Rhubarb in the context of Polygonaceae

Buckwheat (Fagopyrum esculentum) or common buckwheat is a flowering plant in the knotweed family Polygonaceae cultivated for its grain-like seeds and as a cover crop. Buckwheat cultivation originated around the 6th millennium BC in the region of what is now Yunnan Province in southwestern China. The name "buckwheat" is used for several other species, such as Fagopyrum tataricum, a domesticated food plant raised in Asia.

Despite its name, buckwheat is not closely related to wheat, nor is it a cereal or a member of the grass family. It is related to sorrel, knotweed, and rhubarb. Buckwheat is considered a pseudocereal because the high starch content of the seeds enables buckwheat to be cooked and consumed like a cereal.

This list contains the names of fruits that are considered edible either raw or cooked in various cuisines. The word fruit is used in several different ways. The definition of fruit for this list is a culinary fruit, defined as "Any edible and palatable part of a plant that resembles fruit, even if it does not develop from a floral ovary; also used in a technically imprecise sense for some sweet or semi-sweet vegetables, some of which may resemble a true fruit or are used in cookery as if they were a fruit, for example rhubarb."

Many edible plant parts that are considered fruits in the botanical sense are culinarily classified as vegetables (for example, tomatoes, zucchini), and thus do not appear on this list. Similarly, some botanical fruits are classified as nuts (e.g. Brazil nut) and do not appear here either. This list is otherwise organized botanically.

Reynoutria japonica, synonyms Fallopia japonica and Polygonum cuspidatum, is a species of herbaceous perennial plant in the knotweed and buckwheat family Polygonaceae. Common names include Japanese knotweed and Asian knotweed. It is native to East Asia in Japan, China and Korea. In North America and Europe, the species has successfully established itself in numerous habitats; it is classified as a pest and invasive species in several countries. The plant is popular with beekeepers and its young stems are edible, making it an increasingly popular foraged vegetable with a flavour described as lemony rhubarb.

Edible plant stems are a part of plants eaten by humans. Most plants are made up of stems, roots, leaves, flowers, and produce fruits containing seeds. Humans most commonly eat the seeds (e.g. maize, wheat), fruit (e.g. tomato, avocado, banana), flowers (e.g. broccoli), leaves (e.g. lettuce, spinach, and cabbage), roots (e.g. carrots, beets), and stems (e.g. asparagus of many plants. There are also a few edible petioles (also known as leaf stems) such as celery or rhubarb.

Plant stems have a variety of functions. Stems support the entire plant and have buds, leaves, flowers, and fruits. Stems are also a vital connection between leaves and roots. They conduct water and mineral nutrients through xylem tissue from roots upward, and organic compounds and some mineral nutrients through phloem tissue in any direction within the plant. Apical meristems, located at the shoot tip and axillary buds on the stem, allow plants to increase in length, surface, and mass. In some plants, such as cactus, stems are specialized for photosynthesis and water storage.

Caryophyllales (/ˌkæri.oʊfɪˈleɪliːz/ KARR-ee-oh-fih-LAY-leez) is a diverse and heterogeneous order of flowering plants with well-known members including cacti, carnations, beets, quinoa, spinach, amaranths, pigfaces and ice plants, oraches and saltbushes, goosefoots, sundews, Venus flytrap, tropical pitcher plants, Malabar spinach, bougainvilleas, four o'clock flowers, buckwheat, knotweeds, rhubarb, sorrels, purslanes, jojoba, and tamarisks. Many members are succulent, having fleshy stems or leaves.

The betalain pigments are unique in plants of this order and occur in all its core families with the exception of Caryophyllaceae and Molluginaceae. Noncore families, such as Nepenthaceae, instead produce anthocyanins. In its modern definition, the order encompasses a whole new group of families (formerly included in the order Polygonales) that never synthesize betalains, among which several families are carnivorous (like Nepenthaceae and Droseraceae).

Rheum is a genus of about 60 herbaceous perennial plants in the family Polygonaceae. Species are native to eastern Europe, southern and eastern temperate Asia, with a few reaching into northern tropical Asia. Rheum species are cultivated in Europe, Asia, and North America. The genus includes the vegetable rhubarb. The species have large somewhat triangular shaped leaves with long, fleshy petioles. The flowers are small, greenish-white to rose-red, and grouped in large compound leafy inflorescences. Many rhubarb cultivars have been domesticated as medicinal plants and for human consumption. While the leaves are slightly toxic, the stalks are used in pies and other foods for their tart flavour.

Anthrone is a tricyclic aromatic ketone. It is used for a common cellulose assay and in the colorimetric determination of carbohydrates.

Derivatives of anthrone are used in pharmacy as laxative. They stimulate the motion of the colon and reduce water reabsorption. Some anthrone derivatives can be extracted from a variety of plants, including Rhamnus frangula, Aloe ferox, Rheum officinale, and Cassia senna. Glycosides of anthrone are also found in high amounts in rhubarb leaves, and alongside concentrated amounts of oxalic acid are the reason for the leaves being inedible.

Rheum rhabarbarum is a species of flowering plant in the family Polygonaceae, native to a region stretching from southern Siberia to north and central China. It has been harvested from the wild for centuries for its root, which was harvested for use as a popular medicine in Europe and Asia. It was later cultivated for its root in England and Russia. It is considered to be one of the species involved in the development of culinary rhubarb, for which the scientific name R. rhabarbarum is sometimes (erroneously) used.

Rheum rhaponticum, the false rhubarb, rhapontic rhubarb or rhapontic, is a plant species in the genus Rheum found in the wild. It is the only Rheum species found only in Europe, and is now restricted to the Rila mountain range in south-western Bulgaria. It was introduced to other countries in Europe. It is considered to be one of the parents of the modern culinary rhubarb.