Malaxis unifolia Michx.

Green Adder's Mouth

Facts About

Accepted Synonym: Microstylis unifolia

Malaxis unifolia, commonly known as Green Adder's Mouth, is widely distributed across central and eastern Canada and the U.S., from Texas to Newfoundland. It is a small orchid, no more than 50 cm tall, and produces one or rarely two glossy leaves mid-way up the stem, with a sheathing base that reaches down to the stem's swollen base. It produces up to 160 small green flowers, with a three-lobed labellum and strongly recurved lateral petals. It flowers in spring and early summer in the northern part of its range, while in the south it blooms later into the fall. It can be distinguished from M. monophyllos by its three-lobed labellum, and generally grows in swamps and bogs, habitats too moist for M. bayardii, although it can be found in drier woodlands and forests.

Malaxis unifolia is considered globally secure, although it may be rare in a few central U.S. states.


This orchid is pollinated by species of Aedes (mosquitoes), Bradysia (fungus gnats) and Trioxys (parasitic wasps). A gall midge (Cecidomyiidae) has been observed with pollinium attached to its head and crawling toward the column.

Ecosystem Type

Bogs, forests, swamps, woodlands


Leaf arrangement:
Number of leaves on stem:
  • one
  • two
Form of the labellum:
the labellum is not pouch-like
Labellum outline:
the labellum is lobed
Main color of labellum:
green to brown
Nectar spur:
Inflorescence type:
the inflorescence is a raceme
Labellum characteristics:
the labellum is lobed
Labellum length:
1.1–2.3 mm
Sepal length:
1.1–3 mm
Plant height:
3–35 cm
Show All Characteristics

Native to North America


North American Conservation Status & Distribution

Conservation Status

Select a location to view conservation status:

Conservation and Wetland Status
Global Rank Secure
US Status N/A
Canadian Status Secure

North America Distribution

Adapted from USDA data