Handle with care the ‘aggressive’ plants
Understanding why so many of our common or garden plants have defence mechanisms is one thing but being on the receiving end is an entirely different matter, as I rediscovered quite recently. If you have a collection of roses to deadhead and the sun is blazing hot overhead as it has been of late, it`s natural to discard some of the protective clothing, but bare arms and shorts render it difficult to emerge from the task unscathed. I found solace in the fact that some of those thorns would have pierced any garment.
Plants are stationary, a sitting target, therefore need some form of protective device to ward off the nibblers, sap suckers and intruders of the animal kingdom. So, roses develop thorns as do cacti, berberis, pyracantha, Crataegus, and a whole lot more that we approach with caution when pruning or moving. We grow them for their beauty but a more practical use springs to mind. Their aggressive nature makes them ideal protectors.
The mechanical injury inflicted by these examples is immediate and painful but there are other plants we handle whose contact can cause general discomfort.
The rough hairs of borage (Borago) and lungwort (pulmonaria) even the finer hairs of mullein (Verbascum) are best avoided. Contact with some plants e.g. stinging nettles (Urtica) and cuckoo pint (arum) result in mechanical and chemical injury.
There are more than 100 plants capable of an allergenic effect but not to all gardeners.
My bete noire is Primula obconica which is grown as an indoor plant alongside the harmless cyclamen, calceolaria, cineraria and schizanthus for winter colour. It is so irresistible in pink, red and white but leaf contact with the skin brings an instant, painful rash.
Plant sap is also a common irritant that at the least is downright unpleasant. The Pasque flower (Anemone pulsatilla), greater celandine (Chelidonium majus), also clematis and euphorbia species, should all be approached with care.
Painful though these plants are, the photosensitisers are a group that should really be avoided. They contain furocoumarins which, in contact with the skin, cause a sensitivity to light. Cow parsley (Anthriscus), rue (Ruta) and giant hogweed (Heracleum) are amongst the worst offenders.
Best advice is to wear protective gear when handling these difficult plants.