Eriogonum

Read about Eriogonum in the Standard Cyclopedia of Horticulture
Eriogonum (Greek, woolly joints). Polygonaceae. About 140 species, W. N. American (with extension into Mex.), herbs tufted sub-shrubs or slender annuals, mostly densely woolly: lvs. crowded at the base of the St., alternate or whorled, entire: fls. small, perfect, in an involucrate head, fascicle or umbel, mostly recurved or reflexed with age, mostly white, rose or yellow; perianth 6-parted; stamens 9; styles 3: fr. an achene, mostly 3-angled. Now and then some of the species are listed by dealers in native plants, but they can hardly be regarded as cult. subjects. E. compositum, Douglas, perhaps the best known, has very many minute neutral- colored fls., dull white to rosy, borne in compound umbels 5-6 in. deep and broad. B.R. 1774. The following have been advertised, but are practically unknown in our gardens: E. campanulatum, E. compositum, E. flavum, E. heracleoides, E. incanum, E. microthecum var. effusum, E. niveum, E. nudum, E. ovalifolium, E. racemosum, E. sphaerocephalum, E. thymoides, E. umbellatum. E. giganteum makes a mound or mat many feet across. G.C. III. 28:337. Descriptions of eriogonums may be readily found in the floras of the western part of the U. S. The above text is from the Standard Cyclopedia of Horticulture. It may be out of date, but still contains valuable and interesting information which can be incorporated into the remainder of the article. Click on "Collapse" in the header to hide this text.

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Wild buckwheats

Sulphur Flower
Eriogonum umbellatum

Plant Info

Scientific classification

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Caryophyllales
Family:	Polygonaceae
Genus:	Eriogonum Michx. (1803)

Species

Over 250, see text

Eriogonum is the scientific name for a genus of flowering plants, in the family Polygonaceae. The genus is found in North America and is known as Wild Buckwheat. This is a highly species-rich genus, and indications are that active speciation is continuing. It includes some common wildflowers such as the California Buckwheat (Eriogonum fasciculatum).

It came into the news in 2005 when the Mount Diablo Buckwheat (Eriogonum truncatum, believed to be extinct) was rediscovered.

Importance for Lepidoptera

Eriogonum species are used as food plants by the larvae of some Lepidoptera (butterflies and moths). Several of these are monophagous, meaning that their caterpillars only feed on this genus, sometimes just on a single taxon of Eriogonum. Wild buckwheat flowers are also an important source of food for these and other Lepidoptera. In some cases, the relationship is so close that Eriogonum and dependent Lepidoptera are in danger of coextinction.

Monophagous Lepidoptera on wild buckwheat include:

Apodemia mormo (Mormon metalmark) - feeds exclusively on Eriogonum
- Apodemia mormo langei (Lange's metalmark) - only known from Eriogonum nudum ssp. auriculatum
Chionodes dammersi - feeds exclusively on Eriogonum
Chionodes luteogeminatus - only known from Eriogonum niveum
Euphilotes enoptes smithi (Smith's blue butterfly) - only known from Eriogonum latifolium and Eriogonum parvifolium