A Blue Scarlet Pimpernel

Nearly forty years ago, when I worked in the Agricultural Research Service, I visited a farm in Shropshire where I noticed the blue form of scarlet pimpernel Anagallis arvensis ssp. foemina growing in a field of onions, alongside the typical scarlet form. This beautiful blue variant is rather uncommon and restricted to central and southern England, so I never encountered it again when I moved to north-east England - until now. Last year I was given some seeds of A. arvensis ssp. foemina and this year they've flowered in our garden. The gentian-blue flowers are as exquisite as I remember them from that first encounter.

The scarlet form already grows in our garden. The plant is also known as poor-man's-weather-glass as the flowers close quickly when the sun is obscured by cloud - so they've been closed rather a lot this summer. They also close entirely in mid-afternoon every day, as regular as clockwork.

The other curious feature of these plants is their spherical seed capsule, known botanically as a pixidium, that opens by splitting around its circumference - click here to see one in action.

Magic of the Hemispheres

Remember those rotating globes of the world that used to be in every school classroom? I recall having a miniature version given to me as a Christmas present by parents who probably hoped it would sharpen up my performance in geography classes. The globe separated around its equator into two hemispheres, just like this scarlet pimpernel Anagallis arvensis seed capsule, which separates and releases a shower of seeds from within it you gently squeeze it. For the plant in flower, see http://cabinetofcuriosities-greenfingers.blogspot.com/search/label/Anagallis%20arvensis)

Botanically, this form of capsule is called a pyxidium - useful to remember if you've got an x to get rid of in a game of scrabble. Plantains (Plantago spp.) have a similar arrangement in their rows of minute capsules, although they're smaller and less aesthetically pleasing.

3 o'clock Closing Time

This scarlet pimpernel Anagallis arvensis plant was growing on the edge of some fields on the seashore at Low Newton in Northumberland. You can use this plant as a rough-and-ready clock because its flowers, which exhibit natural rhythmic sleep movements, always close up at around 3pm. in the afternoon (I took this photo at about 1pm.). It isn’t a very reliable time-piece though, as the flowers also tend to close if the sun clouds over and it begins to rain, so it’s a fair-weather clock. Quite a few plants have these natural flower closure mechanisms at different times of day – most notably Jack-go-to-bed-at-noon Tragopogon pratensis.In 1822 John Claudius Loudon, in his Encyclopedia of Gardening, listed 25 plant species with different flower closure times and suggested that they could be planted as a floral sun dial - which would be colourful but erratic.