Glossopetalon spinescens explained

Glossopetalon spinescens, syn. Forsellesia spinescens, is a species of flowering shrub in the family Crossosomataceae known by the common names greasebush, spiny greasebush, Nevada greasewood and spring greasebush.

It is native to Mexico and the western United States, where it grows in mountainous habitats, often on limestone substrates.

Common names

Glossopetalon spinescens known by the common names greasebush,[1] spiny greasebush,[2] [3] [4] [5] Nevada greasewood (in California),[6] [7] spring greasebush[7] and spiny greasewood, depending on location/source.

The name 'greasewood' is also a common name for Larrea tridentata in Texas.[8]

The different varieties of this species have also been given separate common names when they were still regarded as distinct species, i.e. plains greasebush for G. planitierum, etc.[9]

Description

This shrub forms a dense, erect clump of many thin, branching, thorny stems approaching 3m (10feet) in maximum height.[3] [10] The green oval leaves are less than two centimeters long.[10]

Small white-petalled flowers appear in the leaf axils.[10] The fruit is a single or double follicle a few millimeters wide, and 3 to 5mm long.[10] [3] A follicle is a fruit which splits lengthwise when it is ripe to release its seeds. It is longitudinally striated or ribbed, and coloured green when young, turning light brown.[5]

Taxonomy

Glossopetalon spinescens was described by the American botanist Asa Gray in 1853, based on a specimen collected by Charles Wright in 1852 in a mountain ravine near a location called 'Frontera', in either New Mexico or Texas.[1] It is the type species for the genus Glossopetalon.[11]

G. spinescens is conceived at this time as a widespread and morphologically variable species, unlike the other three (as of 2015) recognised species of Glossopetalon, which are all restricted endemics with more narrowly variable morphologies. Six more-or-less geographical, intergrading varieties were recognized as of 2015.[10] [3]

Mason mentions in 2015 that the morphological characteristics distinguishing a particular variety are not reliable, and some named varieties seem to occur sympatrically with other varieties, whereas some varieties appear to be found in disjunct populations, thus that it was important a study should be done investigating the genetics of the different populations of the varieties.[3] A 2021 study did just that. It found that G. spinescens was largely split into two main geographic lineages: a northwest one and a southeast one. The taxa G. clokeyi and G. texense were found to belong to either lineage respectively, and could therefore no longer parsimoniously be seen as distinct species. Consequently, both taxa were reduced to new varieties. A ninth additional variety was described from northern Arizona on the basis of its divergent DNA: goodwinii.[12] It remains unclear which varieties exist in the southern half of Mexico.[3]

Distribution and habitat

Glossopetalon spinescens occurs across a wide range, from southeastern Washington state in the north,[1] south to isolated disjunct populations in the south of Mexico (Guanajuato, Oaxaca, Tlaxcala and Veracruz).[3]

Besides the Mexican states mentioned above, G. spinescens also occurs in the states of Chihuahua, Coahuila, Nuevo León, Sonora and Tamaulipas.[5]

In the US it occurs, from north to south and west to east, in the states of Washington, Idaho, Montana, Oregon, Wyoming, California, Nevada, Utah, Colorado, Arizona, New Mexico, Oklahoma and Texas. It is not widespread in these states, but is rather localised to a number of counties.[1] [2] [4] In general, this is a rare plant, found most often in scattered concentrations.[1] In Montana and Wyoming it is especially rare, only occurring in a single county (Beaverhead and Sweetwater, respectively).[1] It grows in chaparral and brush country, rocky slopes, canyons and cliffs.[15]

Ecology

It occurs in calcareous soils on limestone.[4] [5] It occurs at altitudes of approximately 850 to 2200m in Arizona.[5] It grows on hillsides, rocky slopes and crevices and ledges of cliffs in canyons and outcrops in desert scrub, grasslands, chaparral and juniper woodland habitats.[4] [5]

It flowers from March to September throughout its range,[4] March or April to May in Arizona.[5]

External links

Notes and References

  1. Web site: Glossopetalon spinescens . Schneider . Al . Southwest Colorado Wildflowers . Rocky Mountain Biological Laboratory of Gothic, Colorado . 16 February 2022.
  2. Web site: Glossopetalon spinescens A. Gray . . PLANTS . United States Department of Agriculture, Natural Resources Conservation Service . 16 February 2022.
  3. Book: Mason . Charles T. Jr. . Yatskievych . George . 15 January 2015 . Glossopetalon spinescens . Flora of North America north of Mexico . 9: Magnoliophyta: Picramniaceae . http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=220005655 . Flora of North America Editorial Committee . 978-0-19-534029-7.
  4. Web site: Glossopetalon spinescens . . 30 October 2020 . Lady Bird Johnson Wildflower Center . The University of Texas at Austin . 16 February 2022.
  5. Web site: Glossopetalon spinescens A. Gray . . 2017 . SEINet Portal Network . . 17 February 2022.
  6. Web site: CROSSOSOMATACEAE . Shevock . James R. . 1993 . Treatment from the Jepson Manual . Regents of the University of California . 16 February 2022.
  7. Web site: Glossopetalon spinescens A. Gray . . GRIN-Global - U.S. National Plant Germplasm System . United States Department of Agriculture, Agricultural Research Service . 16 February 2022.
  8. Book: Loughmiller . Campbell . Loughmiller . Lynn . 1984 . Texas Wildflowers . Austin, TX . University of Texas Press . 241 . 0-292-78060-5.
  9. Web site: Glossopetalon spinescens var. planitierum . . 27 October 2010 . Lady Bird Johnson Wildflower Center . The University of Texas at Austin . 16 February 2022.
  10. Mason, C.T. 1992. Crossasomataceae, Crossosoma Family. Journal of the Arizona-Nevada Academy of Science 26:7-9.
  11. Ensign . Margaret . Margaret Ensign . March 1942 . A Revision of the Celastraceous Genus Forsellesia (Glossopetalon) . The American Midland Naturalist . 27 . 2 . 501–511 . 10.2307/2421016 . 2421016.
  12. Allen . Maya L. . Ayers . Tina . 25 October 2021 . A Revised Classification of Glossopetalon (Crossosomataceae) Based on Restriction Site-Associated DNA Sequencing . Systematic Botany . 46 . 3 . 562–572 . 10.1600/036364421X16312067913417. 240155253 .
  13. Web site: NatureServe. Glossopetalon clokeyi. NatureServe Explorer. 2018-09-30.
  14. Holmgren . Noel H. . September 1988 . Glossopetalon (Crossosomataceae) and a New Variety of G. spinescens from the Great Basin, U.S.A. . Brittonia . 40 . 3 . 269–274 . 2807471 . 10.2307/2807471. 1988Britt..40..269H . 42189852 .
  15. Web site: Lady Bird Johnson Wildflower Center - The University of Texas at Austin . 2024-06-19 . www.wildflower.org.