Acorns are not the only fruit…

When I visited my oak tree just a couple of weeks ago, I could see tiny acorn cups developing (see Summertime oaks).

However now it’s clear that these are never going to develop acorns – the stalks are starting to atrophy.

What has gone wrong?  I am told that, at around 30 years old, my tree is too young to be likely to produce acorns but why should this be?  After all, annual plants produce seeds after just a single year of growth.

It’s all a matter of prioritising limited resources – at this youthful age the tree is still growing and it would be a waste of energy to produce acorns when it is not capable of ensuring they will be large enough to be viable and to be widely dispersed (see Why trees?).  The tree’s principle job, after all, is to reproduce itself successfully and plants ‘choose’ how to partition their resources, to this end, all the time.  When you plant a potato in the garden, first of all it sprouts and produces a leafy plant.  Then, when the plant has enough leaf area, it will start to divert some of the sugars produced by photosynthesis to the roots to form the tubers which are the plant’s offspring.  Similarly, when water is limited a plant will produce roots, at the expense of above ground tissue, to ensure it can maintain an adequate water supply.   My oak tree is putting all its energy into growing bigger and stronger for now.  Plants, like animals, are masters of the biological trade off!