Description: Targionia is a genus of thalloid liverworts in the order Marchantiales. The thalloid gametophyte is generally seen as a ribbon of tissue, green if wet, and black if dry. This “ribbon” is robust, leathery, and opaque, with surfacial pores venting air chambers in the thick thallus. Epidermal pores are surrounded by specialized cells like the bulging trigones (triangular-shaped wall thickening in the corner of a cell where it abuts against two other cells). Presence, shape, and size of trigones are characteristic of some liverwort genera. Thallus is either male or female, each having specialized organs. Capsules mature on the underside of the thallus.
Habitat: Liverworts (about 8,500 species) are found throughout the world, from the arctic to the tropics. Known from dry places to aquatic habitats, with most adapted to moist habitats. This Targionia species occurs in deeply shaded habitats, often associated with ferns, specifically along north sides of boulders, or in deeply recessed cliff overhangs. Elevations: above 1,220 m (4,000 ft).
Range: This Targionia species appears to be a Mojave Desert endemic. In Clark County, Nevada, known from the Red Rock Canyon National Conservation Area near White Rock Spring, in the Newberry Mountains near Christmas Tree Pass, and in the Eldorado Mountains near the mouth of Keyhole Canyon.
Comments: This Targionia liverwort, a rare species, is a recent discovery. It will be described shortly by Dr. Alan Whittemore, Missouri Botanical Garden.