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Old 19-04-2006, 10:36 AM posted to sci.bio.botany
Dick Chambers
 
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Default Fruit and Placenta

I know, of course, that edible fruit has evolved by natural selection. The
sweet-tasting fleshy fruits attract animals, who eat the fruit, spit out the
seeds, and inadvertently sow the next generation of the plant. This
evolution process may have started, millions of years ago, with a
not-very-satisfying fruit, and natural selection has caused the evolution of
the fruit into the sweet and fleshy forms we know today. The tastier and the
fleshier the fruit, the better it will attract animals to spread the seed.

My question is:- Why did the prototype form of fruit ever exist in the
first place, many millions of years ago? Why did seeds ever have fleshy
fruit around them, however thinly and however bitter-tasting, from which the
evolution process could begin? Could the flesh of the fruit have been a
botanical form of placenta, separating the DNA of the mother plant from the
DNA of the seed? i.e. performing a similar function to that of the
placenta in the animal kingdom. Is there any evidence to support this
hypothesis? Does the flesh in (for example) the modern peach perform the
function of DNA-separation, in addition to its well-known function of
attracting an animal to eat it and spread the seed?

What function does the flesh of the berry have in Deadly Nightshade? As the
berries are poisonous, the plant does not rely on animals to spread the
seed. The flesh of the berry would therefore seem redundant, unless it also
has some other function, such as a botanical form of placenta.

Richard Chambers Leeds UK.