[opus (OP)]

What's the difference between a seed and a spore?

[WylieE]

Hi Opus,

  I think this is one of those pairs of words that are very commonly confused.

Spores come from non-flowering plants (mosses and ferns) and fungi.   Seeds come from flowering plants.  Seeds come from the ovules of the flower. 


http://www.ou.edu/cas/botany-micro/ben/ben122.html

A spore consists of a single cell and contains no preformed embryonic parts. In contrast, a seed (typically) consists of hundreds or thousands of cells and contains stored food (the endosperm) and an embryo. Moreover, spores and seeds differ in what they give rise to. A fern spore gives rise to the prothallus of the gametophyte generation; a seed, to the baby plant of the new sporophyte generation.

What the last line means is that spores are haploid and when these spores divide they give rise to haploid cells or the reproductive generation of the organism- in the case of the ferns the tiny prothallus that then through sexual reproduction produces the zygote that creates the diploid sporophyte generation- the fern that you see.

 Seeds are formed from the union of two haploid cells (the pollen and the ovule) and the cells of the embryo divide to give rise directly to the diploid (or more) sporophyte generation of the plant. 

[Carol-A]

I think that spores arise from Asexual reproduction and seeds from sexual reproduction.

[opus (OP)]

Thankyou CarolA and wylieE for your replies. I knew about the asexual/sexual side of spore/seed production, but wondered about how the finished articles compared to each other. I now know that this is to do with cell number, and whether there is an embryo and food store.
                I have looked at fern spores in a sporangium and thought I was looking at several diploid bodies inside. Is this right?

[WylieE]

Hi Opus!

  Well, on a fern if you are looking at the spores inside a sporangium they would be haploid cells.  The sporangium itself and the "leaf" it was on would be diploid.  The spores inside are haploid they get distributed and if they find a nice moist place to land will grow into a prothallus- a tiny little structure.  Then they produce sperm and eggs and the fertilized egg (zygote) is now diploid and this grows into the diploid fern.  When it is time to reproduce the fern goes through meiosis to produce haploid spores and the whole thing start again- here's a picture - and I know I've seen a good animation of this, but I can't find it just now, I'll keep looking.

Colleen

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[WylieE]

I don't know if this is the good animation or not - I don't have flash on this computer so I can't tell: I hope it's good!

http://academic.kellogg.cc.mi.us/herbrandsonc/bio111/animations/0124.swf

[opus (OP)]

Hi Colleen- that animation is terrifc- really explains the whole complicated life cycle of these amazing ferns. Thankyou very much for posting it.  Must search that site for lichen info too!