Fruit ID #4

Wayne's WordIndexNoteworthy PlantsTriviaLemnaceaeBiology 101BotanySearch

Fruit Identification Photos #4

Achenes Of The Buckwheat Family

Buckwheat Family (Polygonaceae)

Wild Buckwheat,  Knotweed,  Buckwheat,  Gilmania

The buckwheat family (Polygonaceae) contains about 49 genera and 1,000 species. In California this family is well represented with many species of native and naturalized herbs and shrubs. According to the Jepson Manual of California Plants (1993), the genus Eriogonum (wild buckwheat) is the largest genus in California with 113 species, many of which have several named varieties. The leaves of most genera have a peculiar type of stipule called an ocrea, consisting of a pair of stipules united into a membranous sheath that wraps around the stem above the node (point of leaf attachment). The elongation and growth of lateral buds in the leaf axils often causes the ocrea to split or tear.

1. Wild Buckwheats (Eriogonum species)

Left: California wild buckwheat (Eriogonum fasciculatum var. fasciculatum), a common, low-growing shrub in the coastal sage scrub and chaparral of San Diego County. Dense, headlike (capitate) clusters of small white flowers are produced at the tips of leafless stalks (peduncles) in an open cymose or umbel-like inflorescence. The slender (linear), leathery leaves occur in clusters or fascicles at alternate nodes along the stem. Right: Eriogonum reniforme, a minute wild buckwheat native to sandy riverbeds of Anza-Borrego Desert State Park in San Diego County. Like the California buckwheat, the tiny flowers are produced in a cyme-like inflorescence. The leaves are covered with a dense layer of white, wooly hairs (tomentose) which provide insulation and light reflection in the blistering desert sun. A U.S. Penny (one cent) is used for the size relationship.

Desert Trumpet: Another Interesting Buckwheat

The perianth (petal-like and sepal-like floral parts) of most members of the buckwheat family consists of two whorls of three tepals each. The outer whorl occupies the position of sepals and the inner whorl occupies the position of petals Since these segments are not clearly differentiated by size, shape or color, they are referred to as tepals, rather than petals or sepals. The single ovary in each flower develops into a small, hard, one-seeded fruit called an achene. The seed is free within the pericarp (fruit wall) except where it is attached to the placenta. This is quite different from the grain (caryopsis) of the grass family (Poaceae) in which the seed is completely fused with the ovary wall. The achenes of some members of the buckwheat family are eaten and ground into flour like cereal grains. This is particularly true of buckwheat (Fagopyrum esculentum), which is used for hot and cold cereals, pancakes, desserts and many other tasty foods.

See The Familiar Achenes Of The Giant Sunflower

2. Knotweed (Polygonum arenastrum)

Left: Knotweed (Polygonum arenastrum), a European weed that is naturalized throughout southern California where it often forms dense, prostrate mats. This is a prolific seed producer, each plant producing hundreds of shiny black, seed-bearing achenes in the leaf axils. Right: Close-up view of a single flower showing a shiny black achene (A) surrounded by pink-tinged tepals(B). The membranous, fused stipules or ocrea (C) is clearly visible at the base of the leaf. According to Cornucopia by S. Facciola (1990), the achenes of this and a related species (P. aviculare) are ground into flour for pancakes and cookies. The leaves are used as a potherb and as a tea substitute.

3. Buckwheat (Fagopyrum esculentum)

Buckwheat (Fagopyrum esculentum), an important crop plant native to central Asia. The three-sided achenes resemble miniature nuts from the beech tree (Fagus). This resemblance led to the German name "buchweizen" (beech-wheat) which became corrupted to the present name of buckwheat. The nutritious achenes are produced in flower clusters that arise from the axils of triangular-ovate leaves. The hulled achenes or groats are used in several brands of hot and cold breakfast cereals. The seeds are ground into flour which is used for pancakes, noodles and breads. In Russia, a nutritious porridge called "kasha" is made from buckwheat flour.

One-seeded achenes of buckwheat (Fagopyrum esculentum), an important crop plant native to central Asia. The three-sided achenes resemble miniature nuts from the beech tree (Fagus). This resemblance led to the German name "buchweizen" (beech-wheat) which became corrupted to the present name of buckwheat. The hulled achenes or groats are used in several brands of hot and cold breakfast cereals. The seeds are ground into flour which is used for pancakes, noodles and breads. In Russia, a nutritious porridge called "kasha" is made from buckwheat flour.

Two angular nuts of American beech (Fagus grandifolia) within a spiny involucre. The three-sided nuts resemble the miniature one-seeded fruits (achenes) of true buckwheat (Fagopyrum esculentum). This similarity led to the German name "buchweizen" (beech-wheat) which became corrupted to the present name of buckwheat.

Other Edible Members Of The Polygonaceae
See Carribean Shrub Called The Seagrape
See The Colorful Leaf Stalks Of Rhubarb

4. Death Valley Gilmania (Gilmania luteola)

Mud hills along the east side of the floor of Death Valley National Monument, California are eroded into numerous small canyons and gullies. The is the habitat of the rare Gilmania luteola, an endemic herb of the buckwheat family (Polygonaceae). The resistant, dormant achenes of this wildflower survive years of severe drought and temperatures in excess of 120 degrees Fahrenheit. Just when everyone thinks the plant will never appear again, it blooms in profusion on these barren mud hills after sufficient winter rains.

Left: A small gilmania plant (Gilmania luteola) growing from a crack in the mud on the floor of Death Valley National Monument. Occasionally this extremely arid region of Death Valley receives enough moisture to sustain populations of this rare, endemic wildflower. It survives years of drought and temperatures in excess of 120 degrees Fahrenheit through its dormant achenes. Right: The dormant achenes of Death Valley gilmania compared with the eye of an ordinary sewing needle. The shiny, hard-shelled achenes survive years of drought and blistering heat on the mud hills and floor of Death Valley. Each seed-bearing achene is about 1.5 mm in length, slightly larger than a wolffia plant (the world's smallest flowering plant).

See Straight Pin & Sewing Needle Used In Wayne's Word Articles

Go To Identification Of Major Fruit Types
To Economically Important Plant Families
Return To WAYNE'S WORD Home Page
Return To NOTEWORTHY PLANTS Page
Go To Biology GEE WHIZ TRIVIA Page
Go To The LEMNACEAE ON-LINE Page