6 April 2025
Coltsfoot (Tussilago farfara) has been blooming since final month however after I visited Schenley Park on Friday beneath overcast skies and threatening rain, all of the flowers had been slammed shut.
Many daisy-like flowers akin to coltsfoot reply to decrease mild ranges at nightfall by closing their petals, then opening them as mild will increase after daybreak. It’s a every day train.
Their motion is non-directional with respect to the stimulus — i.e. the petals will not be flinching away — and has nothing to do with development of the plant so it’s a nastic motion. When it happens in response to decrease mild ranges it’s referred to as nyctinasty.
Nyctinasty from Greek: nyct = evening + nastos = pressed collectively.
Within the morning the petals begin to open once more.
After most are open you may see that flowers in shadow unfurl a bit later.
Watch as daisies and speedwell open and shut in response to mild.
Day by day the petals get a exercise.
