User:Eewilson/Sanrobertia

is a genus of flowering plants within the subtribe Symphyotrichinae of the family Asteraceae. It is monotypic, meaning there is only one species within the genus –.

Sanrobertia gypsophila is a rare endemic species known only from gypsum flats and near Entronque San Roberto (San Roberto Junction), Nuevo León, Mexico.

Description
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, with blue-green stems that reach heights between about 4 and 20 cm. 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), appressed, white, and pointed hairs.


 * 0.1–0.5 mm
 * 0.1–0.5 mm
 * 0.1–0.5 mm
 * 0.1–0.5 mm

Leaves
Numerous alternate and simple blue-green leaves grow on the stems and branches, and they are usually somewhat clasping at their bases. Their margins (edges) are smooth, shapes are mostly oblong-lanceolate, and tips are curved slighty outward and covered with a few tiny spines. The single-nerved leaves are without a stalk (known as sessile) and are small, ranging in lengths from 4 to 7 mm and widths from 1 to 2 mm, being generally even in size and distribution along the stems.

Florets
The flower heads of Sanrobertia gypsophila consist of 12–16 lilac ray florets, each about 5–6 mm long and 0.8–1.2 mm wide. These suround a disk of yellow florets.

Chromosomes
S. gypsophila has a monoploid number (also called base number) of nine chromosomes The species is diploid with a total chromosome count of 18.

Taxonomy
The basionym of Sanrobertia gypsophila is Aster gypsophilus.

B.L.Turner, first published it in 1974. and give more info here from his protologue as well as information about holotypes and isotypes

In 1994, Guy L. Nesom reclassified it as Symphyotrichum gypsophilum (B.L.Turner) G.L.Nesom, despite the different chromosome number (base 9) from those species; he wrote that it appeared closely related to the virguloid species in the Symphyotrichum genus. which are base number 5

In 2012, the results of further molecular analyses of Symphyotrichum and related species were published by David R. Morgan and Blake Holland, placing the species as separate from the Symphyotrichum genus. elaboration

In 2018, Nesom published it in the monotypic genus Sanrobertia within the subtribe Symphyotrichinae of the tribe Astereae.

Genera Canadanthus, Ampelaster, and Sanrobertia are the "earliest diverging members of Symphyotrichinae", and developed their morphologies prior to the related species in Symphyotrichum, Almutaster, and Psilactis.

Distribution and habitat
Sanrobertia gypsophila is known only from gypsum flats and near Entronque San Roberto (San Roberto Junction) in southwestern Nuevo León, Mexico, at about 1800–2200 m.