Mycoheterotrophic Plants of New England

Mycorrhizal Associations (Mycorrhizae)

The vast majority of vascular plants have symbiotic associations with certain fungi (i.e., mycorrhizal fungi), which colonize the plant's roots. Often the association is mutually beneficial — the fungi greatly increase the supply of nutrients and water to the plant by increasing the surface area available for absorption; the fungi benefit by obtaining organic carbon (i.e., sugars) from the plant. However, the two partners don't always benefit equally, and in some cases the symbiosis is advantageous to only one of the partners.

What's a Mycoheterotrophic Plant?

Mycoheterotrophic plants obtain nutrients and organic carbon from mycorrhizal fungi and provide little or nothing in return (i.e., they are parasitic on mycorrhizal fungi). Because the mycorrhizal fungi obtain organic carbon from another plant, mycoheterotrophic plants are indirectly parasitic on other plants. A plant that obtains all of its nutrients and organic carbon from mycorrhizal fungi is said to be "holo-mycoheterotrophic," while a plant that is only partially dependent on mycorrhizal fungi for nutrients and organic carbon may be described as "hemi-mycoheterotrophic." Holo-mycohetertrophic plants generally lack chlorophyll and thus tend to be colors other than green. In contrast, hemi-mycoheterotrophic plants contain chlorophyll and are typically green-colored.

In New England, mycoheterotrophic species are found in at least three families of flowering plants, one family of ferns, and in the lycopod family, as described below.

Flowering Plants - Eudicots

Ericaceae (Heath Family)

The heath family includes holo- and hemi-mycoheterotrophic species. Three genera found in New England are holo-mycoheterotrophic (Monotropa, Hypopitys, and Pterospora) and four genera are hemi-mycoheterotrophic (Chimaphila, Moneses, Orthilia, and Pyrola). The mycoheterotrophic species occurring in New England are listed below.

• Chimaphila maculata (striped wintergreen)
• Chimaphila umbellata (pipsissewa)
• Hypopitys lanuginosa (hairy pinesap)
• Hypopitys monotropa (yellow pinesap)
• Moneses uniflora (one-flowered pyrola)
• Monotropa uniflora (Indian pipe)
• Orthilia secunda (one-sided pyrola)
• Pterospora andromedea (pine drops)
• Pyrola americana (round-leaved shinleaf)
• Pyrola asarifolia (pink pyrola)
• Pyrola chlorantha (green shinleaf)
• Pyrola elliptica (elliptic-leaved shinleaf)

Gentianaceae (Gentian Family)

Bartonia species, members of the gentian family, are believed to be holo- or hemi-mycoheterotrophic. Three species of Bartonia are known to occur in New England:

• Bartonia iodandra (Purple screwstem)
• Bartonia paniculata (twining screwstem)
• Bartonia virginica (Virginia screwstem)

Flowering Plants - Monocots

Orchidaceae (Orchid Family)

All orchids are believed to be dependent on mycorrhizal fungi for their source of organic carbon during at least a portion of their life cycle (i.e., as seedlings and during dormancy). Over 20 genera of orchids have been documented in New England. Most orchid species found in New England contain green pigment and photosynthesize at least to some degree as mature plants. A known exception is Corallorhiza maculata (spotted coralroot), which lacks chlorophyll and obtains all of its organic carbon from mycorrhizal fungi.

Fern Clade

Ophioglossaceae (Adder's Tongue Family)

Members of this family of ferns are holo-mycoheterotrophic and subterranean during their gametophyte stage. The sporophytes are photosynthetic. Two genera occur in New England: Botrychium and Ophioglossum. The species are listed below.

• Botrychium angustisegmentum (narrow triangle moonwort)
• Botrychium ascendens (upswept moonwort)
• Botrychium campestre (prairie moonwort)
• Botrychium dissectum (cut-leaved grapefern)
• Botrychium onondagense (Onondaga moonwort)
• Botrychium neolunaria (new world moonwort)
• Botrychium matricariifolium (daisy-leaved moonwort)
• Botrychium minganense (Mingan moonwort)
• Botrychium multifidum (leathery grapefern)
• Botrychium oneidense (blunt-lobed grapefern)
• Botrychium pallidum (pale moonwort)
• Botrychium rugulosum (St. Lawrence grapefern)
• Botrychium simplex (least moonwort)
• Botrychium spathulatum (spoon-leaved moonwort)
• Botrychium tenebrosum (swamp moonwort)
• Botrychium virginianum (rattlesnake fern)
• Ophioglossum pusillum (northern adder's tongue fern)

Lycopod Clade

Lycopodiaceae (Clubmoss and Firmoss Family)

Members of this family are mycoheterotrophic during their gametophyte stage and photoautotrophic during their sporophyte stage. In New England, five genera have gametophytes that are holo-mycoheterotrophic and live below ground: Dendrolycopodium, Diphasiastrum, Huperzia, Lycopodium, and Spinulum. Two genera, Locopodiella and Pseudolycopodiella, have gametophytes that live above ground and are hemi-mycoheterotrophic. The following species of lycopods are found in New England:

• Dendrolycopodium dendroideum (prickly tree clubmoss)
• Dendrolycopodium hickeyi (Hickey's tree clubmoss)
• Dendrolycopodium obscurum (flat-branched tree clubmoss)
• Diphasiastrum complanatum (northern ground cedar)
• Diphasiastrum digitatum (southern ground cedar)
• Diphasiastrum sitchense (Sitka ground cedar)
• Diphasiastrum tristachyum (blue ground cedar)
• Huperzia appressa (mountain firmoss)
• Huperzia lucidula (shining firmoss)
• Huperzia selago (northern firmoss)
• Lycopodiella alopecuroides (foxtail bog clubmoss)
• Lycopodiella appressa (appressed bog clubmoss)
• Lycopodiella inundata (northern bog clubmoss)
• Lycopodium clavatum (common clubmoss)
• Lycopodium lagopus (one-cone clubmoss)
• Pseudolycopodiella caroliniana (slender false bog clubmoss)
• Spinulum annotinum (bristly clubmoss)
• Spinulum canadense (northern interrupted clubmoss)