Bindweed or convolvulus is dreaded by gardeners. Its coiling grasping stems throttle and smother less aggressive plants. Plants of this genus have long roots. A tiny section of root left in the soil regrows vigorously. Alongside bindweed the RHS gardening website offers such gardeners’ nightmares as ‘couch grass, ground elder and Japanese knotgrass’ as ‘others you might like to read about’. Yet walking round the village I have been admiring the huge white trumpets of the larger species. If I had been walking along a Mediterranean lane I know I would be enjoying, rather than shuddering at their presence.
In this area we have 3 species of bindweed: field, hedge and large. (By the coast you also have sea bindweed.) Field bindweed has small white, pinkish or candy floss pink and white trumpet shaped flowers. Field bindweed often creeps along the ground and so is one of the few flowers which survive when our pavements’ verges are cut.
Hedge and large bindweed are very similar, with large white trumpet shaped flowers. These two species can be told apart by the difference in their flower bases. Large bindweed has huge overlapping brown-purplish bracteoles – leaf-like structures – at the base of the flowers, which almost hide the much smaller pale green sepals. The bracteoles of hedge bindweed don’t overlap, so the flowers’ sepals can be seen.
I mentioned that large bindweed, with its huge white trumpets made me feel like I was in the Mediterranean, I now discover I am not mistaken: large bindweed is in fact a Mediterranean plant that was brought to this country. This often happened as people started travelling: they brought back seeds or cuttings of plants they liked; as with large bindweed, the more vigorous escaped from their gardens or estates into the countryside.
Last time I wrote of how plants have evolved, with buttercups being early in the evolutionary stage with separate petals, and multiple female and male parts. Bindweed is an evolutionary stage further on. Looking closely, it is possible to see where what would have been 5 separate petals have fused, creating the funnel shape. (You could think there were 10 petals, 5 of the lines are creases remaining from where the flower folded in bud.)
Instead of the open flower of a buttercup, now insects have to enter a funnel to reach the nectar at the base of the plant. So the plant need not have so many female and male parts, as the chance of any one insect pollinating each is increased. Instead of the multiple male anthers of buttercups, convolvulus have just five. By looking at such a common – and unwanted(!) – flower, we can see the brilliance of evolution in front of our eyes.
To return to butterflies, from the post the one before last. The Big Butterfly count is on from now until Sunday 9 August. To take part, we are asked to choose a spot to watch and count and record the butterflies we see in a 15 minute period and enter this information on Butterfly Conservation’s website. A downloadable poster is provided to help with ID. I hope the description of the Big Five butterflies in my recent post helps too. Our results give Butterfly Conservation important information about how our butterflies are doing. As well as assisting conservation of butterflies, watching a local patch, whether in your garden or elsewhere, gives a good insight into how many insects are dependent on the nectar flowers provide. I will be unpopular for saying this – especially in my own family – but bindweed helps with this too!
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