Lasthenia

Taxobox
name = Goldfields


image_width = 200px
image_caption = Yellow-ray Goldfields "Lasthenia glabrata"
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
subclassis = Asteridae
unranked_ordo = Euasterids II
ordo = Asterales
familia = Asteraceae
genus = "Lasthenia"
genus_authority = Cass.
subdivision_ranks = Species
subdivision = About 18, see text.

"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 [Ornduff (1966)]

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 21, 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

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. [Pink (2004)]

pecies

There are a total of eighteen species, seventeen are endemic to North America and one is only found in Chile. Of the seventeen species found in North America, most are endemic to California.
*"Lasthenia burkei" – Burke's Goldfields (endangered)
*"Lasthenia californica" – California Goldfields (found in northern California, Oregon, and Baja California)
*"Lasthenia chrysantha" – Alkali-sink Goldfields (endemic to California)
*"Lasthenia conjugens" – Contra Costa Goldfields (endangered)
*"Lasthenia coronaria" – Crowned Goldfields, Royal Goldfields (found in California and northern Mexico)
*"Lasthenia debilis" – Greene's Golfdields (endemic to California)
*"Lasthenia ferrisiae" – Ferris's Goldfields (endemic to California)
*"Lasthenia fremontii" – Fremont's Goldfields (endemic to California)
*"Lasthenia glaberrima" – Smooth Goldfields (found in California, Oregon, Washington, and British Columbia)
*"Lasthenia glabrata" – Yellow-ray Goldfields (endemic to California)
*"Lasthenia gracilis" – Common Goldfields (found in California, Arizona, the Channel Islands of California, and northern Mexico)
*"Lasthenia kunthii" – Chilean Goldfields (found in vernal pools in Chile)
*"Lasthenia leptalea" – Salinas Valley Goldfields (endemic to California)
*"Lasthenia maritima" – Maritime Goldfields, Seaside Goldfields (found along the coast and offshore islands and islets from California to British Columbia)
*"Lasthenia microglossa" – Small-ray Goldfields (endemic to California)
*"Lasthenia minor" – Coastal Goldfields (endemic to coastal and inland California)
*"Lasthenia ornduffii" – Ornduff's Goldfields(endemic to Oregon, endangered)
*"Lasthenia platycarpha" – Alkali Goldfields (near-endemic to California)

Footnotes

References

* (1966): A biosystematic survey of the goldfield genus "Lasthenia" (Compositae: Helenieae). "University of California Publications in Botany" 40: 1-92.
* (2004): [http://www.gutenberg.org/etext/11892 Gardening for the Million.]