Anatomy of Pilostyles hamiltonii C. A. Gardner (Rafflesiaceae) in stems of Daviesia

Abstract

In Daviesia stems the vegetative body of Pilostyles hamiltonii occurs as thin strands of undifferentiated cells within the secondary phloem of the host. Parasite cells have prominent nuclei, extended plasmalemma, and lack chloroplasts and amyloplasts. Plasmodesmata are abundant between parasite and host cells. Early vegetative growth of the parasite appears to depend on host phloem tissues for its nutrient requirements. At flower initiation Pilostyles taps the host xylem by producing pegs of tissue across the vascular cambium of the host.