Scutellaria belongs to the plant genus Labiatae. These are herbaceous, suffruticose, or shrubby plants that are cultivated for ornamental use. They have whole or pinnatifid leaves and bell-shaped flowers, with straight or curved tubes, which are purplish, pinkish, or yellow.
There are two types of skullcap: American Skullcap (Scutellaria lateriflora) and Chinese Skullcap (Scutellaria baicalensis). The two types are used to treat different conditions and therefore it is not possible to substitute one for the other.
Skullcap is native to North America, but has recently been widely cultivated in Europe and other parts of the world. It has been used for more than 200 years as a mild relaxant and as a treatment for anxiety, tension, and seizures. Studies show that the American skullcap possesses considerable antioxidant effects and may help protect against neurological disorders such as Alzheimer’s disease, Parkinson’s disease, anxiety, and depression. There is also evidence to suggest that American skullcap may inhibit food allergies. Other herbs are currently used for this purpose, such as Valerian, but skullcap continues to be used in some preparations in combination with other calming herbs.
Most studies conducted on skullcap have examined Chinese skullcap. Originating in China and parts of Russia, Chinese skullcap has been used in traditional Chinese medicine to treat allergies, infections, inflammation, cancer, as well as headaches. It may also exhibit antifungal and antiviral effects. Several animal research studies suggest that Chinese skullcap may help reduce the symptoms of diabetes and hypertension (high blood pressure), but research has yet to establish its validity in humans. The same applies to its use for some of its anti-cancer properties, which have been shown in laboratory and animal studies. However, evidence is still warranted in humans.
Studies have shown anti-inflammatory activity of skullcap similar to that of NSAIDs (non-steroidal anti-inflammatory drugs), but without the side effects on the stomach. The reduction in the inflammatory response is due to the presence of flavones contained in the root of Skullcap baicalensis. Several studies have demonstrated the positive effects of baicalin on osteoarthritis. This is a degenerative disease that affects joints by consuming the extracellular matrix of cartilage.  Researchers’ findings are very promising and suggest that baicalin may be a valuable resource in treating osteoarthritis.
Chinese skullcap is related to and resembles American skullcap, but it is a different plant. Its single stems blossom into a profusion of blue or purple flowers.
American skullcap derives its name from its small blue and violet flowers whose outer whorl resembles the outer spiral of a skullcap. It is a long-stemmed, heavily branched plant that can grow to a height of about 1.20 metres, and blooms in July. It grows wild in forests and meadows.
The Chinese skullcap is botanically similar to the American variety, but is nevertheless a different plant.
The leaves of American skullcap are used medicinally. They are typically harvested in June from a three-to-four-year-old plant. In Chinese skullcap however, it is the roots that are used for medical purposes.

(Source: Mount Sinai Hospital)