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Re: 2 for 1

  • Subject: Re: [iris-photos] 2 for 1
  • From: "David Ferguson" manzano57@msn.com
  • Date: Mon, 15 Sep 2003 10:12:28 -0600
  • Seal-send-time: Mon, 15 Sep 2003 10:12:28 -0600

This may not be totally relevant, but I thought it might be worth a mention.  I have often germinated seeds with twin embryos within one seed.  Sometimes I noticed and germinated them on purpose, watching them all the time.  Other times I discovered them after they germinated.  It appears that sometimes the two are identical twins and represent the same embryo having split.  Other times they are not identical and were either a split ovule pollinated by separate pollen, or they were separate ovules somehow connected from the start.  In other words they often were not identical.  Sometimes the twins are fused as if grafted, and sometimes there is no actual connection.  I once even germinated triplets from one Opuntia seed.  While I have not germinated that many Iris, and have not seen it happen, I see no reason why it couldn't.  So, in some cases, I suspect that the embryo just split at an early age (prior to or after germination?) and produced two fans, in which case they would be identical.  However, when the two fans are different, you may have twins!  I don't think I've ever seen a birth announcement for twin plants!
Another interesting thing I've observed occasionally (perhaps not really related?) is when an embryo develops with too many parts.  This is more evident in Gymnosperms and Dicots than in Monocots, but it happens in Monocots too. An example is an Ash tree that came up in the back yard when I was a kid in Loveland, Colorado.  It germinated with four cotyledons instead of two, and promptly started growing leaves in whorls of four instead of the usual pairs.  When we moved away, the tree was about 15 ft tall, and still doing it.  When I looked at it again in about 1996, it was still there, about 50 ft tall, and still doing it on all branches.  It is a very pretty and dense looking Ast tree!  Most plants revert to normal when very young, but some keep it up their entire lives.  In Monocots this seems to manifest in more leaves, more crowded on the stem, more flower parts, more loculs in the fruit, etc.  I've seen sedges with four or five "sides" instead of three, cattails with leaves in a triangular fan instead of flat, and so on. 

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