There are over 160 Eriogonium species, most of which are found in the Western United States. In June two Erigonium species were prominent in one of our fields near Lookout CA (Modoc County).
Rock buckwheat (Eriogonum sphaerocephalum) is a native perennial growing in dry, rocky places between 2,000 and 7,000 feet. It is found in the Great Basin areas of Washington, Oregon, California, Idaho and Nevada. It has a woody stem and is considered a wildflower or shrub (sub-shrub).
A member of the Buckwheat Family (Polygonaceae), rock buckwheat grows from a caudex (rootstock). The grey, lanceolate leaves occur in whorls at each stem node. The leaf undersides are densely covered with matted hairs while the upper sides are less hairy.
The rock buckwheat inflorescence is a single terminal umbel (flower stalks originating from a common point). There is a bract at the base of the umbel. Each cream to sulfur yellow flower has two rows of tepals, 9 stamens and a one-celled superior ovary. There is a hairy line up the underside of each tepal.
Rock buckwheat fruits are light brown, three-angled achenes sparsely pubescent at the beak.
E sphaerocephalum is also commonly known as round-headed buckwheat. The genus name, as mentioned in previous posts, means “woolly joint” because some members have hairs at the joints. The species designation comes from the Greek words “sphaira/globe” and “kefali/head” and refers to the round inflorescence.
My next post will be the other Eriogonum species on our field.