A leafless forest jewel
Hidden on the floor of mature conifer and aspen forests, the Striped Coralroot (Corallorhiza striata) sends up a striking, leafless stalk. This plant completely lacks chlorophyll, the green pigment responsible for photosynthesis. Instead of green, its stem can be red, pink, or yellowish-green, reaching heights of 15 to 50 centimeters. The leaves are reduced to mere colorless scales that sheath the stem. The plant's name, Corallorhiza, is Greek for "coral-root," referring to its thick, branched underground rhizomes that resemble sea coral. The species name, striata, is Latin for "striped," describing the flower's stripes.
Each stem is topped by a raceme—a flower cluster—of 15 to 35 individual blooms. The flowers have yellowish or pink sepals and petals marked with prominent deep red or purple stripes. Each flower's lower petal, or labellum, is broad and often a solid reddish-purple. This orchid has a wide distribution, growing across much of southern Canada, the western United States, and Mexico.
A three-part symbiosis
Corallorhiza striata is a mycoheterotroph, a plant that gets its nutrients not from making its own food, and by stealing them from fungi. This makes it a parasite. The relationship is different from direct parasitism on a tree. The orchid taps into an existing mycorrhizal network, where fungi and the roots of photosynthetic trees have a mutually beneficial relationship. The fungus provides the tree with water and minerals, and the tree provides the fungus with sugars produced during photosynthesis. The Striped Coralroot hacks this system, stealing the sugars from the fungus that the fungus received from the tree. Researchers have found that some coralroots, including Corallorhiza, often associate with fungi from the family Russulaceae.
This parasitic lifestyle dictates its entire life cycle. The plant's seeds are dust-like and contain no food reserves. For a seed to germinate, it must land in soil containing a compatible fungus to provide the initial energy for growth. The plant can live underground for several years, emerging only to flower when conditions are favorable. Even its pollination is specialized; one documented pollinator is a parasitic wasp, Pimpla pedalis.