a single pore...) dicot [e.g. major leaf veins reticulated (netted), flower parts in multiples of four or five, stem-vascular-bundles in a ring, pollen with 3 pores]. Those are just a few morphological differences (reference). Scientists believe the monocot-dicot divergence from a common ancestor, occured about 200 MYA (million years ago). That would be sufficient time to evolved all those differences we see today.
    I don't know what environments would be more advantangeous to monocots. Both mono and dicots prefer warm, loose friable topsoil to enhance germination.
    Last edited: Dec 5, 2005
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