This section is from the book "Wayside And Woodland Blossoms", by Edward Step. Also available from Amazon: Wayside And Woodland Blossoms: A Guide To British Wild-Flowers.
How common is Ivy, whether wild or cultivated! Yet how few are acquainted with its flowers!
There is no occasion to say that the Ivy is an evergreen perennial climbing shrub, nor to describe the form of the beautiful leathery leaf. If there is one leaf that may be said to be thoroughly well known to every British man, woman, and child, it must be the Ivy, for it thrives in dark corners of towns as well as on the hedge-banks of the country, and its foliage has been so well used in all classes of ornamental work. And yet there are few leaves that are subject to such great variation of form, though, with all its changes, one dominant character runs through them all, except its upper leaves, which are totally unlike. The Holly has prickly leaves for its lower branches, but those that are above the heads of browsing cattle have "entire" margins. So with the Ivy; its five-lobed leaves are for its trailing and climbing branches, but when it has reached the top of the wall or the tree it puts on simple lance-shaped leaves, and in September or October crowns these shoots with its umbels of yellow-green flowers.
The flower consists of a calyx with five triangular teeth, petals and stamens five each, style one, with five obscure stigmas. The flowers are succeeded by blackish berries, some times yellow. There is a common woodland variety, with smaller, narrower leaves, that never flowers; neither do those forms that persistently trail along the hedge bottom instead of climbing. Ivy has been at various times condemned as causing dampness in the walls it covers; the exact converse is the truth. It is the only British species; the genus contains but two for the whole world.