Hamamelidaceae, commonly referred to as thewitch-hazel family, is afamily offlowering plants in the orderSaxifragales. The clade consists ofshrubs and smalltrees positioned within the woody clade of the core Saxifragales. An earlier system, theCronquist system, recognized Hamamelidaceae in theHamamelidales order.
The Hamamelidaceae are distinguishable from other families in the Saxifragales due to the range of floral characteristics that are generally uniform though all genera. Uniform characteristics includestipules borne on stems with leaves often 2-ranked.[3] Genera usually have a twocarpelgynoecium, although some species show variation. Other characteristics include a multicellularstigma, with shallow papillae or ridges.[4]
Anther structure and the modes of opening are considered to be one of the most important features in the systematics and evolution of hamamelids. The anthers in Hamamelids are on average shorter than in other families in the Saxifragales.[3] The anther valve openings are unique pleismorphic features that contrast with the simple longitudinal slits of the anthers in the upper Hamamelidae where the pollen is predominantly wind-driven.[5]
The three types of anthers found in the Hamamelidaceae are:
Type 1) The theca (or sheath of anther) opens like a window with two wings; a common anther type.[5]
Type 2) There is one valve opening to reveal two pollen sacs. Five genera in the Hamamelidoideae subfamily, confined to the Southern Hemisphere (Trichcladus,Dicoryphe,Ostrearia,Neostrearia,Noahdendron) are known to have this anther type.[5]
Type 3) One valve opens a wing of anther tissue towards the center of the flower revealing one pollen sac. The two genera,Exbucklandia andHamamelis are known to have this anther type.[5]
Plants of the Hamamelidaceae have stickypollen, which may have influenced the type of pollination that is seen in this family. Pollination is predominantly via insects or wind. However, the insect-pollinated genusDisanthus has been known to wind-pollinate (although inefficiently) in the event pollinators do not visit its flowers.[6] The genusRhodoleia is unique because it is bird-pollinated.[5][3][7]
The pollen structure in the lower Hamamelidae is relatively uniform. The pollen patterns aretricolpate[5][3] with reticulateexines.
The petals of the Hamamelidaceae are generally narrow and ribbon-like. The exceptions are the generaCorylopsis andRhodoleia, which havespathulate or circular-like petals.[5]
The flowers of Hamamelidaceae are mostly bisexual with perianth parts, which mature to fruits arranged in spikes, racemes or nonglobose heads.[5][3]
The anemophilous groups within the Hamamelidaceae are oftenandromonoecious. Self-incompatibility is common, but self-compatibility occurs in some genera such asHamamelis.[5]
The fossil record dates from theEocene.[8] Hamamelidaceae was established byBrown in 1818[1] as the Hamamelideae, including four genera.[9] Thephylogenetic relationship of the Hamamelidaceae have been revisited several times since the first comprehensive classification of the family in 1930.[10] This was clarified in 1998 by themolecular phylogenetic work of theAngiosperm Phylogeny Group (APG) which placed the family within theeudicotorderSaxifragales. In doing so, it separated one of the existing subfamilies, the Altingioideae, which formed thebasal group, into its own family within the order, theAltingiaceae.[11]
The infrafamilial classification of the Hamamelidaceae has been controversial, and has undergone a number of revisions based on morphology, the best known of which are those of Harms (1930)[10] and Endress (1989).[5][14][15]
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,[14][17][15][22] although some researchers[16] do not support this. Strong support for making Altingioideae a family has been recognized by textbooks[3] and theAngiosperm Phylogeny Group. Research continues to resolve the deep relationships of the subfamilies within the Hamamelidaceae by incorporating whole or fragmentary fossil evidence.[18][20]
Hamamelidaceae contains 27-30 genera and 80-140 species distributed among five to sixsubfamilies. The subfamilies are Exbucklandioideae, Rhodoleioideae, Mytilarioideae, Disanthoideae, Hamamelidoideae, and Altingioideae, which has been elevated to a familyAltingiaceae in some recent treatments.[3] Many of the subfamilies aremonotypic 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 andmolecular phylogenetic studies.[2][23][3][22][24]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:[9]
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:[25]
The Hamamelidaceae were widely distributed in the Northern Hemisphere during theUpper Cretaceous and earlyTertiary.[5][18]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 othergenera 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).[27]
The largest subfamily, the Hamamelidoideae, is now distributed inNorth America and western and eastern Asia. The Hamamelidoideae subtribe Dicoryphinae is now restricted to the African (includingMadagascar andComores) andAustralian continents.[27][4][14]Disanthoideae and Rhodoleioideae are now restricted to southern China and the Caucasus region.[27] Mytilarioideae is restricted to eastern Asia.Altingioideae is now restricted to eastern Asia and western Asia and North America between centralMexico andBelize.[27][23]
^abcdefghJudd, W.S., Campbell, C.S., Kellogg, E.A., Stevens, P.F. & Donoghue, M.J. 2010. "Plant Systematics: A Phylogenetic Approach, 3rd ed.". In [eds.],Plant Systematics: A Phylogenetic Approach, 3rd ed. In [eds.]. Sinauer Associates, Inc., Massachusetts.
^abEndress, P. K. (1989). "Aspects of evolutionary differentiation of the Hamamelidaceae and the Lower Hamamelididae".Plant Systematics and Evolution.162 (1–4):193–211.doi:10.1007/BF00936917.S2CID45506515.
^Xiao, Y.-A.; Neog, B.; Xiao, Y.-H.; Li, X.-H.; Liu, J.-C. & He, P. (2009). "Pollination biology ofDisanthus cercidifolius var. longipes, an endemic and endangered plant in China".Biologia.64 (4):731–736.doi:10.2478/s11756-009-0122-7.
^Gu, L.; Z. Luo; D. Zhang & S. S. Renner (2010). "Passerine pollination of Rhodoleia championii (Hamamelidaceae) in subtropical China".Biotropica.42 (3):336–341.doi:10.1111/j.1744-7429.2009.00585.x.
^abQiu, Y.-L.; et al. (1998). "Phylogenetics of the Hamamelidae and their allies: parsimony analyses of nucleotide sequences of the plastid gene rbcL".International Journal of Plant Sciences.159 (6):891–905.doi:10.1086/297611.
^abcMagallon, S.; Herendeen, P.S. & Crane, P.R. (2001). "Androdecidua endressii gen. et sp. nov., from the Late Cretaceous of Georgia (United States): Further Floral Diversity in Hamamelidoideae (Hamamelidaceae)".International Journal of Plant Sciences.162 (4):963–983.doi:10.1086/320770.
^Chang, H.T. (1979). "Hamamelidaceae".Flora Reipublicae Popularis Sinicae.35:36–116.
^abMagallon, S. (2007). "From fossils to molecules: Phylogeny and the core eudicot floral groundplan in Hamamelidoideae (Hamamelidaceae, Saxifragales)".Systematic Botany.32 (2):317–347.doi:10.1600/036364407781179617.S2CID85920898.
^Huang, G.L. (1986). "Comparative anatomical studies on the woods of the Hamamelidaceae in China".Sunyatsenia.1:24–26.
^abPan, K.-Y.; Lu, A.-M. & Wen, J. (1990). "Characters of Leaf Epidermis in Hamamelidaceae (s. l.)".Sunyatsenia.28:10–26.
^Takhtajan, A. 1997. "Diversity and classification of flowering plants". In [eds.],Diversity and classification of flowering plants. Columbia University Press, New York.
Li, Jianhua; Bogle, A. Linn; Klein, Anita S. (July 1999). "Phylogenetic relationships of the Hamamelidaceae inferred from sequences of internal transcribed spacers (ITS) of nuclear ribosomal DNA".American Journal of Botany.86 (7):1027–1037.doi:10.2307/2656620.JSTOR2656620.PMID10406726.
Li, Jianhua; Bogle, A. Linn (2001). "A new suprageneric classification system of the Hamamelidoideae based on morphology and sequences of nuclear and chloroplast DNA".Harvard Papers in Botany.5 (2):499–515.ISSN1043-4534.JSTOR41761618.
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