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Re: cotyledons revisited


Ben:

>I looked in several books and found pictures of germinating Peperomia 
>Sagitaria Allium and Yucca (all monocots) All named the structure 
>connected with the seed and ending in the haustorium, the cotyledon. 
>I could not find a single picture naming it otherwise. Could you give 
>me the pages Joe were you did find it. 

I'm not sure just what point you are trying to make here.  In Plant 
Anatomy by Katherine Esau, second edition, 1965 in 726 pages of text 
and pictures the word haustoria is only mentioned once.  I quote: 
"Some plants develop highly specialized mechanisms of food absorption. 
Various cells of the embryo sac, and also the endosperm and the 
suspensor, may develop haustoria that penetrate into adjacent 
tissues."  I don't see what this has to do with cotyledons.

On page 726 there are several pictures of onion seeds showing embryo 
development.  One picture is a cross section of a fully developed seed 
and the cotyledon is CLEARLY labled "cotyledon" with an arrow pointing 
to the structure that is the cotyledon.  Nothing is labled 
"haustoria."

>Raven and others too gives good definitions: Cotyledons are the 
>structures that store food in dicots (like beans ) and absorbs food 
>in most monocots.  Just as I stated

This is something new to me.  I searched through Esau and didn't find 
anything that even comes close to saying anything like this.  

>Joe states that the first leaf is the cotyl as it is already 
>present in the embryo.  If one looks under the microscope in a 
>germinating hosta seed( as I did) no trace of a leaf can be found.

A germinating hosta seed doesn't have a leaf - it has a cotyledon!

Ben, would you please read Esau's Plant Anatomy, second edition and 
please show me the portions that support your point of view.  I've 
been searching hard to find evidence that says you are correct, but as 
hard as I try I can't find anything!

Also Ben, I understand you have some view about counting pods in 
hostas that was mentioned on this robin some time ago.  Can you 
explain?

Joe Halinar

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