Anatomy, Embryology and Life Cycle of Lophophytum, a Root-Holoparasitic Plant

Abstract

The most extreme manifestation of parasitism occurs in holoparasites, plants that are totally achlorophyllous. Among them, the genus Lophophytum (Balanophoraceae) is characterized by an aberrant vegetative body called a tuber, devoid of stems and leaves. The genus is exclusively South American, comprising five taxa, which parasitize the roots of trees or shrubs. This review focuses on the Argentine species of the genus: L. leandri and L. mirabile subsp. bolivianum. Topics covered include: morphology and anatomy of the vegetative body and host–parasite connection; structure, anatomy and development of the staminate and pistillate flowers; sporogenesis and gametogenesis, embryo sac inversion; endospermogenesis, embryogenesis and fruit development. The evolutionary trend in the gynoecium and embryo sac of the Balanophoraceae is also discussed to reflect the variability. Finally, observations were made on the synchronization of the life cycles of the parasites and hosts to infer possible ways by which parasitism has evolved, until now unknown.