Leaf: Evergreen, opposite, compound with 2 small (1/4 to inch long) leaflets, generally elliptical but often curved, yellow green to green and appear varnished, fragrant particularly after a rain.
Flower: Five, bright yellow, twisted sepals, about 1 to 1 inches across, occur at the ends of the twigs, appearing in spring and scattered throughout the year. Fruit: Capsule (1/4 inch), covered in long, stiff white hairs.

Twig: Slender, light gray to reddish brown, each node is ringed in a darker color and is slightly swollen.

Bark: Initially smooth and gray, eventually becomes darker and splits into shallow fissures and flat plates.

Form: A multi-stemmed shrub commonly up to 4 feet tall but may reach 15 feet, generally a round shape. Spreads by cloning itself along the edges of the plant often resulting in a circular pattern of "cloned" plants.
Historical or traditional use (may or may not be supported by scientific studies)
Chaparral has been used for thousands of years by Native Americans for a variety of purposes. It has been employed primarily in tea form to help with cramping pains, joint pains, and allergic problems, as well as to eliminate parasites.  Externally it has been applied to reduce inflammation and pain, and to promote healing of minor wounds.
Active constituents
The major lignan in chaparral, known as nordihydroguaiaretic acid (NDGA) is a potent antioxidant and was thought by some scientists to be a potential cancer treatment. In a rat study, NDGA and a leaf extract of a South American subspecies of chaparral were found to exert an antitumor effect. However, one report suggests that NDGA may stimulate further growth of tumors in cancer patients. Clinical trials, therefore, are still needed to establish whether chaparral is a safe and effective treatment for people with cancer.

Other reported effects for chaparral include anti-inflammatory properties as well as antimicrobial actions in test tubes. These actions have note been established in human clinical trials.
How much is usually taken?
A tea can be prepared by steeping 1 teaspoon (approximately 5 grams) of leaves and flowers in 1 cup (250 ml) of hot water for ten to fifteen minutes. People should drink three cups per day for a maximum of two weeks unless under the care of a physician expert in the use of botanical medicines. Alternatively, 0.51 ml of tincture can be taken three times per day. Topically, cloths can be soaked in oil preparations or tea of chaparral and applied several times per day (with heat if helpful) over the affected area. Capsules of chaparral should be avoided.

Are there any side effects or interactions?
There have been sporadic reports of people developing liver or kidney problems after taking chaparral, particularly in capsules. Almost all of these cases involved either the use of capsules or excessive amounts of tea. Some of these cases were people with established liver disease prior to using the herb. Tea and tincture of chaparral have an extremely strong taste considered disagreeable by most people, which restricts the amount they can tolerate before feeling nauseous. Capsules bypass this protective mechanism and should therefore be avoided. Since human studies have shown that large amounts of chaparral tea and injections of NDGA in people with cancer do not cause liver or kidney problems, it is likely the cases of toxicity represented individual reactions.

At the time of writing, there were no well-known drug interactions with chaparral.