Orobanche ramosa is a parasite that attaches itself underground to the roots of other plants. It then drains nutrients from these hosts, not possessing leaves and chlorophyll itself. Orobanche, Striga and other genera that do not have any chlorophyll are called holoparasites. Some Orobanche species are annual, others biennial or perennial (Wikipedia).
The plant is originally from North Africa, Europe and Asia, but has spontaneously spread even more widely or somehow introduced as in South Africa. In several parts of the world certain species of this genus, commonly known as broomrape or hemp broomrape, have become agricultural pests, infesting crops like tomato, potato, tobacco and ornamental plants. It then understandably appears on several official lists of noxious or prohibited weeds in various parts of the world (http://plants.usda.gov).
The name originates from the Greek words orobus meaning vetch (certain kinds of herbal plants) and anchein meaning to strangle. The plant may eventually strangle its host by depriving it of its nutrients (http://fernkloof.com).