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Stellaria irrigua

Stellaria irrigua

Stellaria umbellata
Stellaria irrigua. Synonym: Stellaria umbellata. (Umbrella Starwort)
Caryophyllaceae (Pink Family)

Upper montane, sub-alpine, alpine.  Forests, moist areas, tundra. Summer.
Above: Sharkstooth Trail, July 30, 2020.
Left: Ophir Pass Road, July 20, 2006.

As common as this plant is, I passed it by for years -- probably thinking it was Bedstraw, Galium boreale -- or not even noticing it.   I should have looked more closely, because this is a strangely interesting plant. The top photograph, which covers just one square foot, gives some indication of how difficult it is to find Stellaria irrigua. There are at least eight Stellaria irrigua in that photo. In the second photograph above in a different location, I zoomed in to make the plants more obvious.  

Stems often lean and twist over each other, sometimes forming a matted thicket two to ten inches tall and six inches wide.  Petal-less dainty earring-like flowers dangle from umbrella spokes; five sepals (2-3 mm long) are green with light margins (see bottom flower in the photograph below).  William Weber notes that the plant is "extremely variable" in appearance and Stanley Welsh notes that it is "one of the most common species of Stellaria in Utah".

All floras until at least 2020 called this species Stellaria umbellata, but genetic research by Sharples and Tripp indicates that the type specimens of what was named S. umbellata and what was named S. irrigua "are for the most part identical" (Sharples and Tripp's words). Porphir Turczaninow (1796-1864) named the Stellaria umbellata species from Asian specimens in 1842 and he noted, according to Sharples and Tripp, that his collection of S. umbellata was morphologically "very similar to Bunge's Stellaria irrigua", also named from Asian specimens. Sharples and Tripp's genetic research shows that the Asian S. irrigua and S. umbellata, are just one species, S. irrigua, the first of the two that was named and described.

The genetic research also showed that the species in the United States which was thought to be the same as the Asian Stellaria irrigua is a distinct North American species. Sharples and Tripp named that species, Stellaria sanjuanensis, as the type specimens are from the San Juan mountains. S. sanjuanensis is found only in a few counties of southern Colorado and one county of northern New Mexico.

 

Stellaria irrigua. Synonym: Stellaria umbellata. (Umbrella Starwort)
Caryophyllaceae (Pink Family)

Upper montane, sub-alpine, alpine.  Forests, moist areas, tundra. Summer.
Ophir Pass Road, July 20, 2006.

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 irrigua