Trees loosing their leaves

[Hymie]

I have recently returned from the USA, driving around Texas and the neighbouring States. They were enjoying slightly warmer than normal temperatures for the time of year, with daytime highs over 25ºC with bright sunshine, and the night-time lows, no less than 10ºC (typically 15ºC).

Even so, under these conditions the leaves of the deciduous trees had changed colour and were showing all the signs of autumn (fall), perhaps a few weeks later than that seen in the UK.

Given that in a UK summer, 25ºC daytime and 10ºC night-time temperatures might be quite normal – why would a deciduous tree shed its leaves under these conditions?

[theprof]

Here's the latest view Hymie:

http://www.cambridge-...dump-their-leaves.htm

[theprof]

I would add that I know Brian very well indeed and I consider his views very plausible.

[wildwood]

Would this explain why broadleaved so-called evergreens like rhodos have toxic leaves?

[Hymie]

The answer given in the link posted by Eddie51 does not stand up to analysis – since a tree growing close to a river bank would have a continuous supply of water – and so would never shed its leaves.

If theprof’s link answer is correct – why do all trees excrete their waste at the same time, when the conditions for continued leaf photosynthesis are good throughout the year?

[ann_h]

My guess is this -
All deciduous trees need a rest period. They do this during the coolest part of the year. Texan trees are used to Texas, not Telford. Therefore they think 10C is bloody nippy, so for them it's autumn and time to shed.

[Hymie]

Well, out of the three answers offered – I reckon ann-h’s answer is the most logical.

[Avatar]

'losing' their leaves.

HTH HAND