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Intraspecific autoparasitism, the phenomenon in which a parasite serves as the host for another individual of the same species, is a well-described interaction among hemiparasitic flowering plants. Here, I describe a rare case of autoparasitism in Epifagus virginiana (L.) W.P.C. Barton (Orobanchaceae), a holoparasitic plant normally found exclusively on the roots of Fagus grandifolia Ehrh. (Fagaceae). Confirmation of the autoparasitic relationship was obtained through microtomography and anatomical analyses. Results show the presence of vessel connections between the two E. virginiana plants and the unobstructed passage of solutes from one plant to another, thus suggesting the autoparasitic connection to be fully functional. While several segments of nearby host roots were entangled with the adventitious roots of the parasite, no parasite–host vascular connection was detected. Additionally, an analysis of digitized herbarium specimens showed that albeit rare, the observed autoparasitic relationship in E. virginiana is not a one-of case. A total of 3097 digitized herbarium specimens were also analyzed, among which 1.69% were observed to potentially include an autoparasitic connection. Altogether, these results provide new clues for the investigation of host-specificity and haustorium development processes in parasitic flowering plants. [ABSTRACT FROM AUTHOR]

Abstract: The study of plant phenology deals with seasonal events and how these are influenced by environmental factors, including symbiotic interactions. Considering host-mistletoe associations, our goal was to analyze the [...]

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Background and Aims Balanophoraceae is one of the most bizarre and biologically interesting plant clades. It groups species with peculiar features that offers an opportunity for investigating several aspects of parasite plant development and morphogenesis. We analysed the development and the mature vegetative body of Lathrophytum peckoltii Eichler, focusing on the formation of the host–parasite interface. Additionally, we analysed how this parasitic interaction causes modifications to the anatomy of Paullinia uloptera Radlk and Serjania clematidifolia Cambess host roots. Methods Vegetative bodies of the parasite at different developmental stages were collected while infesting the roots of Sapindaceae vines. Non-parasitized host roots were also collected for comparison. Light, epifluorescence, confocal and scanning electron microscopy were used for the analysis. Key Results The initial cells of the vegetative axis divide repeatedly, originating a parenchymatous matrix, which occupies the space from the cortex to the vascular cylinder of the host's root. In the peripheral layers of the matrix, located near the xylem of the host's roots, a few cells initiate the process of wall lignification, originating the parasitic bundle. The vascular cambium of the host's root changes the division plane and becomes composed of fusiform initials, forming the vascular bundle. The vegetative axis presents a dermal tissue similar to a phellem, a parenchymatous matrix and a vascular system with different origins. Conclusion The parasite reproduces by endophytic development, in a manner similar to that observed for endoparasites. The strategy of late cell differentiation could aid the parasite in avoiding early detection and triggering of defence responses by the host. This development causes changes to the host root cambial activity, leading to the establishment of direct, vessel to vessel connection between host and parasite. We associate these changes with the cambium modularity and an influx of parasite-derived hormones into the host cambium. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses articles in the issue on topics including Parasitic Flowering Plants in Forests, Focus on a Holoparasite, Two Common Mycoheterotrophs in Northern Temperate Forests, and other related topics.

• Soil temperature and moisture level exhibited the strongest influence in a range of functional traits measured in the underground tuber of Epifagus virginiana. • E. virginiana reacts to differences in litter quantity by producing more grapplers and investing in cell lignification, especially under more favorable microenvironmental conditions. • Soil pH showed significant effects on E. virginiana both within and between populations. Epifagus virginiana (Orobanchaceae), known as beechdrops, is a holoparasitic plant that acquires all its resources from a narrow range of host plants, restricted to North American Fagus species. To do so, beechdrops develop a vascular connection with the host via a terminal haustoria that develops as a tuber attached to the host root. We hypothesized that microenvironmental conditions can influence functional traits of the E. virginiana tuber despite this parasite's complete reliance on the host plant for its nutrition. Therefore, the aims of this study were i) to analyze the structure of the tubers of E. virginiana ; ii) to assess the variation in tuber functional traits between two E. virginiana populations; and iii) to analyze how microenvironmental factors influence functional traits in the tuber. We detected that functional trait of beechdrops tuber along Mexican beech microenvironmental covaried with traits important for below-ground processes. Boosted regression trees provided a powerful analysis tool, giving substantially superior predictive performance to generalized additive models, despite the fitting of interaction terms in the latter. [ABSTRACT FROM AUTHOR]