Sunday, September 09, 2007

Rudbeckia hirta

Black-eyed Susan (R. hirta)
General Botanical Characteristics: Black-eyed Susan is a native, warm-season, annual, biennial or short-lived perennial forb. It has one to a few stems 12 to 40 inches (0.3-1.0 m) tall, which are erect and sometimes sparingly branched. The lower leaves are 2 to 6 inches (5-15 cm) long, alternate and petioled. The upper leaves are mostly sessile. The inflorescences are few to many flower heads on peduncles 2 to 8 inches (5-20 cm) long. The fruit is an achene 0.06 inches (1.5 mm) long; there is no pappus. Black-eyed Susan has a taproot or a cluster of fibrous roots. It is a mycorrhizal species.
Sometimes flower stalks will appear in the first summer, but typically black-eyed Susan blooms from June to September of the second year. After flowering and seed maturation, the plants die. The seed is very small (1,746,000 per pound) and black, about 2 mm long and 0.5 mm in diameter.
Adaptation and Distribution: Black-eyed Susan is naturalized in most of the states east of Kansas and the bordering areas of Canada. It is adapted throughout the Northeast on soils with a drainage classification range from well-drained to somewhat poorly drained. It will perform acceptably on droughty soils during years with average or above rainfall, but best growth is achieved on sandy, well drained sites. It is winter hardy in areas where low temperatures are between -30 ° and -20 °F.
Uses: Erosion control: Black-eyed Susan is an important component in critical area treatment plantings along with grasses, legumes, and other forbs when used along road cuts, hillsides, and other areas subject to erosion.
Wildlife: This plant offers protection and food to several song and game birds.

Sources and further reading:
USDA Forest Service
University of Maryland, College Park (image source)

No comments: