Sunday, 21 April 2019

Goat's Beard and Bee flies

A few days ago (8 April to be precise) I was commenting on the phenomenon of nyctinasty. I had in mind those flowers that close at night, to open again in fine weather. It comes from the Greek nyctos, meaning night, and for years I had believed that the term applied only to plants such as the common lawn daisy, whose name of course is derived from 'day's eye'.  But what of plants which behave in the opposite manner?

I have in mind Goat's Beard, Tragopogon pratensis, a specimen of which has popped up in our front garden. One of its many other names is Jack-go-to-bed-at-noon because, just when the sun is at it brightest, the flowers close.

In our front garden I had been watching a Dark-edged Bee-fly, Bombylius major, as it delicately inserted its proboscis into the tubular flower of a Cowslip. Its actions were so reminiscent of a humming bird.

Bombylius major feeding at a cowslip in our front garden.
Stefen Hill, Daventry. 20 April, 2019
As I stepped back, trying not to disturb this remarkable but common insect, my attention was caught by the Goat's Beard. In the bright sun of this blisteringly hot day, just when pollinators would be about, its flowers were closed for business.

The flowers of this Goat's Beard were firmly closed at midday
Our garden at Stefen Hill, Daventry. 20 April, 2018

At ten am the following day the flowers were open again.

Open at ten a.m. but only to close a couple of hours later.

This, I felt, made no sense, yet after scouring my botany books and the internet I found no explanation for this seemingly illogical behaviour. Apparently the term nyctinasty not only covers the closing of flowers at night, but in the daytime too.

Tony White. E-mail:

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