Adult Common Blue butterflies and their caterpillars rely on Birds-foot Trefoil for food
Nature on our doorsteps: Tumbling over roadside verges
Rosaleen Dwyer is the County Heritage Officer at South Dublin County Council – every week she gives us an insight into the natural heritage around us and the beautiful biodiversity of the plants and creatures
The unusually named Bird’s-foot Trefoil is in full bloom at the moment.
This native wildflower is a member of the pea family of plants.
Wherever the soil suits it, it can grow widely along roadways and in flowering meadows.
It can often be seen tumbling over the kerbs of roadside verges, where it forms a mass of yellow flowers.
Its name comes from the appearance of the plant’s seed pods.
Each flowering stem holds between two to seven bright yellow pea-like flowers at its tip.
When these flowers are pollinated, long thin seed pods are formed which turn black when the seeds are mature.
The arrangement and colour of the slender pods gives the plant its name of ‘bird’s-foot’, because they look like the toes of a bird radiating outwards from a central point, like a claw.
Although it is referred to as being ‘trefoil’ or three-leaved, the stem in fact holds 5 little leaflets.
The arrangement of its long thin seed pods give the plant its ‘birds-foot’ name
The plant is low-growing, but it can reach to 30cm in meadows where plants are allowed to grow tall.
If the meadow is cut back, Birds-foot trefoil can revert right back to being low-growing once again.
Bird’s-foot Trefoil is rich in nectar and so it attracts a range of insects.
Butterflies can delicately probe deep into the flower with their long tongues, while bumblebees must force their way into the flower.
This makes bees more useful pollinators than butterflies, as they become covered in pollen as they push in and out of different flowers.
The Common Blue butterfly is particularly associated with this plant.
The adults sip the flower’s rich nectar while the leaves are the main food plant for its caterpillars. This makes Bird’s-foot Trefoil a very important ‘one-stop-shop’ for this butterfly species.
While feeding, the Common Blue absorb substances called flavonoids from the plant.
These substances enhance the intensity of the butterfly’s colours, particularly in the females.
This helps to make them more noticeable to a passing male which, of course, is an important advantage during breeding season.
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