- Astragalus plants are perennials that can reach a maximum height of 3 feet. They are native to China, Mongolia and Korea, and have hairy stems with leaves made of at least a dozen pairs of leaflets, according to the University of Maryland Medical Center. The herb is normally obtained from 4-year-old plants. Always consult with a physician before taking an herb.
- Astragalus plants grow actively during the spring, summer and fall, according to the Natural Resources Conservation Service. It has fine green leaves and purplish flowers which produce brownish seeds. It prefers average slightly acidic soil, tolerates drought and is very hardy, withstanding temperatures as low as -38 degrees Fahrenheit. Astragalus blooms and produces its seeds in mid-summer and can only be propagated by seed. The National Center for Complementary and Alternative Medicine states that there are more than 2,000 species of the herb -- but only two, astragalus membranaceus and astragalus mongholicus are used for medicinal purposes. One species, astragalus lentiginosus, contains a substance that can cause locoism in animals, according to Blueplanetbiomes.org. A less harmful variety of milk vetch is widely grown in the United States along roadsides to prevent erosion.
- The Chinese have long used the astragalus herb in their traditional medicine, says the National Center for Complementary and Alternative Medicine. The Chinese still use it to treat chronic hepatitis and as an adjunctive cancer therapy, which means that it is used along with a primary cancer treatment. Astragalus is used to treat colds and other respiratory infections -- as well as heart disease. Its root is commonly used as extracts, capsules, in soups and teas, along with other herbs such as ginseng, licorice and anglica, according to the NCCAM.
- The National Center for Complementary and Alternative Medicine states that the evidence for using astragalus for health conditions is inconclusive, and more clinical trials involving people will need to be done. There is currently some basis to the potential benefits of astragalus for the immune system, the heart, the liver and as a supportive cancer therapy. Investigations funded by the NCCAM are ongoing to study the effects of astragalus on the human body, specifically on the immune system. No possible side effects are currently reported, as it is normally used in conjunction with other herbs. While astragalus is reported safe to use by most adults, it may interact with certain drugs used by cancer patients and by organ transplant recipients, and it may affect blood pressure and sugar levels, according to the NCCAM -- which also says that some species of astragalus have proven toxic to humans, but these are not normally found in supplements.