1. A parasitic plant that lacks a fully developed root system and forms connections with another plant, from which it obtains some or all of its water and minerals. Such plants have chlorophyll and produce their own food by photosynthesis, and in some cases are capable of limited growth in the absence of the host plant. They tap into the sap-conducting tissue of the host by means of specialized structures called haustoria (see haustorium). Some, such as eyebright (Euphrasia spp.), attach themselves to the roots of their host and appear like normal plants growing in the soil, whereas others grow on the aerial parts of their host. The mistletoes are well-known examples that colonize the branches of trees.

2. A facultative parasite (see parasitism).