Subalpine, alpine. Scree. Summer.
Stony Pass, July 17, 2010.

This tiny alpine plant is, according to Weber, "locally common on screes at high elevations", but overall it is listed as rare in the very few Colorado and New Mexico counties in which it is found.

It has long been believed that the only other occurrences of this plant are in the Altai Mountains of Siberia, where it was first discovered and where it is also rare. As of 2020 the Flora of North America states, "Stellaria irrigua has a remarkable and perhaps uniquely disjunct distribution". However, in 2019 Sharples and Tripp published research (click to read) which indicates,

"Stellaria irrigua is one of several plants that has been treated as an exceptionally dramatic example of a disjunction between floristically similar, high alpine biotas of the southern Rocky Mountains and south‐central Siberia.... Sampled Asian populations formed two clades, and North American individuals all formed a clade embedded within this broader Asian lineage. Stellaria irrigua is, however, rendered non‐monophyletic by a lineage that is embedded within the North American populations and is ecologically and morphologically distinctive from S. irrigua. The identity of this newly recognized lineage, which was in prior works attributed to S. irrigua, has been confused since plants of the former were first collected in the San Juan Mountains of Colorado in the late 1800s under Arenaria and Alsine. We provide a new name for this taxon, Stellaria sanjuanensis, a charismatic starwort of dry alpine scree slopes of the southern Rocky Mountains."

Stellaria sanjunaensis is unusual also, as the photographs show, in its floral structure.  The white petals are cut deeply and they and the stamens are laid back against the colorful bracts.  Leaves and bracts are green and maroon. 

The plant is minute and difficult to find on alpine scree slopes.

Bunge named this plant in 1835 from Siberian specimens. Sharples and Tripp's research shows that the name Stellaria irrigua is still a valid name, but that species is what has formerly been called Stellaria umbellata.

Subalpine, alpine. Scree. Summer.
Clear Lake near Silverton, July 20, 2010.

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

Range map for Stellaria sanjuanensis