Jan 2 2018
09:02 am

On our icicle hike yesterday we noticed the rhododendron leaves drooping and curling tightly. This is their protection from freezing and thawing water within the leaf. Water crystalizes as is freezes and can rip apart the inner structure of cells if something doesn't protect the plant. Conifers have resin that acts as antifreeze but what is going on with rhododendron?


"Rhododendron leaves respond to the cold, first by drooping and then by curling up - this is called thermonasty. When temperatures are above freezing, typical rhododendron leaves will be flat and oriented horizontally to the ground (presumably to collect as much sunlight as possible). As temperatures drop, the leaves follow suit. When temperatures fall below freezing, the leaves start to droop but remain flat. At 25 F the leaves start to curl and by 20 F they are as tightly curled as they can get."

From what I can tell...

we don't actually know what the mechanism is that produces the movement in Rhododendron.


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