Hamamelidaceae, commonly referred to as the witch-hazel family, is a family of flowering plants in the order Saxifragales. The clade consists of shrubs and small trees positioned within the woody clade of the core Saxifragales. An earlier system, the Cronquist system, recognized Hamamelidaceae in the Hamamelidales order.

Description

The Hamamelidaceae are distinguishable from other families in the Saxifragales due to the range of floral characteristics that are generally uniform through all genera. Uniform characteristics include stipules borne on stems with leaves often 2-ranked. The genus Rhodoleia is unique because it is bird-pollinated.

The pollen structure in the lower Hamamelidae is relatively uniform. The pollen patterns are tricolpate and have recognized the separation of the Rhodoleioideae and Disanthoideae subfamily and newly erected Mytilarioideae.

The relationships between Exbucklandioideae and the other subfamilies have proven controversial. The unresolved monophyly of Exbucklandioideae and the clades of Disanthoideae, Rhodoleioideae, Exbucklandioideae or even Mytilarioideae being a sister clade to Hamamelidoideae may have been a result of differing DNA methodologies researchers have used to produce phylogenetic trees and the inclusion or exclusion of certain genera used as outgroups in their analyses. However, the sister relationship of Disanthoideae and Hamamelidoideae has been well supported, Many of the subfamilies are monotypic and the majority of the species lie within the Hamamelidoideae, which has 22 genera.

The long-standing question of whether Altingioideae should be a separate family has been assessed and supported by morphological and molecular phylogenetic studies.

The resulting subfamilial structure was eventually resolved in a series of molecular studies in the late 1990s, resulting in five distinct subfamilies, the majority of the genera residing in the nominative subfamily, Hamamelidoideae:

;Subfamilies (number of genera)

  • Exbucklandioideae (1 genus; Exbucklandia)
  • Rhodoleioideae (1 genus; Rhodoleia)
  • Mytilarioideae (2 genera; Mytilaria, Chunia)
  • Disanthoideae (1 genus; Disanthus)
  • Hamamelidoideae (22 genera; see Tribes below)

Tribes

The relatively large size of subfamily Hamamelidoideae and its further subdivision into tribes has also been a matter of study and controversy. Six tribes are now recognized. The revised structure has greatly reduced Hamamelideae to a monotypic taxon, which had previously been further divided into subtribes:

  • Corylopsideae (1 genus; Corylopsis)
  • Dicorypheae (5 genera; Dicoryphe, Trichocladus, Neostrearia, Noahdendron, Ostrearia)
  • Eustigmateae (4 genera; Eustigma, Fortunearia, Sinowilsonia, Molinadendron)
  • Fothergilleae (7 genera; Fothergilla, Parrotiopsis, Parrotia, Shaniodendron, Sycopsis, Distylium, Distyliopsis)
  • Hamamelideae (1 genus; Hamamelis)
  • Loropetaleae (4 genera; Loropetalum (including Tetrathyrium), Maingaya, Embolanthera, Matudaea)

Genera

27 genera are accepted.

  • Chunia – 1 species, Hainan and Vietnam
  • Corylopsis – winter-hazel; about 30 species, east Asia
  • Dicoryphe – 13 species, Madagascar and Mayotte
  • Disanthus – 1 species, east Asia
  • Distyliopsis – 6 species, southern China to New Guinea
  • Distylium , 16 species, east Asia and Himalayas
  • Embolanthera – 2 species, Philippines and Vietnam
  • Eustigma – 4 species, China, Indochina, and Taiwan
  • Exbucklandia – 3 species, Assam, China, and southeast Asia
  • Fortunearia – 1 species, eastern China
  • Fothergilla – fothergilla; 3 species, southeastern United States)
  • Hamamelis – witch-hazel; 4 species, eastern North America and east Asia
  • †Langeria – Eocene, 1 species
  • Loropetalum – three species, east Asia
  • Maingaya – 1 species, Peninsular Malaysia and Thailand
  • Matudaea – 2 species, southern Mexico, Central America, and Colombia
  • Molinadendron – 3 species, northwestern Mexico and central America
  • Mytilaria – 1 species, southern China, Laos, and Vietnam
  • Neostrearia – 1 species, northeastern Queensland
  • Noahdendron – 1 species, northeastern Queensland
  • Ostrearia – 1 species, Queensland
  • Parrotia – Ironwoods; 2 species, disjunct in southwest Asia and eastern China
  • Parrotiopsis – 1 species, Himalaya
  • Quangnamia – 1 species, Vietnam
  • Rhodoleia – 6 species, southeast Asia
  • Sinowilsonia – 1 species, western China
  • Sycopsis – 3 species, China and Assam
  • Trichocladus – 4 species, eastern and southern Africa

Distribution and habitat

The Hamamelidaceae were widely distributed in the Northern Hemisphere during the Upper Cretaceous and early Tertiary.

Quaternary glaciation across the Northern Hemisphere caused the extinction of numerous species and the restricted distribution of others. Hamamelidaceae were obliterated from Europe along with numerous other genera of plants that were unable to escape the ice sheets due to geography (the Mediterranean Sea and Alps forming barriers that did not exist in North America and Asia).

The largest subfamily, the Hamamelidoideae, is now distributed in North America and western and eastern Asia. The Hamamelidoideae subtribe Dicoryphinae is now restricted to the African (including Madagascar and Comores) and Australian continents.

Disanthoideae and Rhodoleioideae are now restricted to southern China and the Caucasus region.

References

Bibliography

Books and theses

Articles

;APG

Websites

  • (see also Angiosperm Phylogeny Website)
  • Hamamelidaceae in L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants.