Hamamelis virginiana L. (Hamamelidaceae).
Hamamelis comprises four woody species; two in eastern North America and two in East Asia. Genera with similar disjunct distributions are described as Tertiary relicts; they are the remnants of the plants that made up the forests that covered the Northern Hemisphere 15-65 million years ago. Witch hazel is one of the American shrubby species, producing clusters of yellow, faintly-scented, spidery-looking flowers in late-autumn and winter. The fruits are explosive, woody capsules which are capable of flinging the shiny, black seeds up to 10 m from the mother plant; the fruits take one year to mature.
All members of the genus, except witch hazel, flower during spring and into early summer. This raises the question of why witch hazel, which is insect-pollinated, should have evolved to flower during periods when temperatures are likely to be low and insect pollinators rare. Natural witch hazel populations are highly floriferous, the nectar of the flowers has characteristics which make it attractive to bee and fly pollinators. In its natural range, despite pollinators being rare at the end of the season, witch hazel flowers are at an advantage; they avoid competing for pollinators with the species' close relative Hamamelis vernalis, which flowers at the beginning of the year.
All Hamamelis species have attracted horticulturalists' attention. Witch hazel was introduced to Britain and Europe as a garden plant, in 1736, from its native American distribution, through the collaboration between the colonial collector John Bartram and English cloth merchant Peter Collinson. Bartram and Collinson's collaboration produced hundreds of new American plants for English gardens. Englishman Mark Catesby, another of the great eighteenth-century promoters of American plants in English gardens and author of Hortus Europae Americanus (1767), received living witch hazel plants at Christmas 1743 'as then full of blossoms, as it has annually been about the same time ever since: it is a hardy shrub, and is proof against the severest cold'. However, today, as a garden plant witch hazel is surpassed by its Asian cousins.
'Witch' has nothing to do with broomsticks and cats; it derives from the Old English meaning 'pliant', a reference to the shrub's flexible twigs. Witch hazel decoctions are used as astringents and for the treatment of inflammation and dermatological conditions in the introduced range, as they had been since Pre-Columbian times in the native range. There is some evidence witch hazel contains tannins that are toxic to colon cancer cells.
Anderson GJ, Hill JD 2002. Many to flower, few to fruit: the reproductive biology of Hamamelis virginiana (Hamamelidaceae). American Journal of Botany 89, 67-78.
Wulf A 2008. The brother gardeners. Botany, empire and the birth of an obsession. William Heinemann.