Slender Buckwheat

Although slender buckwheat (Eriogonum gracile) may grow two feet high and occur in large numbers, it is such an insubstantial plant that it disappears into the background and is rarely noticed. However, when seen against a plain background  in the right light, a magical plant appears, with golden-pink branchlets decorated with glowing      pom poms.

Slender buckwheat is a California native with limited distribution outside the state. It prefers sandy open areas of sage scrub and chaparral. In The Reserve, in late summer, blooming plants can be found in East Basin, east of the Santa Carina trailhead.

Like the other buckwheats slender buckwheat provides larval food for several small butterflies, especially blues and hairstreaks.

Description ^3,4,59

As the name implies, slender buckwheat is a very slim, erect annual plant growing up to two feet (50 cm) high. One or a few wand-like stems arise from the base of the plant, each stem branching several times. Leaves are mostly basal on short stalks; they are narrowly to broadly elliptical or oblong, and more or less tapered to base;  the margins are smooth and wavy; the lower leaf surface may be slightly to densely woolly. The leaves shrivel before full bloom and thus are rarely seen. The best leaf image we have found is by Keir Morse, seen in CalFlora.⁷

The stems are tan to green, often acquiring a reddish tinge with age.

Small discrete clumps of 20-30 flowers occur along the stems. Flowers are similar to flowers of the more common California buckwheat (E. fasciculatum). They are small, about 1/8 inch (3-4 mm) across. The sepals resemble petals (sometimes called tepals), six in number, flaring outward from a short tube. Flowers open sequentially; young flowers face away from the stem, while older flowers droop; Flower color ranges from white to pink to yellow. In the Reserve, young flowers are usually white with a pink mid-stripe, and older flowers appear yellowish. The main bloom time is May – October.¹

Classification  

Slender buckwheat is a dicot angiosperm in the buckwheat family (Polygonaceae).² In this family, leaves are generally simple (not divided into leaflets) and alternate. Typically, flowers are tiny, symmetrical and clustered close together; sepals resemble petals (called tepals), in two whorls of 3-6 tepals. The fruit is usually small, dry and 1-seeded.^11,44

Other familiar species in the buckwheat family include rhubarb and sorrel as well as true buckwheat, which is a Eurasian species.¹¹

With over 125 species, Eriogonum is the largest dicot genus in California.²⁴  Four species have been reported from The Reserve. Others are California buckwheat (E. fasciculatum), long-stem buckwheat (E. elongatum) and bluff buckwheat (E. parvifolium).⁴⁸

There are two varieties of slender buckwheat in California.⁷ Our variety,  gracile is distinguished from the other variety, incultum, by having flower clusters that are thin to densely woolly (tomentose).²

Ecology  

Slender buckwheat shares several adaptations to our dry climate with other Reserve plants. Like laurel sumac (Malosma laurina), the leaves fold upward along the midvein during periods of water stress;⁴ like twiggy wreath plant (Stephanomeria spp.), the leaves appear during the first part of the growing season and drop off before the peak of the dry season;⁵⁹ and like deerweed (Acmispon glaber), the flowering stems contain chlorophyll so photosynthesis continues at a low level, even after loss of the leaves.⁴

Human Uses  

Although many species in this genus have been used for food and, especially, medicinal purposes, we know of no specific use of slender buckwheat.

Interesting Facts  

Like most species in the buckwheat genus, slender buckwheat is an important nectar source in late summer, attracting a wide variety of insects⁵⁹ including bees and butterflies.¹⁰⁹ Calflora⁷ lists six species of little blues and hairstreaks that specifically use slender buckwheat as a host plant.