Common St. John's Wort

Scientific Name: Hypericum perforatum
Family Name: Hypericaceae

Flower: 3/4 - 1 in. (2 - 2.5 cm.) wide, bright yellow with 5 petals.

Leaf: There are many, small leaves opposite leaves, which are 1 - 2 inches (2.5 - 5 cm.) long.

Plant: St. John's Wort grows from June to August and can reach a height of 2 ft (60 cm).

Identifying Characteristics: Common St. John's Wort can be identified by the black dots on the edge of its five yellow flower petals. These black dots are often found on the leaves as well.

Location: We found Common St. John's Wort on the side of the road that connects the Brandeis University peripheral road to T-Lot (in between the admission building and Spingold Theatre).

History and Comments: Common St. John's Wort is a native of Europe, and many people think that it possesses healing properties. Because Common St. John's Wort is the most found St. John's Wort in the United States, it is often the base of these herbal remedies. However, in both animals and humans, it can cause photodermatitis, oversensitivity to light. Common St, John's Wort is considered more of a problem in the western states, particularly California, where it is taking over open fields. Cattle graze on it, causing serious photodermatitis. St. John's Wort is so named because Europeans believed that it bloomed on Saint John's Eve, John the Baptists's birthday, June 24. For more information on Common St. John's Wort, we suggest the website:

    Unless otherwise specified, all text, photographs, and drawings are Copyright (c) by Shu-Yee Chen and Deborah Hamer 2003. No part of this page may be reproduced without prior written consent of the authors.