Publication

Parasitism has evolved in different forms and multiple times independently among plants. The most diverse type of parasitism is based on an organ called haustorium, which promotes the connection between the parasite and the host. These haustorium parasites are often further classified into hemi- and holoparasites based on their ability to photosynthesize and produce some of their own carbohydrates. Among hemiparasites, there are mistletoes and root parasites, such as the sandal wood tree (Santalum album L.). On the other hand, there are a variety of holoparasites, which lack chlorophyll and obtain all their carbohydrates from the host plant, such dodders (Cuscuta spp. L.). Despite also lacking chlorophyll, mycoheterotrophic plants represent a different form of parasitism. These plants lack a haustorium and do not obtain resources directly from a host plant, but rather establish highly specific connections with fungal networks from which they obtain their carbohydrates. These parasitic plants are attracting increased scientific attention, with some groups used as model systems to learn more about ecological interactions and evolutionary dynamics.

 

Taken together, these fascinating parasitic plants can influence forest biodiversity, structure, and composition. In some cases, they are considered important pests, while in other cases they are considered high-priority conservation taxa. 

 

This special issue presents eight papers, one of which focuses on a holoparasite and another focuses on two common mycoheterotrophs in northern temperate forests. Holmes (Mycoheterotrophic plants as indicators of post-agricultural forest regeneration: abundance of Hypopitys monotropa Crantz and Monotropa uniflora L. in post-agricultural forests changes through time) used a chronosequence approach to investigate the occurrence of these two mycoheterotrophs in forests of southern Ohio, USA that have regrown after deforestation and agricultural uses. This approach provides insight into how forest biodiversity recovers after major disturbance. In a novel discovery, Teixeira-Costa (Cannibal plants: intraspecific autoparasitism among host-specific holoparasites) describes autoparasitism where the holoparasite is host to another holoparasite individual of the same species. Although autoparasitism is well documented in hemiparasites, it has never been described before in holoparasites.