Lasthenia

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Goldfields
Lasthenia glabrata 1.JPG
Yellow-ray Goldfields
Lasthenia glabrata
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Asterales
Family: Asteraceae
Subfamily: Asteroideae
Tribe: Heliantheae
Genus: Lasthenia
Cass.
Type species
Lasthenia californica
DC. ex Lindl.
Species

18

Lasthenia, commonly known as goldfields, is a genus of the botanical family Asteraceae. The genus is named after Lasthenia, a cross-dressing female pupil of the ancient Greek philosopher Plato.

Description[1][edit]

The goldfield genus comprises annual, rarely perennial herbs that are as either glabrous or hairy. Stems are typically branched and erect, attaining a height of less than 60 centimeters. Their opposite leaves, of length of up to 20 centimeters are entire to pinnate.

Inflorescences are characterized by solitary heads (sometimes in cymes), with phyllaries free or partly fused. The receptacle may present as naked and narrowly conic to hemispheric. The normally yellow ray flowers may number four to 16, and the ligules are typically yellow as well. The disk flowers are numerous and generally yellow corollae are typically five-lobed; anther tips manifest as acuminate to triangular, while style tips may be triangular or round, but typically hair-tufted.

Fruits are less than five millimeters across, cylindric to obovoid in shape, and black or gray in color. The pappus may present awns or scales, or infrequently neither. The genus is mostly cross-pollinated, with some insects serving as pollinators.

Ecology and horticulture[edit]

Goldfield species occur over a range of habitat, such as meadows, shrubland and open forest, but tend towards semiarid conditions. They are commonly found at ephemeral pools and are important plants in coastal regions. They are visited by Sciaridae fungus gnats for nectar, and it is possible that these animals are key pollinators at least for Contra Costa Goldfields (L. conjugens).

In horticulture, most make hardy ornamental plants, suitable for flower-beds or borders. Autumn is the best time for sowing the seed, but it may also be sown early in the spring.[2]

Species[edit]

L. californica

There are a total of eighteen species, seventeen are endemic to North America and one species is only found in Chile. Of the seventeen species found in North America, most are endemic to California.

Lasthenia californica subsp. californica – California Goldfields (found in northern California and Oregon)
Lasthenia californica subsp. bakeri – Baker's Goldfields (endemic to California)
Lasthenia californica subsp. macrantha – Perennial Goldfields (endemic to California)
Lasthenia glabrata subsp. glabrata – Yellow-ray Goldfields (endemic to California)
Lasthenia glabrata subsp. coulteri – Coulter's Goldfields (endemic to California)

Footnotes[edit]

  1. ^ Chan & Ornduff (2006)
  2. ^ Pink (2004)
  3. ^ Ornduff (1966)

References[edit]

  • Chan, Raymund & Robert Ornduff (2006): Lasthenia. In Flora of North America North of Mexico, Vol. 21: Asteraceae. Flora of North America Editorial Committee (eds.). Oxford University Press, New York, New York.
  • Ornduff, Robert (1966): A biosystematic survey of the goldfield genus Lasthenia (Compositae: Helenieae). University of California Publications in Botany 40: 1-92.
  • Pink, Alfred (2004): Gardening for the Million.