These are all over the roadsides, right up next to the bluebonnets, anyone know what this is called? Ya'll are gonna hate me soon, because I know nothing about the flowers I photograph for the most part, but I love finding out about them...
Parasitic plants depend wholey or partially on other plants often of a specific genus,these are often totally or partially deviod of chlorophyll and some appear white or yellow. They depend on other plants for their nutrition and water uptake. The plants which need other plants for their total survival are called holo-parasitic plants. Orobanche is a genus which is holo-parasitic, their common name in Britain is broomrape.
Semi-parasitic or Hemi parasitic plants do have some of their own chlorophyll but still depend on other plants for their survival. Castilleja incivisa is an example as are Pedicularis species (louseworts). My favorite one though is Melampyrum pratense common name cow wheat
Other forms of parasitism include being unable to establish without other plants, being able to survive without other plants but still use them for part of their nutrition and joining their stems to another plant to obtain nutrition.
Grasses, however, do not have a parasitic form as I understand it.