''Astragalus'' is a large genus of over 3,000 species of

herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...

s and small

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

s, belonging to the

legume A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock f ...

family

Fabaceae The Fabaceae or Leguminosae,International Code of Nomenc ...

and the subfamily Faboideae. It is the largest genus of plants in terms of described species. The genus is native to temperate regions of the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...

. Common names include milkvetch (most species), locoweed (in North America, some species) and goat's-thorn ( ''A. gummifer'', ''A. tragacantha''). Some pale-flowered vetches ('' Vicia'' spp.) are similar in appearance, but they are more vine-like than ''Astragalus''.

Description

Most species in the genus have

pinnately Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and in ...

compound leaves. There are annual and perennial species. The flowers are formed in clusters in a

raceme A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...

, each flower typical of the legume family, with three types of petals: banner, wings, and keel. The

calyx Calyx or calyce (plural "calyces"), from the Latin ''calix'' which itself comes from the Ancient Greek ''κάλυξ'' (''kálux'') meaning "husk" or "pod", may refer to: Biology * Calyx (anatomy), collective name for several cup-like structures ...

is tubular or bell-shaped.

Taxonomy

The genus was formally described in 1753 by Carl Linnaeus in his ''

Species Plantarum ' (Latin for "The Species of Plants") is a book by Carl Linnaeus, originally published in 1753, which lists every species of plant known at the time, classified into genera. It is the first work to consistently apply binomial names and was the ...

''. The name ''Astragalus'' is Greek, an old name for this group of plants which were believed to have a positive effect on goat milk production.

Selected species

Ecology

''Astragalus'' species are used as food plants by the larvae of some

Lepidoptera Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...

species including many case-bearing moths of the genus '' Coleophora'': '' C. cartilaginella'', '' C. colutella'', '' C. euryaula'', and '' C. onobrychiella'' feed exclusively on ''Astragalus'', '' C. astragalella'' and '' C. gallipennella'' feed exclusively on the species '' Astragalus glycyphyllos'', and '' C. hippodromica'' is limited to '' Astragalus gombo''.

Uses

Traditional medicine

Astragalus has been used in traditional Chinese medicine over centuries to treat various disorders, but there is no high-quality evidence that it is effective or safe for any medical purpose.

Phytochemicals and supplements

Extract An extract is a substance made by extracting a part of a raw material, often by using a solvent such as ethanol, oil or water. Extracts may be sold as tinctures, absolutes or in powder form. The aromatic principles of many spices, nuts, h ...

s of astragalus root include diverse

phytochemical Phytochemicals are chemical compounds produced by plants, generally to help them resist fungi, bacteria and plant virus infections, and also consumption by insects and other animals. The name comes . Some phytochemicals have been used as poisons ...

s, such as

saponin Saponins (Latin "sapon", soap + "-in", one of), also selectively referred to as triterpene glycosides, are bitter-tasting usually toxic plant-derived organic chemicals that have a foamy quality when agitated in water. They are widely distributed ...

s and isoflavone

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

s, which are purported in traditional practices to increase lactation in nursing mothers. There is no valid clinical evidence to indicate such use is effective or safe for the mother or infant.

Dietary supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...

products containing astragalus extracts may not have been adequately tested for efficacy, safety, purity or consistency. The root extracts of astragalus may be used in soups, teas or sold in capsules.

Side effects and toxicology

Although astragalus supplements are generally well tolerated, mild gastrointestinal upset, diarrhea, and allergic reactions may occur. Because astragalus may affect regulation of blood sugar and

blood pressure Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" r ...

, it may be risky for people with blood disorders, diabetes, or

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

to use it as a supplement. Astragalus may interact with prescribed drugs that suppress the immune system, such as medications used by people being treated for cancer or recovery from organ transplants. Some astragalus species can be toxic, such as those found in the United States containing the neurotoxin

swainsonine Swainsonine is an indolizidine alkaloid. It is a potent inhibitor of Golgi alpha-mannosidase II, an immunomodulator, and a potential chemotherapy drug. As a toxin in locoweed (likely its primary toxin) it also is a significant cause of economi ...

, which causes "locoweed" poisoning in animals. Some astragalus species may contain high levels of selenium, possibly causing toxicity.

Ornamental use

Several species, including ''A. alpinus'' (bluish-purple flowers), ''A. hypoglottis'' (purple flowers), and ''A. lotoides'', are grown as ornamental plants in gardens.

Notes

References

External links

''Astragalus''
– Genus of vascular plants
''Astragalus'' – Clinical summary and constituents
MSKCC Memorial Sloan Kettering Cancer Center {{Authority control Dietary supplements Fabaceae genera Forages Medicinal plants Plants used in traditional Chinese medicine Taxa named by Carl Linnaeus