Bulb Log 46 2011

[Richard Green]

I am just picking up a point made by Ian’s lovely photo of the drop of water at the end of the crocus leaf.  I do not think this has condensed out of the air.  It is a phenomenon called "guttation" which is the exudation of water from specialised cells called "hydathodes" generally around the edges of leaves.  This occurs mainly at night when transpiration is much reduced and excess water vapour cannot escape from stomata on the leaf surface which close at night.  It is most prevalent when there is excess soil moisture from recent rain, and can easily be confused with condensation, and/or raindrops.  Overnight dew (especially on grass lawns) is frequently this exudation.

Guttation is probably also partly the cause of much of the silver on the Corydalis picture at the beginning of the Log.  It can be identified by looking closely at the leaves when drops can be seen exuding from exactly same points on every leaf.

It can also occur in household plants, which can drip from leaf ends after heavy watering !

[Maggi Young]

I think your explanation of guttation is probably correct for the crocus instance, Richard.... but for the silvered and jewelled corydalis I think it is more a case of preciptation collecting at those points, being natural "traps" for liquid.

The phenomenon is most marked after rain or heavy dew.

[Richard Green]

I am  at the thought of Ian crawling round in the dark checking this !

[Maggi Young]

Sssssh! I'll do my best to get  a photo! 

[Richard Green]

There is a splendid example of "guttation" on the front cover of December 2011 issue of The Plantsman which has just landed on my doormat. The Disporum leucanthum pictured shows droplets exuding from the tips of the petals - even the ones well within the flower.

[Maggi Young]

Unfortunately the budget in the Young household does not run to subscriptions to the Plantsman - that what comes of retiring with ill health at the age of 46 - so we'll have to take your word for it! Unless you could privately email us a photo, of course  

[David Nicholson]

Maggi, I'll see what I can do later today. If it's not good enough when you get it let me know and I'll try a scan.

[Maggi Young]

Maggi, I'll see what I can do later today. If it's not good enough when you get it let me know and I'll try a scan.

Thanks David, that's kind of you.