Ivy – ‘The Last Fuel Until Spring’
Out walking on a glorious sunny autumn day, I stop to consult the map and am immediately aware of the musical hum of insects. Putting down my map and rucksack, I go and investigate…. There is an old stone wall completely covered in Ivy, where all manner of bees, wasps and hoverflies are indulging in a feeding frenzy - everyone has been invited to the banquet!
Ivy (Hedera helix) is the last of our native flora to come into flower (September - November) and is therefore a valuable source of nectar and pollen for both over-wintering honeybee colonies and hibernating Queen bumblebees and wasps. If it were a petrol station it would have a large sign on the forecourt advertising “Last Fuel Until Spring!”
Ivy is readily identified with its 3-5 lobed leaves, carpeting the ground or climbing any suitable tree, rock or man-made structure. The stems attach themselves by white adhesive adventitious roots secreting glue-like lignin, looking much like the legs of a millipede.
However, look closely and you will see that Ivy produces two sorts of shoots that are so different to each other they have sometimes been mistaken as coming from different species. The juvenile shoots produce the distinctly ivy-like leaves we all recognise. In contrast, the adult flowering-shoots have diamond or oval shaped leaves, which lack the adventitious roots but produce small yellow-green flowers.
Nectar is secreted from the flower’s entire upper surface, from which a single stigma protrudes much like a wick of a candle. The surrounding five pollen-laden stamens and five small yellow-green petals are soon shed, giving the flower the appearance of a “99” ice cream. The nectar-secreting disc allows any number of insect species to visit – it is not a specialised flower, such as Foxgloves which require long-tongued bumblebees, or Honeysuckle which is visited by long-tongued Moths for pollination.
Ivy is not just a food source for autumnal foraging insects, but the purpleblack berries are a late winter source of food for birds and come spring the foliage is a perfect place for smaller birds to nest.
Many myths about the plant abound, and despite its smothering habit, it is not even a partial parasite and manufactures all its own nourishment in the same manner as other green photosynthetic plants. Finally, English Heritage, becoming concerned about Ivy growing on historic houses, commissioned Oxford University to investigate. The findings are good news for Ivy; it keeps buildings warmer in the winter and cooler in the summer, and protects properties from frost, salt and pollution. So provided Ivy avoids the gutters and roof space, it is a welcome household companion, which is also good news for nature.