 Many variants of T. grandiflorum have green markings on the petals , as well as anywhere from 4 to 30 extra petals or bracts along with other highly deformed characteristics . Although many of these forms have been given taxonomic names , it has been shown that mycoplasma @-@ like bacteria are responsible for the altered morphology in these individuals and not genetic variation . T. grandiflorum does , however , occasionally produce double @-@ flowered forms such as T. g. f. polymerum . These are almost invariably sterile , but are much sought after for their appearance by trillium growers . It is the species of trillium that produces double flowers most frequently . On the other hand , and unlike other species such as T. erectum which hybridize fairly easily , T. grandiflorum is not known to form hybrids . 
