Obligate parasites are organism which obtain their food from host throughout their life, eg, Rafflesia, Orobanche (root parasite). Facultative parasites are organism which are normally parasitic but can obtain their food from dead organic matter under certain conditions. Obligate root parasite Rafflesia, Orobanche. Partial stem parasite Viscum, Loranthus. Partial root parasite Santalum. Obligate stem parasite Cuscuta.