Cold weather in South Florida last night!

[susiep]

Gwen, are you talking about the leaves (mesophelial collapse) wilting and getting kind of translucent? Now I know what it is called! I saw that on some plants I didn't bring in on that earlier snap. I think the wind made it worse.

[Ray]

Mesophyll collapse is not usually connected with cold. Desiccation, insect damage (particularly mites), and the like are more common.

On the other hand, if the water in the cells actually freezes, the expanding I crystals can disrupt the cell membranes, causing death and collapse that looks like it.

On a positive note, due to the freezing-point depression brought about by dissolved minerals, the water inside the cells has to be below 32°F to freeze, which is why you see farmers continuously spraying water on crops when the temp is supposed to dip. As long as there are two phases present - solid (ice) and liquid - the temperature won't drop below 32°.

[Gwenchanter]

Susie actually what it looked like was a brownish "valley" in the middle of an otherwise healthy leaf where the cells collapsed. If the whole leaf is wilting I think that must be something else. I'm not 100% sure what caused it but I guessed it was the cold.