Buckwheat

Species of bistorta are perennial herbaceous plants. Their roots are fibrous forming rhizomes. They have erect unbranched stems. Their leaves are usually longer than wide mostly basal but with some arranged alternately on the stems. The inflorescences are spikelike. The individual flowers have five white to purple-pink (rarely red) tepals. The flowers are bisexual although the 5–8 stamens are sometimes poorly developed. There are three styles. The fruits are in the form of achenes that are brown or dark brown unwinged and three-angled. As of winter 2019 about 42 species are accepted. Bistorta species are native throughout much of the Northern Hemisphere as far south as Mexico in North America and Thailand in Asia.

Woodland threadstem is genus containing only a single species. Woodland threadstem is a very small annual spreading or climbing plant with very thin, hairy stems. The tiny leaves are lobed or heart-shaped and may be green or pink. The plant may sprawl across the ground in a thin layer or may form small patches here and there. The plant bears tiny bright pink flowers. The plant is native to the United States and Northwestern Mexico.

Species of koenigia are annual or perennial herbaceous plants, growing from taproots. The flowers are arranged in terminal or axillary inflorescences. The flowers have pale tepals: white, greenish to yellowish white or pink. The seeds are borne in achenes that are usually brown or black in colour and not winged. Koenigia species are found in meadows, along stream banks, or on rocky slopes in arctic, temperate and alpine regions of the Northern Hemisphere.

Wild Buckwheat are noted for their woolly leaves and petite, delicately cupped blooms arranged in a cluster. This diverse range of perennials, annuals, and evergreen shrubs are native to North America. Wild Buckwheat are wildflowers that are often cultivated for rock and alpine gardens and are drought tolerant.

Coccoloba is a genus containing mostly tropical and subtropical trees, shrubs, and woody vines. The leaves tend to be large, and the flowers bloom in spikes. Few of these plants are of commercial or ornamental importance – one species, however, the Seagrape (C. uvifera), is cultivated across the Caribbean. Genetic analysis suggests that the genus originated in Central America, although many of its species have spread both north and south.

Species of pteroxygonum are twining vines growing from a large woody globe-shaped tuber. Their leaves are broad and palmate with a dark red mark around each primary leaf vein. The inflorescence is in the form of an axillary raceme. The flowers are bisexual with five spirally arranged tepals eight stamens joined at the base and three styles also joined up to about the middle. Their fruits are in the form of winged three-angled achenes. As of spring 2019 two species are recognized. Their native range is from Tibet to southeast China.

The reynoutria form a very small genus of large, flowering plants in the buckwheat (sometimes called knotweed) family. A few species within this genus are utilized by beekeepers for their pollen production. The genus on the whole, however, is more famous for hosting several invasives, most notable among these being Japanese Knotweed (R. japonica). Japanese Knotweed, now found in temperate regions around the world, is considered one of the most aggressive and harmful invasive plant species on the planet.

The buckwheat vine genus comprises herbaceous vines native to North America. Some species are commercially important because of their popularity among beekeepers, while others can grow among other commercial crops such as soybeans, damaging plants and affecting yields. Most species have broad leaves and unpretentious flowers.

Lovechains are flowering vines native to the Americas. They have attractive bell-shaped flowers that come in pink and purple shades, with some being white or yellowish. Some species, grown as ornamentals for the showy blooms and rapid growth, are among the most invasive weeds in tropical and island ecosystems globally due to their efficient reproduction.

The knotweeds (Polygonum) are a sizable and diverse group of mostly temperate flowering plants. Several species within this genus have historically been eaten by humans, although few have been widely cultivated as food sources. One exception to this is Madimak (P. cognatum), which is quite popular as a green in Turkish cuisine, and is today heavily cultivated in the central part of that country. Being hardy, colonizing species that spread quickly, several knotweeds are also considered pesky invasives beyond their native ranges.

The rhubarbs (Rheum) are a group of large-leafed flowering plants in the buckwheat (sometimes called knotweed) family. This genus is most famous for its edible species. Although their leaves are toxic, their thick red stems are edible and sport a tart flavor – they're often used in desserts and pastries such as pies. Additionally, a handful of rhubarbs species are grown ornamentally, being prized for their large, showy leaves.

Spineflowers are small, squat, herbaceous plants with spiny-looking inflorescences of flowers. The flowers may be in shades of red or yellow to white. The bracts are pointed and sometimes tipped with a hooked awn, and the inflorescence often dries into a rounded, spiny husk. Spineflowers are found in western North America and South America.

Maidenhair may be identified by their thin stem, unremarkable flowers, and small alternate leaves. Maidenhair are deciduous or evergreen semi-climbers or shrubs that do not like chilly winds and can sometimes become weedy in gardens.

Mountain sorrels is a genus of plants in the family Polygonaceae with three accepted species as of spring 2019. It has a circumboreal distribution. Species of mountain sorrels are perennial herbaceous plants or weakly shrubby. They spring have rhizomes. Their stems are erect variably branched. Undivided leaves are present both at the base of the plant and on the stems. They are arranged alternately and have stalks (petioles). The inflorescences are terminal paniclelike or racemelike borne on stems (pedunculate). Individual flowers are either bisexual or unisexual with four greenish to reddish brown tepals. The fruits are in the form of achenes with broadly winged margins.

Calligonum is a genus of plants in the family Polygonaceae with about 80 species across the Mediterranean Sea region, Asia and North America. Plants of the genus calligonum are shrubs, diffusely but irregularly branched, with flexuous woody branches. Leaves are simple, opposite, nearly sessile, linear or scale-like, sometimes absent or very small, linear or filiform, distinct or united with short membranous ochreae. Flowers are bisexual, solitary or in loose axillary inflorescences.

Fagopyrum (Fagopyrum) are a small genus whose species include several important food plants. Although native to India and China, various species have been widely introduced worldwide. Generally, plants in the fagopyrum genus have five-petaled flowers and despite the common name "Buckwheat," are not related to wheat. Some species are also used for filling in pillows and upholstered products.

Docks (Rumex) are a large and widespread group of flowering plants in the buckwheat (sometimes called knotweed) family. Many species within this genus have been used by humans for centuries. Sorrels, a subgroup of docks, have tart-tasting leaves that are cultivated for use as salad greens. The roots of several docks also contain high levels of tannins and have been used for tanning leather.

The fallopia form a small genus in the buckwheat family containing temperate and sub-tropical shrubs. A few species within the genus, most notably Japanese Knotweed (F. japonica) are famous for being pesky invasives. In their native ranges, however, fallopia do tend to provide food to insects and birds.

Species of knorringia are perennial herbaceous plants growing to about 41 cm tall from a slender, often branched rhizome. The leaves are arranged alternately, usually lobed, carried on a short five-sided leaf stalk with two distinct wings. The inflorescence is either a panicle made up of a few racemes or a single raceme. The flowers usually have five greenish-white tepals and eight stamens, included within the flower. The fruits are in the form of achenes. The seeds have a thick outer layer and a very thin inner layer. It is native to Central Asia and Siberia.

When the genus is defined narrowly polygonella species are annual or perennial herbaceous plants rarely shrubby with much branched stems. The leaves are arranged alternately with a length greater than the width. The flowers are usually bisexual rarely unisexual and have five (occasionally four) tepals the outer being slightly different from the inner ones. The fruit is three-sided. As of winter 2019 Plants of the World Online accepted 129 species. The genus primarily grows in northern temperate regions.

As of spring 2019 Plants of the World Online accepted 41 species. Species of atraphaxis are much branched woody plants forming shrubs or shrubby tufts. The leaves are simple and alternate with very short stalks (almost sessile). The inflorescence is made up of several bundles (fascicles) of one to three flowers. The flowers have persistent tepals either arranged in a narrow tube with unequal lobes or bell-shaped with equal segments. The fruits are wingless achenes.

The persicaria (Persicaria) are a large, diverse, and widely distributed group of flowering plants. Hardy and bearing colorful flower inflorescences, several persicaria are grown ornamentally. They tend to flower from midsummer through mid-fall. Gardeners should be careful with which species they choose to cultivate, though, as several persicaria have also become highly invasive in areas where they've been introduced.