Polygonaceae Plant Family

About the Polygonaceae or Buckwheat Family

Polygonaceae is a family of flowering plants that includes annuals, perennials, shrubs, and vines. This family is widely distributed around the globe, with members found in diverse habitats such as deserts, grasslands, wetlands, and mountains. Many species within Polygonaceae are known for their notable medicinal properties, while others are cultivated for food or ornamental purposes. The family is also ecologically important, providing habitat and food sources for a range of animals.

Taxonomy and Classification

Polygonaceae is a family within the order Caryophyllales, which also includes amaranth, cactus, and carnation families. In Polygonaceae, there are three subfamilies that include around 48 genera. Some of the most well- genera are Rumex, Fagopyrum, and Polygonum.

The family is characterized by their alternate leaves with ochrea or sheathing stipules and swollen nodes. The flowers are usually small and inconspicuous, arranged in spikes, racemes, or panicles. They often have a persistent calyx and no corolla, with six tepals instead. The fruit is usually an achene, sometimes surrounded by the persistent perianth.

Polygonaceae is closely related to the family Plumbaginaceae and shares some common features such as the persistent calyx and lack of corolla.

Morphology and Characteristics

Members of the Polygonaceae family are often robust, herbaceous plants with a wide range of growth habits. They can be annual or perennial, and may be found as herbs, shrubs, or climbers. Most species have distinctive jointed stems that are often hollow and frequently marked by swollen nodes.

The leaves of Polygonaceae plants are usually simple and alternate, although some may be opposite. The leaf base is often sheathing, which forms an ochrea around the stem. The leaves themselves may be smooth or hairy, and can have entire, lobed, or toothed margins.

Flowers in Polygonaceae are typically small, arranged in clusters along stems or at the ends of branches. They lack petals but have six tepals that are fused at the base and form a tube. The tepals are usually colored green, white, pink, or red.

Fruit of Polygonaceae is typically a dry, single- achene that is often enclosed within the remains of the perianth.

Some notable characteristics in this family includes the presence of oxalic acid crystals that give a sour taste and often cause irritation when ingested, and the ability to accumulate high levels of aluminum ions in their tissues, allowing them to grow in acidic soils.

Distribution and Habitat

The Polygonaceae family is distributed throughout the world, with members found on every continent except Antarctica. Many species are native to temperate climates, particularly in the northern hemisphere, while others are adapted to arid or tropical regions.

Species of Polygonaceae can be found growing in a range of habitats such as deserts, grasslands, wetlands, and forests. They are often adapted to specific environmental conditions, such as saltwater marshes, rocky hillsides, or high mountain meadows.

Some notable genera of Polygonaceae include Rheum, which is native to Asia; Rumex, which is distributed worldwide in temperate and subtropical regions; and Fallopia, which includes some invasive species such as Japanese knotweed that have spread to many parts of the world.

Overall, the diversity of habitats in which this family can be found makes it an important component of many ecosystems around the world.

Economic and Ecological Importance

The Polygonaceae family is significant both ecologically and economically. Many species within this family are edible, including buckwheat (Fagopyrum esculentum) and rhubarb (Rheum rhabarbarum). Buckwheat is commonly used in flour or noodle production, while rhubarb is often used in jams and desserts.

In addition to being a food source for humans, some species of Polygonaceae also provide important habitat and food sources for wildlife. For example, the leaves and stems of knotweed (Fallopia japonica) are an important food source for deer and other browsing animals.

Many species of Polygonaceae have medicinal uses as well. For instance, rhubarb has been used as a laxative for centuries, while extracts from various species are believed to have antiviral, antimicrobial, or anti- properties.

Overall, the diversity of ecological roles played by members of the Polygonaceae family makes it an important component of many ecosystems around the world, while the economic importance of some species has led to their cultivation and widespread use in human societies.

Notable Species

Some notable species within the Polygonaceae family include:

  • Buckwheat (Fagopyrum esculentum): A herbaceous plant that is cultivated for its edible seeds, which can be used to make flour or noodles. Buckwheat is also used as a cover crop and in crop rotation systems.

  • Rhubarb (Rheum rhabarbarum): A perennial plant that is cultivated for its edible leaf stalks, which are commonly used in desserts and jams. Rhubarb has also been used medicinally as a laxative for centuries.

  • Knotweed (Fallopia japonica): An invasive plant species that is native to eastern Asia but has spread to many parts of the world. Knotweed is known for its rapid growth and ability to outcompete other vegetation. It is considered a highly invasive species in many areas.

  • Smartweed (Persicaria spp.): A genus of herbaceous plants that are often found growing in wetland habitats. Many species of smartweed have medicinal properties, including Persicaria hydropiper, which is used to treat inflammation and fever.

  • Dock (Rumex spp.): A genus of perennial plants that are found in temperate regions around the world. Dock leaves are often used topically to relieve skin irritation caused by stinging nettle or insects.

  • Sorrel (Oxalis spp.): A genus of plants that includes both annual and perennial species. Many sorrel species are cultivated for their edible leaves, which have a tart, lemony flavor. In some cultures, sorrel is used as an ingredient in soups or stews.

These species are just a few examples of the diverse range of plants found within the Polygonaceae family.