Sanrobertia

Sanrobertia gypsophila is a perennial, herbaceous plant that blooms with lilac rays and yellow disk centers during the months of August through October. It grows from a slender and woody rhizome,[2] with blue-green stems[3] that reach heights between about 4 and 20 cm (2 and 8 in). The plant has either tiny glands on tiny stalks called stipitate glands or it may have glands without stalks. These glands are on its upper stems, leaves, and phyllaries. Most of the plant may be slightly strigose with very short (0.1–0.5 millimeters[lower-alpha 1]), appressed, white, and pointed hairs.[2]

The basionym of Sanrobertia gypsophila is Aster gypsophilus B.L.Turner, first published in 1974.[6] In 1994, Guy L. Nesom reclassified it as Symphyotrichum gypsophilum (B.L.Turner) G.L.Nesom,[1] even though the chromosome count varied from those species; he wrote that it appeared closely related to the virguloid species in the Symphyotrichum genus.[5] In 2012, the results of further molecular analyses of Symphyotrichum and related species were published by David R. Morgan and Blake Holland which clearly placed it as separate from the Symphyotrichum genus.[7] Thus, in 2018, Nesom published it in a monotypic genus within the subtribe Symphyotrichinae of the tribe Astereae.[2] The cladogram shows that the genera Canadanthus, Ampelaster, and Sanrobertia are the earliest diverging members of Symphyotrichinae, developing their morphologies prior to the related species in Symphyotrichum, Almutaster, and Psilactis.[7]

Large colony of S. gypsophila in its natural habitat in Nuevo León, Mexico

Sanrobertia gypsophila is a rare endemic species known only from gypsum flats and llanos near Entronque San Roberto (San Roberto Junction)[2] in southwestern Nuevo León, Mexico, at about 1,800–2,200 meters (5,900–7,200 feet).[8]