''Epifagus virginiana'', commonly called beech drops (or beech-drops), is an

obligate {{wiktionary, obligate As an adjective, obligate means "by necessity" (antonym ''facultative'') and is used mainly in biology in phrases such as: * Obligate aerobe, an organism that cannot survive without oxygen * Obligate anaerobe, an organism that ...

parasitic plant A parasitic plant is a plant that derives some or all of its nutritional requirements from another living plant. They make up about 1% of angiosperms and are found in almost every biome. All parasitic plants develop a specialized organ called the ...

which grows and subsists on the

root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...

s of

American beech ''Fagus grandifolia'', the American beech or North American beech, is a species of beech tree native to the eastern United States and extreme southeast of Canada. Description ''Fagus grandifolia'' is a large deciduous tree growing to tall, w ...

. It is a member of the family

Orobanchaceae Orobanchaceae, the broomrapes, is a family of mostly parasitic plants of the order Lamiales, with about 90 genera and more than 2000 species. Many of these genera (e.g., ''Pedicularis'', ''Rhinanthus'', ''Striga'') were formerly included in the ...

. The genus ''Epifagus'' is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

—containing only ''E. virginiana''. The name ''Epifagus'' derives from Greek "epi" meaning "on" or "upon", and "Fagus" which is the genus name of beech.

Description

Beechdrops is a parasitic plant native to eastern North America. It entirely lacks

chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to a ...

and produces many brown stems up to 30 cm tall on which it bears small white and purple flowers that appear in July through October. The flowers have tubular, zygomorphic, corollas ~8mm long containing a single style and four stamens. The dried flower stalks will persist throughout the winter. The flowers on the lower parts of the plant are

cleistogamous Cleistogamy is a type of automatic self-pollination of certain plants that can propagate by using non-opening, self-pollinating flowers. Especially well known in peanuts, peas, and pansies, this behavior is most widespread in the grass family. How ...

(self-pollinating) while the tops of the stems have

chasmogamous Chasmogamy, is a plant reproductive mechanism in which pollination occurs in chasmogamous flowers. Chasmogamous flowers are commonly showy with open petals encircling exposed reproductive parts. Chasmogamous stems from Greek for "open marriage", na ...

(cross-pollinating) flowers which may be sterile. Beechdrops contain very small alternate, scale like leaves, which are a

vestigial Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...

structure from an ancestor which was photosynthetic.

Host and symptoms

''Epifagus virginiana,'' also known as beechdrops, is an obligate parasite to '' Fagus grandifolia'', beech trees. It has been found on maple trees but it is believed this is a case of mistaken identity. ''E. virginiana'' grows off of the roots of its host but is not known to cause significant harm to the beech tree. Beechdrops grows on shallow roots at varying distances from the trunk of ''F. grandifolia''. The roots of the host release a chemical that trigger the germination of ''E. virginiana''. It is believed that the older the host tree, the more this chemical is released. The parasite develops a

haustorium In botany and mycology, a haustorium (plural haustoria) is a rootlike structure that grows into or around another structure to absorb water or nutrients. For example, in mistletoe or members of the broomrape family, the structure penetrates t ...

that grows into beech roots to draw nutrients from its host, as beechdrops does not photosynthesize. ''E. virginiana'' does not tolerate disturbances in its connection to ''F. grandifolia''. As ''E. virginiana'' develops a tuber the haustorium diminishes to the point that when ''E. virginiana'' has reached maturity there is no visible haustorium, instead the parasite and host are connected through their roots and the beechdrops’ tuber.

Life cycle

''Epifagus virginiana'' germinates when a chemical signal is released from the beech tree’s roots. During early stages of development, beechdrops lives independently from its host, instead relying on nutrients from the seed. It may take several years for an above ground structure to form. These early stages ''E. virginiana'' are a few millimeters in size and butter yellow. Beechdrops then develops a haustorium that grows into the host’s roots. At maturity the haustorium degrades and a tuber develops. During late summer and early fall ''E. virginiana'' flowers. Beechdrops produces two types of flowers:

and

. Chasmogamous flowers are cross pollinated flowers that grow at the top of the plant and are sometimes sterile. Cleistogamous flowers are self-fertile, these flowers grow at the base of the plant. Seeds from ''E. virginiana'' are small and are dispersed by rainwater. Between dispersal and germination, seeds experience a cellular change, the embryo changes colors and its cells develop granules.

Environment

''Epifagus virginiana’s'' host environment is mainly

temperate forest A temperate forest is a forest found between the tropical and boreal regions, located in the temperate zone. It is the second largest biome on our planet, covering 25% of the world's forest area, only behind the boreal forest, which covers abou ...

s in northeastern North America, including the midwest of the U.S., and Canada. Beechdrops are found in Indiana, Ohio, and Michigan in significant numbers. They have been documented along the East Coast from Maine to South Carolina. In these environments ''E. virginiana'' are pollinated by '' Prenolepis imparis'', the winter ant. This insect pollination is required for pollination in the chasmogamous flowers. ''E. virginiana'' relies upon ant pollination to produce cross pollinated seeds along with self-fertilized seed. It is not believed that ants pollinate the self-fertile cleistogamous flowers. Beechdrops are used to monitor forest health because of their dependence on their host and the sensitivity to its environment. ''E. virginiana’s'' host, beech trees, can advance in a forest faster than ''E. virginiana'' is able to. The presence of ''F. grandifolia'' is used to predict when ''E. virginiana'' will arrive in an area. ''E. virginiana'' is not a tree health concern but the lack of its presence is a sign that forest health is declining.

References

* * {{Taxonbar, from1=Q10273296, from2=Q5382880 Orobanchaceae Parasitic plants Flora of Northern America Plants described in 1818 Monotypic Lamiales genera Orobanchaceae genera