This is an evergreen climber which clings by means of tiny stem roots to masonry, trees, cliffs and rocks and which carpets the ground in dense shade and under hedges.
Ivy can be a very destructive plant when growing on graves and walls. Stems of ivy will grow through cracks and crevices and as the stems expand they force apart considerable size stones. Ivy is however a valuable source of late nectar for insects and of berries, particularly for wood pigeons.
The early leaves are three or five-lobed, shiny dark green with pale veins and the more mature leaves are often heart-shaped. The leaves remain on the plant throughout the year and from September to November they are joined by little yellow-green flowers (8–10 mm across). These have five pointed lobes and five prominent stamens, are borne in umbels. In the following spring, the berries develop, ripening purple-black. These are poisonous if eaten in quantity and it might be useful to know that the sap contains an irritant to the skin which can induce dermatitis. This is a native plant and it belongs to the Araliaceae family. Also found less commonly in Ireland is Hedera helix, with some small differences but best differentiated from Hedera hibernica by having whitish rather than light brown hairs on growing tips. Some of the little hairs on the leaves project from the leaf-surface in Hibernica helix, whereas they lie flat to it in Hedera hibernica.
This information is courtesy of http://www.wildflowersofireland.net/