Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: paul.fr on 01/08/2007 22:07:47
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The cup must serve a purpose, but what? And, why did this seed and cup combo evolve?
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I'm trying to find an interesting angle on this, but failing I'm afraid! Not because it’s not an interesting question, but perhaps because it’s not an interesting answer! I’ll briefly warble on a bit about closely associated things though……
It's just the method that has so far evolved for their seed dispersal system. Oaks are a “climax species” (although this term is becoming outmoded). There are two basic genres of trees - pioneers, such as birch, which are relatively short-lived species and which produce small seeds in vast quantities, and that rapidly move into an area - and climax species, which are the species that dominate after the period of succession. However, the system is cyclical, and so you don't go from birch to oak and then stop, therefore there is no end, or "climax". However, this climax group tend to be long lived, and have very large seeds that require a lot of energy to produce. They also produce far less than the pioneers. The acorns grow in the cupule, and take from 6 to 20 (ish) months to mature before falling to the ground. This is the first step of dispersal. The second step relies on the intervention of animals, such as jays and squirrels to put the acorns somewhere safe as a food, but will then not use them all, which will then sprout if in an appropriate place.
It could be argued that this is a similar system to other trees, only the shell of the nut (the cupule) is only partially covering the seed (the acorn).
Sorry it’s a bit rambly – does it answer you question though?
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Sorry it’s a bit rambly – does it answer you question though?
It does, thanks. I always loved the way they look.