Hexalectris

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Crested coralroot
Hexalectris spicata Arkansas.jpg
Hexalectris spicata
Scientific classification Red Pencil Icon.png
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Epidendroideae
Tribe: Epidendreae
Subtribe: Bletiinae
Genus: Hexalectris
Raf.
Type species
Hexalectris spicata
(Walter) Barnhart

Hexalectris (crested coralroot) [1] is a genus of the family Orchidaceae, comprising 10 known species of fully myco-heterotrophic orchids. [2] These species are found in North America, with the center of diversity in northern Mexico. [3] None of the species are particularly common. [4] Hexalectris spicata has a wide distribution and is likely the most abundant member of the genus, but is nevertheless infrequent throughout its range. [4] Other species are rare, and some, such as H. colemanii, are threatened or endangered. [5] All species that have been studied form associations with ectomycorrhizal fungi that are likely linked to surrounding trees. [6] Many Hexalectris species are found in association with oak trees (Quercus), which are ectomycorrhizal. [7]

Contents

Species

Species accepted as of June 2014: [3]

ImageScientific nameDistribution
Hexalectris arizonica (S.Watson) A.H.Kenn. & L.E.Watson (2010)Arizona, New Mexico, Texas, Coahuila
Hexalectris brevicaulis L.O.Williams (1940)central and southern Mexico
Hexalectris colemanii (Catling) A.H.Kenn. & L.E.Watson (2010)southern Arizona
Hexalectris fallax M.I.Rodr. & R.González (2005)Jalisco
Hexalectris grandiflora (A.Rich. & Galeotti) L.O.Williams (1944)widespread from Texas and Chihuahua south to Oaxaca
Hexalectris nitida L.O.Williams (1944)from Texas and New Mexico to southern Mexico
Hexalectris parviflora L.O.Williams (1940)from Sonora to Guatemala
Hexalectris revoluta Correll (1941)western Texas, southeastern New Mexico, northeastern Mexico
Hexalectris spicata (16977585464).jpg Hexalectris spicata (Walter) Barnhart (1904)United States from Arizona east to Florida and Maryland
Hexalectris warnockii - cropped.jpg Hexalectris warnockii Ames & Correll (1943Arizona, New Mexico, Texas, northern Mexico

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<span class="mw-page-title-main">Burmanniaceae</span> Family of flowering plants

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<span class="mw-page-title-main">Russulaceae</span> Family of fungi in the order Russulales

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<i>Pterospora</i> Genus of plants

Pterospora, commonly known as pinedrops, woodland pinedrops, Albany beechdrops, or giant bird's nest is a North American genus in the subfamily Monotropoideae of the heath family, and includes only the species Pterospora andromedea. It grows as a mycoheterotroph in coniferous or mixed forests. It is widespread across much of Canada as well as the western and northeastern United States to and northern Mexico. Along with Monotropa it is one of the more frequently encountered genera of the Monotropoideae.

<i>Galeola</i> Genus of orchids

Galeola is a genus of orchids belonging to the subfamily Vanilloideae.

<i>Corallorhiza</i> Genus of orchids

Corallorhiza, the coralroot, is a genus of flowering plants in the orchid family. Except for the circumboreal C. trifida, the genus is restricted to North America.

<i>Corallorhiza trifida</i> Species of plant

Corallorhiza trifida, commonly known as early coralroot, northern coralroot, or yellow coralroot, is a coralroot orchid native to North America and Eurasia, with a circumboreal distribution. The species has been reported from the United States, Canada, Russia, China, Japan, Korea, India, Nepal, Kashmir, Pakistan, and almost every country in Europe.

<span class="mw-page-title-main">Myco-heterotrophy</span> Symbiotism between certain parasitic plants and fungi

Myco-heterotrophy is a symbiotic relationship between certain kinds of plants and fungi, in which the plant gets all or part of its food from parasitism upon fungi rather than from photosynthesis. A myco-heterotroph is the parasitic plant partner in this relationship. Myco-heterotrophy is considered a kind of cheating relationship and myco-heterotrophs are sometimes informally referred to as "mycorrhizal cheaters". This relationship is sometimes referred to as mycotrophy, though this term is also used for plants that engage in mutualistic mycorrhizal relationships.

<i>Rhizopogon</i> Genus of fungi

Rhizopogon is a genus of ectomycorrhizal basidiomycetes in the family Rhizopogonaceae. Species form hypogeous sporocarps commonly referred to as "false truffles". The general morphological characters of Rhizopogon sporocarps are a simplex or duplex peridium surrounding a loculate gleba that lacks a columnella. Basidiospores are produced upon basidia that are borne within the fungal hymenium that coats the interior surface of gleba locules. The peridium is often adorned with thick mycelial cords, also known as rhizomorphs, that attach the sporocarp to the surrounding substrate. The scientific name Rhizopogon is Greek for 'root' (Rhiz-) 'beard' (-pogon) and this name was given in reference to the rhizomorphs found on sporocarps of many species.

<i>Epipogium aphyllum</i> Species of hardy myco-heterotrophic orchid lacking chlorophyll

Epipogium aphyllum, the ghost orchid is a hardy myco-heterotrophic orchid lacking chlorophyll.

<i>Corallorhiza mertensiana</i> Species of orchid

Corallorhiza mertensiana, or Pacific coralroot, is a coralroot orchid native to the shady conifer forests of northwestern North America. It also goes by the common names Western coralroot and Mertens' coralroot. Corallorhiza mertensiana was previously considered a subspecies of Corallorhiza maculata but was given species rank in 1997 by Freudenstein.

<i>Limodorum</i> Genus of orchids

Limodorum is a genus of myco-heterotrophic orchids. All species are temperate terrestrial plants and occur across much of Europe, North-West Africa, the Mediterranean Islands, and as far east as Iran. Plants have evolved away from photosynthesis and as a result their leaves are reduced to scales. There is still chlorophyll present but the plants are believed to be solely dependent on their fungal partner for nutrients. They spend most of their life underground as a short stem with fleshy roots, the unbranched inflorescence can appear in April to June if conditions are favourable.

Hexalectris arizonica, the spiked crested coralroot or Arizona crested coralroot, is a terrestrial, myco-heterotrophic orchid lacking chlorophyll and subsisting entirely on nutrients obtained from mycorrhizal fungi in the soil. It is native to Arizona, New Mexico, Texas and Coahuila. It is closely related to H. spicata and sometimes regarded as a variety of that species.

<i>Hexalectris spicata</i> Species of orchid

Hexalectris spicata, the spiked crested coralroot, is a terrestrial, myco-heterotrophic orchid lacking chlorophyll and subsisting entirely on nutrients obtained from mycorrhizal fungi in the soil. It is native to Arizona, New Mexico, Texas and Coahuila. It is closely related to H. arizonica and the two are sometimes considered varieties of the same species. Hexalectris spicata is endemic to the southern half of the United States from Arizona east to Florida and north to Maryland and the Ohio Valley.

Hexalectris grandiflora, the largeflower crested coralroot or giant coral-root, is a species of orchid native to Mexico from Chihuahua south to Oaxaca, as well as to western and north-central Texas. It is a myco-heterotrophic species, lacking chlorophyll and subsisting entirely on nutrients obtained by fungi in the soil.

Hexalectris colemanii, or Coleman's crested coralroot, is a terrestrial, myco-heterotrophic orchid lacking chlorophyll and subsisting entirely on nutrients obtained from mycorrhizal fungi in the soil. It is a very rare species endemic to southern Arizona, known from only three counties. It is closely related to H. revoluta and the two are sometimes considered varieties of the same species.

Hexalectris revoluta, the Chisos Mountain crested coralroot, is a terrestrial, myco-heterotrophic orchid lacking chlorophyll and subsisting entirely on nutrients obtained from mycorrhizal fungi in the soil. It is closely related to H. colemanii; the two are regarded by some authors as varieties of the same species. Hexalectris revoluta is native to western Texas, southeastern New Mexico and Chihuahua.

<i>Hexalectris warnockii</i> Species of orchid

Hexalectris warnockii, the Texas crested coralroot, Texas purple-spike, is a myco-heterotrophic orchid found in the states of Texas and Arizona in the southwestern United States, and in the states of Coahuila and Baja California Sur in northern Mexico. Being myco-heterotrophic, H. warnockii derives all of its nutrients from mycorrhizal fungi.

Orchid mycorrhizae are endomycorrhizal fungi which develop symbiotic relationships with the roots and seeds of plants of the family Orchidaceae. Nearly all orchids are myco-heterotrophic at some point in their life cycle. Orchid mycorrhizae are critically important during orchid germination, as an orchid seed has virtually no energy reserve and obtains its carbon from the fungal symbiont.

<i>Rhizopogon salebrosus</i> Species of fungus

Rhizopogon salebrosus is a mushroom species within the Rhizopogon sub-genus Amylopogon. R.salebrosus is a monotropoid mycorrhiza that is of vital importance to the ecology of conifer forests, especially in the Pacific Northwest region of North America. Although it is native to North America, R. salebrosus has been found in Europe and its range is generally limited to mountainous regions with sufficient precipitation. The mycoheterotrophic plant, Pterospora andromedea is often found in an obligate association with R. salebrosus in western parts of the U.S. Eastern populations of P. andromedea are typically symbiotic with another Rhizopogon sub species, R. kretzerae.

References

  1. USDA, NRCS (n.d.). "Hexalectris". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 14 May 2015.
  2. "Flora of North America".
  3. 1 2 Kew World Checklist of Selected Plant Families
  4. 1 2 Luer, Carlyle A (1975). The native orchids of the United States and Canada, excluding Florida. New York: New York Botanical Garden. OCLC   1348145.
  5. Kennedy, Aaron H.; Watson, Linda E. (2010). "Species Delimitations and Phylogenetic Relationships within the Fully Myco-heterotrophic Hexalectris (Orchidaceae)". Systematic Botany. 35 (1): 64–76. doi:10.1600/036364410790862489. S2CID   85734959.
  6. Kennedy, Aaron H.; Taylor, D. Lee; Watson, Linda E. (2011-03-01). "Mycorrhizal specificity in the fully mycoheterotrophic Hexalectris Raf. (Orchidaceae: Epidendroideae)". Molecular Ecology. 20 (6): 1303–1316. doi:10.1111/j.1365-294x.2011.05000.x. ISSN   1365-294X. PMID   21255173. S2CID   17740766.
  7. Coleman, Ronald A. (2005). "Populations Studies in Dichromanthus and Hexalectris in Southeastern Arizona". Selbyana. 26 (1/2): 246–250. JSTOR   41760196.