 In tropical areas, it can grow more or less continuously and may reach high into the canopy of shrubs and trees; in cold temperate regions, it is an annual plant and is restricted to relatively low vegetation that can be reached by new seedlings each spring.Dodder is parasitic on a very wide variety of plants, including a number of agricultural and horticultural crop species, such as alfalfa, lespedeza, flax, clover, potatoes, chrysanthemum, dahlia, helenium, trumpet vine, ivy and petunias.It is an ectoparasite and is categorized as holoparasitic plant, or a plant that is non-photosynthetic and is completely dependent on a host.