Le Lierre - Ivy

The ancient romanised gauls in pronouncing the climbing vine ille hedera - 'the ivy' in Latin, contracted it to l'hedera and so it became lierre. But then that word needed a le, so we have le lierre. The English word 'ivy' remains much as the Anglo-saxons used it. It grows throughout Europe and it is an important and underrated constituent of the ecology of our woodlands. Though many think it is a parasite of trees, it is not. Its climbing stems hang on to bark and stones with hundreds of tiny rootlets, which are only holdfasts. The stems that produce the rootlets grow away from the light so that they squeeze between tiles and loose bark, prising them apart, and causing harm. If the amount of growth is too much it can cause the downfall of a tree. The evergreen leaves shade out those of the tree, which weakens the tree, and the weight brings it down. But this growth is excellent cover for the nests of birds. The leaves themselves, always turn towards the light. They vary in shape according to their position on the plant. Those on the ground and on tightly adherent climbing stems are star shaped. Those at the top of the growth and on the free falling flowering stems are rhomboidal. I cannot think of any reason for this variation, but it is a not unique feature. It is particularly in the time of its flowering and fruiting that makes this plant so ecologically valuable. It flowers late, in October. The tight bundles of flowers produce an immense supply of nectar. Large numbers of flies and bees come to feed, the slightly nauseous smell helping to attract. The Holly Blue butterfly caterpillar, in the second stage of its annual cycle, eats the flowers. The fruits ripen in February and March. At this very early season of scarcity they are welcome food for blackbirds and thrushes, at a time when insects are dormant and scarce. But in this is another question. All parts of the plant are poisonous to the majority of animals. Some people develop serious rashes if they scratch themselves against ivy, especially in full sun, and can develop a serious recurrent skin disorder (rather as happens with the unrelated American poison ivy). The poison is a soapy chemical called a saponin. If the leaves are macerated in water, the mixture foams up as though soap has been used. This saponin will damage the lining of the gut and will break down the red corpuscles of the blood. In winter the cold temperatures promote an increase in the sugar level of the berries. This helps to protect the berries against frost. I theorise, but could it be that after a severe winter the birds can swallow the berries because the poison is reduced and converted to sugar? I do not know. Ivy berries

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