page_title: Polygonaceae
section_title: Description
hierarchical_section_title: Polygonaceae / Description
caption_attribution_description: English: This image shows the stem of a Redshank plant (Persicaria maculosa) and in particular it shows the ocreae, which is the sheath around the stems just above the joint. The ocreae is in fact evolved from fused stipules. Camera: Nikon D50 Location: In a pile of soil/compost behind the Botanical Garden in Gothenburg, Sweden Svenska: Bilden visar en stipelslida på en sv:Åkerpilört.
context_page_description: The Polygonaceae are a family of flowering plants known informally as the knotweed family or smartweed—buckwheat family in the United States. The name is based on the genus Polygonum, and was first used by Antoine Laurent de Jussieu in 1789 in his book, Genera Plantarum. The name may refer to the many swollen nodes the stems of some species have, being derived from Greek, poly meaning 'many' and gony meaning 'knee' or 'joint'. Alternatively, it may have a different derivation, meaning 'many seeds'.
  The Polygonaceae comprise about 1200 species distributed into about 48 genera. The largest genera are Eriogonum, Rumex, Coccoloba, Persicaria and Calligonum. The family is present worldwide, but is most diverse in the North Temperate Zone.
  Several species are cultivated as ornamentals. A few species of Triplaris provide lumber. The fruit of the sea grape is eaten, and in Florida, jelly is made from it and sold commercially. The seeds of two species of Fagopyrum, known as buckwheat, provide grain. The petioles of rhubarb are a food item. The leaves of the common sorrel are eaten in salads or as a leaf vegetable.
context_section_description: Most Polygonaceae are perennial herbaceous plants with swollen nodes, but trees, shrubs and vines are also present. The leaves of Polygonaceae are simple, and arranged alternately on the stems. Each leaf has a peculiar pair of fused, sheathing stipules known as an ochrea. Those species that do not have the nodal ochrea can be identified by their possession of involucrate flower heads. The flowers are normally bisexual, small, and actinomorphic, with a perianth of three to six sepals.  After flowering, the sepals often become thickened and enlarged around the developing fruit. Flowers lack a corolla and in some, the sepals are petal-like and colorful. The androecium is composed of three to eight stamens that are normally free or united at the base. The ovary consists of three united carpels that form a single locule, which produces only one ovule. The ovary is superior with basal or free-central placentation. The gynoecium terminates in 1 to 3 styles, each of which ends in a single stigma.
caption: Ochrea of Persicaria maculosa
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