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Proatriplex pleiantha
Proatriplex pleiantha

Proatriplex pleianthaSynonym: Atriplex pleiantha. (Mancos Shadscale).
Amaranthaceae (Amaranth Family)
(formerly Chenopodiaceae, Goosefoot Family)

Semi-desert. Shrublands, openings. Spring.
Above and left: McElmo Canyon, Canyons of the Ancients National Monument, April 2, 2005 and April 18, 2017.

Dozens of two inch tall seedlings of this annual are crowded into a square foot of hot, dense soils of the Morrison Formation in McElmo Canyon. Plants will grow to just six inches tall.

This species was discovered for science by Colorado plant authority William Weber in 1949 near the Manco River's junction with the San Juan River, and it was at that time named Atriplex pleiantha. Click to read Weber's 1950 description of this new species.

In 1990 Stutz and Chu placed the species in the genus Proatriplex and Weber now agrees with the Proatriplex designation. Weber indicates that although the genus Proatriplex (comprised of just this one species) resembles Atriplex, it is distinct in that it has "more than one flower enclosed in the bract pair, perianth segments (unknown in Atriplex), completely separate bracts, the embryo inverted in position, a different leaf anatomy, and a lower chromosome number".

"Pleiantha" means "more flower". "Atriplex" is an ancient Latin name for a now unknown plant; the name was applied to the genus in modern times by Linnaeus in 1753. "Pro" was added to Atriplex to indicate that this genus originated before Atriplex.

Proatriplex pleiantha

Proatriplex pleiantha

Proatriplex pleianthaSynonym: Atriplex pleiantha. (Mancos Shadscale).
Amaranthaceae (Amaranth Family)
(formerly Chenopodiaceae, Goosefoot Family)

Semi-desert. Shrublands, openings. Spring.
McElmo Canyon, Canyons of the Ancients National Monument, April 2, 2005.

Clusters of flowers are just emerging. The inflorescence is of axillary clusters of unisexual flowers with the terminal flowers staminate, lower flowers pistillate, and middle flowers mixed. Staminate flowers have their filaments united at the base forming a disc.

                                       Proatriplex pleiantha

Proatriplex pleinantha

Proatriplex pleinantha

Proatriplex pleianthaSynonym: Atriplex pleiantha. (Mancos Shadscale).
Amaranthaceae (Amaranth Family)
(formerly Chenopodiaceae, Goosefoot Family)

Semi-desert. Shrublands, openings. Spring.
McElmo Canyon, Canyons of the Ancients National Monument, April 2, 2005.

I enhanced the color of the leaf to bring out the myriad sparkling spheres that cover the surface. These spheres, each about 1/4 mm, are full of a sweet-scented liquid and they impart a majestic jeweled appearance to the plant.

The reds of anthocyanins often give the plant an additional glow.

Although all but one flora indicate that the leaves of P. pleiantha are "alternate to subopposite", I find that plants in the McElmo area have opposite leaves. Flora Neomexicana III indicates that the species has alternate leaves. Perhaps this is based on those plants observed in San Juan County, New Mexico, 40-90 miles south of the McElmo area where the photographs on this page were taken. Proatriplex pleiantha is found in New Mexico, Colorado, and Utah only within a small area near the Four Corners. See the map below.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Proatriplex pleiantha

Range map for Proatriplex pleiantha