Category Archives: biology

Why do leaves of most plants curl when it’s cold?

Last night was the coldest night so far this winter. It was 24f this morning. When the temperatures are this low many plants have the unusual response of curling their leaves.

This is known as a thermotropic response. There are many theories to why some plants do this: 1) Photo inhibition to reduce winter damage from radiation, 2) heat balance theory to maintain temperature, 3) freezing damage theory to prevent damage from rapid thawing after freezing, 4) mechanical theory to prevent damage to the leaf, and 5) desiccation theory to prevent the leaf from drying out are all theories as to why leaves curl in cold weather.

So many theories!

Some plants in my garden which commonly do this are:



Vinca major




The chain link fence which runs around the entire half-acre was planted by the previous owner with wintercreeper and is now covered and trimmed to resemble a hedge. The previous owner, who lived in the house for thirty years, did this many years ago and I thank her.

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Filed under biology, Plants, Seasonal Maintenance

Roots and things you find underground.

As I was dividing overgrow plants it reminded of some of the unusual parts of plants you find underground.

Pachysandra and stolons.


Stolons are stems which grow at the soil surface or just below ground. Plants use these to grow into large colonies.

Root-tubers of daylilies.


A tuberous root or storage root, is a modified lateral root, enlarged to function as a storage organ.

Cleistogamous flowers of violets


Cleistogamous flowers are self-pollinated flowers that do not open and lack petals. They never open and go straight to seed production. This clump of common violet has about 20 or so at ground level. This must explain why they multiply by seed so fast?

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Filed under biology