Layia discoidea

Taxobox
name = "Layia discoidea"


image_width = 240px
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
subclassis = Asteridae
unranked_ordo = Euasterids II
ordo = Asterales
familia = Asteraceae
genus = "Layia"
species = "L. discoidea"
binomial = "Layia discoidea"
binomial_authority = Keck

"Layia discoidea" is a rare species of flowering plant in the daisy family known by the common name rayless tidytips, or rayless layia. It is endemic to California, where it is known only from the Diablo Range in southern San Benito County and far western Fresno County. It is a member of the serpentine soils flora. This is an annual herb growing a small glandular stem to a maximum height of about 20 centimeters. The thin leaves are generally lance-shaped, but the larger leaves on the lower part of the stem are usually lobed. Unlike other tidytips species, which are known for their sharply white-tipped yellow ray florets, the rayless tidytips has no ray flowers or real phyllaries. The flower head is a cluster of many golden disc florets with a base of bractlike scales. The fruit is an achene with a short scaly brown pappus.

Genetic analysis performed on this species suggest that it evolved directly from "Layia glandulosa" in what may be an example of both allopatric speciation and peripatric speciation. [Baldwin, B. G. (2005). Origin of the serpentine-endemic herb "Layia discoidea" from the widespread "L. glandulosa" (Compositae). "Evolution" 59:11 2473-79.] "Layia discoidea" looks quite different from the white-rayed "Layia glandulosa", and it lives in a specialized habitat, but the two species are genetically very similar and produce robust, fertile hybrids when crossed. [Gottlieb, L. D., S. I. Warwick and V. S. Ford. (1985). Morphological and electrophoretic divergence between "Layia discoidea" and "L. glandulosa". "Systematic Botany" 10:4 484-95.]

References

External links

* [http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?609,1504,1507 Jepson Manual Treatment]
* [http://plants.usda.gov/java/profile?symbol=LADI4 USDA Plants Profile]
* [http://calphotos.berkeley.edu/cgi/img_query?query_src=photos_index&where-taxon=Layia+discoidea Photo gallery]