Onion (Allium cepa) is a monocot with an emergent photosynthetic
cotyledon although the tip of the onion cotyledon remains within the
seed to absorb nutrients.
PROFDHW at AOL.COM wrote:
>> The probable reason for so much confusion about coconuts, aside from
> ignorance (meant in the sense of "uninformed") about plant structure in
> general, is that coconuts are monocots (mono- = one, -cot = cotyledon) and
> most discussions of cotyledons are broached from the dicot (di- = two)
> perspective. This probably relates to the fact that many (Most?) dicots have
> emergent cotyledons while few (if any; Ross? David H.?) monocots use their
> single seed leaf (the other name for a cotyledon) for anything other than as
> an absorptive interface between the endosperm and the growing part of the
> embryo. Emergent, photosynthetic cotyledons are much easier to point to in
> lab.
>> Even in dicots with hypogean (underground) cotyledons which remain inside the
> seed coat, such as the garden pea (_Pisum_ _sativum_), the cotyledons are
> easy to demonstrate. Try this with the monocot corn (_Zea_ _mays_).
>> Dave Williams
> (an old, botanical fire horse who salivates every time he hears words like
> "petiole" and "hypanthium")
>> Science Department
> Valencia Community College, East Campus
> 701 N. Econlockhatchee Trail
> Orlando, FL 32825
>profdhw at aol.com> 407-299-5000 x2443
