I’m not a very tidy gardener and one of the joys of this is waiting to see how many and what colour of foxgloves will spring up in both my allotment and back garden. As a pioneer species, they are quick to occupy any open ground in the garden. The slugs have ensured that not much else is thriving in the allotment at the moment but at least the bees are happy!
‘Foxglove’ sounds like a name conjured up by Beatrix Potter but it goes back well before this. In The Englishman’s Flora, Geoffrey Grigson talks about the plant’s long association with fairies and magic because of its poisonous leaves. One explanation given for the name is that fairies gave foxes the flowers to wear as gloves to allow them to raid hen houses without discovery! The Latin name, Digitalis, was coined by German physician and botanist Leonhart Fuchs in his 1542 herbal, De Historia Stirpium. This also alludes to the finger-like shape of the flowers, particularly before they open.
Foxgloves rely on bees to carry pollen from one flower to the next and, unlike many orchids (see Orchids and their pollinators) they do provide a nectar reward for the insects at the base of the flower. Bees land on the flower’s broad lip then follow an attractive crazy-paving style pathway towards the back of the tunnel-shaped flower.
The guard hairs at the mouth of the flower deter smaller insects because, with the anthers and stigma on the roof of the flower, only larger insects will be able to carry out pollen transfer.
Flower just about to open, with bottom section cut away to show immature stigma and anthers full of pollen
When the anthers have burst open, releasing their pollen, the bee will pick up some of that pollen as it brushes past and will then deposit this on the stigma of the next flower it visits.
Inside fully open flower – anthers have split open and shed their pollen
The flowers are carried in a long spike. Those at the base open first, giving the spike its elegant, tapering shape – these will be well on their way to setting seed before the flowers at the top of the spike open. This strategy gives the plants a long period in which some flowers are available for pollination – useful, given the chances of some cold, wet British summer weather in which insects are less active. It also means that the last flowers to open will still tower above other rapidly-growing summer vegetation – vital for a pioneer species.
Most people are warned off foxgloves as children because they are poisonous – both flowers and leaves contain chemicals known as cardiac glycosides which, when converted to aglycones during digestion, affect the heart muscles. They reduce heart rate to such an extent that a heart attack can occur as the heart struggles to deliver enough oxygen to the brain. Maybe the best known case of foxglove poisoning is when Lady Westholme injects Mrs Boynton with the drug digitoxin in Agatha Cristie’s Appointment with Death.
However cardiac glycosides, such as digitoxin, are also historically-important heart medications when given in the correct dose. As long ago as 1785 William Withering wrote in his Account of the Foxglove about how foxlove could be used both to treat heart problems and as a diuretic. Slowing the heart rate just a little can allow it to fill and empty properly and make the kidneys more efficient because of their increased blood supply. Both Digitoxin and Digoxin, extracted from Digitalis lantana, have been used to treat abnormal heart rhythms – my own father-in-law took Digoxin for a number of years. Getting the dose right is critical, though, as too much can have quite unwonted consequences. Beta blockers and calcium channel blockers are more often used to control heart rate nowadays.