Balsaminaceae
Christopher Noll
Balsaminaceae is well-known horticulturally by several cultivated species of Impatiens, especially I. balsamina L. (garden balsam), I. hawkeri W.Bull (New Guinea impatiens), and I. walleriana Hook.f. (impatiens). Except for a monotypic genus (Hydrocera), all other species of Balsaminaceae are in the large and florally diverse genus Impatiens, which contains approximately 1,000 species and is by far the most speciose in Africa and Asia. The floral structure of Balsaminaceae is quite complicated. The petals and lower sepal are the showy perianth parts and the lower sepal is usually modified into a nectar spur. Additionally, the stamens are fused to form a cap at the top of the pistil and are pushed off as the pistil matures, a behavior that favors cross-pollination. The fruit is a fleshy capsule which explodes at maturity, dispersing seeds elastically. The common name of “touch-me-not” for our native species derives from this mechanism.
