Scutellum in corn not coconuts

David Starrett dstarret at BIOLOGY.SEMO.EDU
Fri Aug 13 19:33:07 EST 1999


>	My understanding about the difference between monocots and dicots
>is that dicots absorb the endosperm during embryo formation/maturation to
>form large cotyledons  and monocots absorb the endosperm via their single
>cotyledon during seed germination.  The scutellum is the term for the
>specialized absorbtive cotyledon found in grasses and is not used for other
>monocots.
>	Simpson and Ogorzaly (Economic Botany-Plants in our World, 2nd
>Edition, pages 136-138)  state "The [coconut] fruit is formed from a flower
>with 3 carpels (each represented by an 'eye' of the coconut), only one of
>which develops.  The mature fruit contains one seed, the largest known. The
>embryo itself is small and located near the stem end.  Initially the
>endosperm is a liquid containing free nuclei.  This liquid, called coconut
>water or coconut milk, is drunk from green coconuts in many tropical
>countries.  As the endosperm matures, cell walls form around the nuclei,
>and the endosperm solidifies into an oil-rich layer of coconut "meat"
>inside the seed coat.  It is the solidified endosperm that we eat...
>	If mature coconuts are not used or harmed, the embryo can germinate
>within the coconut since there is no dormancy period.  The germinating
>seedling eventually extends the tip of the cotyledon  through one of the
>eyes.  The base of the embryo swells into an absorbing organ that
>eventually fills the entire cavity of the coconut as it digests the
>endosperm.  The swollen organ, called a coconut apple, can also be eaten. "
>
>	I am not sure that  Simpson and Ogorzaly have correctly identified
>the coconut apple as being part of the embryo proper.  It may actually be
>the cotyledon which swells during germination and begins to absorb the
>endosperm.
>
>	Bowes (A color atlas of plant structure, page 148) states "In palms
>the cotyledon often enlarges greatly and becomes haustorial..."
>
>	In either case the cotyledon of coconuts is very small until after
>seed germination.  I hope that this is useful.

Tyhanks for these instights.  So, how does the meat get so evenly distributed?


Dave


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