Hamamelis virginiana L.
Click to enlarge
Basis for Listing
Hamamelis virginiana is a fairly common forest shrub farther east, but it is quite rare in Minnesota where it reaches the northwestern periphery of its range. Extensive searches have discovered surviving plants to be clustered in only about a half dozen habitat fragments in the southeastern counties. There is concern that these fragments may not have retained the ecosystem processes that are necessary to assure the perpetuation of this species. In light of this, intensive management such as manual removal of invasive species or the creation of habitat buffers may be needed. Hamamelis virginiana was listed as a special concern species in Minnesota in 1984, however, elevating its status to threatened is currently being considered.
Hamamelis virginiana is a large shrub with multiple stems that may reach heights of 6 m (20 ft.) and diameters of 8 cm (3 in.). The branchlets are brown or gray and have stellate hairs. The bark is brown or gray-brown and rough. The leaves are simple, alternate on the stem, and deciduous. They are broadly elliptical to nearly circular in outline, 6-15 cm (2.4-5.9 in.) long and 4.5-10 cm (1.8-3.9 in.) wide, and the margins are irregularly wavy. The flowers are bisexual, 4-merous, and sessile in axillary clusters. The petals are yellow, ribbon like, and 1-2 cm (0.4-0.8 in.) long. The fruit is a woody capsule, 1-1.4 cm (0.4-0.6 in.) long that matures in autumn one year after pollination. It opens explosively and disperses seeds forcibly (Smith 2008).
Hamamelis virginiana occurs in the understory of dry to moist deciduous forests, typically with Quercus spp. (oaks), Acer saccharum (sugar maple), or Tilia americana (basswood). It easily survives and reproduces in a closed-canopy forest, but growth and flowering are reportedly increased under small canopy gaps (Hicks and Hustin 1989). These habitats are usually integral parts of large, complex forest systems that posses considerable topographic relief and varying edaphic conditions.
Biology / Life History
Hamamelis virginiana is peculiar in that the flowers open in the autumn; usually peaking about the time the leaves are falling. This may happen after the first frost, yet flying insects are still active and manage to pollinate the flowers. Although pollination occurs in the autumn, actual fertilization does not occur until the following spring (Flint 1957), so the fruits develop during the summer, like those of most spring-pollinated species. When the fruits are ripe in the autumn, they burst open, forcibly ejecting two smooth black seeds a distance of up to 10 m (33 ft.) (Meyer 1997). Most seeds remain dormant in the soil for 18 months, germinating after two winters (Gaut and Roberts 1984).
Conservation / Management
The main conservation consideration for H. virginiana is the full maintenance of ecosystem processes within its forest habitat, which may come into conflict with consumptive uses such as logging, livestock grazing, and residential development. For a number of reasons, livestock grazing in native forests is widely recognized as incompatible land management and is therefore not nearly as prevalent as in the past. However, logging and residential development seem to be increasing. They have the effect of directly reducing available habitat and at the same time increasing exotic species invasion. Rhamnus cathartica (common buckthorn) and Lonicera spp. (Eurasian bush honeysuckles) are perhaps the most destructive exotic shrubs in forest habitats, however there are a dozen additional species that also cause serious problems and that number is increasing almost every year.
Conservation Efforts in Minnesota
A relatively small population of H. virginiana is known to occur in a State Park where it is protected from commercial logging and residential development. There is another cluster of records on state-owned forestland that is managed for timber production. No effort has been made to assess the conservation needs of any of these sites.
De Steven, D. 1983. Reproductive consequences of insect seed predation in Hamamelis virginiana. Ecology 64:89-98.
Flint, F. F. 1957. Megasporogenesis and megagametogenesis in Hamamelis virginiana L. Virginia Journal of Science 8:185-89.
Fulling, E. H. 1953. American witch hazel: history, nomenclature and modern utilization. Economic Botany 7:359-381.
Gaut, P. C., and J. N. Roberts. 1984. Hamamelis seed germination. Plant Propagation 34:334-342.
Hicks, D. J., and D. L. Hustin. 1989. Response of Hamamelis virginiana L. to canopy gaps in a Pennsylvania oak forest. American Midland Naturalist 121:200-204.
Meyer, F. G. 1997. Hamamelis. Pages 363-365 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 3. Oxford University Press, New York, New York.
Smith, W. R. 2008. Trees and shrubs of Minnesota. University of Minnesota Press, Minneapolis. 703 pp.