We are used to seeing ivy climbing trees but tend to forget that it is also a great ground cover plant able to colonise large areas of soil, stones and even rock and walls. This is because it uses other plants and structures for support and not for nutrients in the way parasitic plants do. It may be slightly ironic that there is a parasitic plant that takes nutrients from ivy rather than use it merely for support; that plant taking advantage is ivy broomrape (Orobanche hederae).
Although ivy is a very common plant ivy broomrape is not. It only grows on ivy that is spreading rather than climbing and tends also to be coastal. In Dorset we find it along the limestone areas of Purbeck and Portland. often where the soil is poor and not much else other than a strong plant like ivy can survive. It has a creamy flower in June and July and has no leaves; it does not need chlorophyll in leaves as it gets all the nutrients it requires from its host.
I was amazed to see that you can buy packets of seeds of ivy broomrape to plant in your garden and it is thought that this species is increasing in south eastern England partly due to this cultivation leading to it spreading into the wild.