Hamamelidaceae R.Br.

Gemma Bramley, Anna Trias-Blasi & Richard Wilford (2023). The Kew Temperate Plant Families Identification Handbook. Kew Publishing Royal Botanic Gardens, Kew

Recognition

Characters of similar families: Altingiaceae: trees; monoecious; stipules usually present, borne on petiole; leaf blade palmately lobed (entire in subtropical species); flowers unisexual; sepals and petals absent; styles persistent in fruit; infructescences globose, styles often indurate and spiny in fruit. Cercidiphyllaceae: trees; dioecious; leaves opposite, oval; flowers in terminal heads, 16–35 stamens; perianth absent; stamens red; fruit a small follicle. Tropical groups have persistent leaves with mainly brochidodromous venation, whereas temperate genera mostly have deciduous leaves with craspedodromous venation.

Morphology General Habit

Habit, trees or shrubs, deciduous, or evergreen

Morphology General Buds

Buds perulate or naked

Morphology Leaves Stipules

Stipules small, deciduous, borne on stem, usually paired (solitary in Mytilaria)

Morphology Leaves

Leaves simple, petiolate, rarely spiral, opposite, sometimes subopposite, simple, tricuspidate or lobed; venation camptodromous or actinodromous and brochidodromous or craspedodromous; margin entire or dentate; indumentum stellate or tufted hairs

Morphology Reproductive morphology Inflorescences

Inflorescences spikes, heads, racemes or (condensed) thyrses or panicles

Morphology Reproductive morphology Flowers

Flowers actinomorphic, rarely zygomorphic (Rhodoleia); mostly yellow, white, greenish or red; bisexual, andromonoecious or unisexual; perianth reduced or absent; sepals absent or 4–5–(10), imbricate or persistent; petals absent or 4 or 5, often ribbon-like and circinate in bud; stamens (1)–2–5 or numerous, alternipetalous; anthers basifixed, dehiscing by valves or by a longitudinal slit; ovary 1(–2), inferior to superior, carpels (1)–2, often free at apex, 2(–3) locules, styles 2, stigmas 2 sometimes decurrent

Morphology Reproductive morphology Fruits

Fruit dehiscent capsules, endocarp woody or leathery

Morphology Reproductive morphology Seeds

Seeds 1 or more per carpel, dispersed by ballistic ejection (other than Rhodoleia), mostly hard and black.

Distribution

Hamamelidaceae contains 26 genera (8 being monotypic) and ca. 100 species. The family has a wide but scattered and relict distribution, with the greatest diversity in E Asia.

Note

Trees or shrubs. Leaves with stellate indumentum; stipules borne on stem, usually paired. Inflorescence a spike or head, usually compact; perianth reduced or absent. Fruit a woody capsule, dehiscent; seed dispersal ballistic.

Description Author

Harry Baldwin & Tony Kirkham

Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://creativecommons.org/licenses/by/3.0

Morphology General Habit

Trees or shrubs, evergreen, indumentum of mostly sclerified stellate or tufted trichomes

Morphology Leaves

Leaves alternate, distichous simple, petiolate, margins entire; venation pinnate, campylodromous, secondary veins terminating in the teeth or three-veined at base (Matudaea Lundell); stipules small, deciduous, distinct, scarious, borne on stem adjacent to petiole

Morphology Reproductive morphology Inflorescences

Inflorescences terminal and axillary, dense spherical heads or racemes of unisexual rudimentary flowers

Morphology Reproductive morphology Flowers

Flowers small, hermaphroditic, unisexual or andromonoecious; sepals absent or rarely 5; petals absent; stamens 2-numerous often with prolonged connective, anthers basifixed, covered by stellate trichomes, mostly dehiscing by valves or by a longitudinal slit; ovary inferior, partially inferior or superior Matudaea, carpels 2, syncarpous, often free at apex, bi-locular, styles 2, stigma 2, decurrent

Morphology Reproductive morphology Fruits

Fruit woody, ovoid (stalked and sessile in same infructescence) capsular, often aggregate, exocarps leathery, endocarp bony

Morphology Reproductive morphology Seeds

Seeds one per carpel, dispersed by ballistic ejection, hard and black or brown, smooth, resemble pine nuts when dry.

Note

Notes on delimitation: Placed in the Saxifragales, closely related to Daphniphylaceae and Cercidiphyllaceae (APG2, 2003). Forms an order along with the Neotropical Crassulaceae, Grossulariaceae, and Saxifragaceae, plus Iteaceae and Pterostemonaceae. Considered to be part of the woody clade along with the Neotropical Altingiaceae and Haloragaceaesensu lato (expanded to include Tetracarpaceae, Penthoraceae and Aphanopetalum Endl.) plus the Asian, Cercidiphyllaceae and Daphniphyllaceae. (Jian et al 2008). Number of genera: Two: Matudaea and  Molinadendron.

Distribution

Mexico to Colombia. Cool upland regions, wet mixed forest. Molinadendron Endress (includes Neotropical Distylium Sieb. & Zucc.) with three Neotropical species: M. guatemalense (Radlk. ex Harms) P.K. Endress, M. hondurense (Standl.) P.K. Endress and M. sinaloense (Standl. & Gentry) P.K. Endress distributed from Costa Rica to Mexico (Sinaloa). Matudaea Lundell with two species: M. trinerva Lundell and M. hirsuta Lundell occurring in Honduras and through to Central Mexico. Native.

Diagnostic

Key differences from similar families: Altingiaceae (Hamamelidaceae p.p.) represented in the Neotropics by Liquidamberstyraciflua L. are deciduous with leaves spirally arranged and contain resin canals in their bark. Distinguishing characters (always present): Evergreen plants with stellateindumentum. Leaves alternatedistichous, stipulate, petiolate, with entire margins. Compacted inflorescence of small, rudimentary flowers, perianth absent, anthers basifixed, gynoecium 2-merous. Fruit a woodycapsule or often aggregate of several flowers. Seeds dispersed by ballistic ejection. Molinadendron Endress: Evergreen trees or shrubs. Branches with 1-2 prophylls. Conspicuous galls sometimes present. Petals absent. Carpels with 1 ovule. Stigmas (2), large and decurrent. Matudaea Lundell: Evergreen trees. Multicellular glandular hairs in the blade margin of primary leaves, stipules and bracts. Branches with 2 prophylls. Leaves triplinerved. Inflorescences condensed panicles or botryoids (each axis terminated by a flower). Flowers bisexual. Sepals absent. Petals absent. 2 fused bracts subtend the individual flower. Stamens 12-24, polyandrous. Anthers opening by 2 valves. Ovarysuperior. Carpels with 1 ovule. Large, decurrentstigma.

Hamamelidaceae, B. Verdcourt. Flora of Tropical East Africa. 1971

Morphology General Habit

Evergreen or deciduous trees or shrubs, often with stellate indumentum

Morphology Leaves

Leaves alternate or less often opposite, simple, but often pinnatifid or palmatilobed, entire or serrate (the teeth sometimes glandular), usually stipulate; stipules mostly paired, persistent or more usually deciduous

Morphology Reproductive morphology Inflorescences

Inflorescences terminal or axillary, racemose, often spicate or capitate, sometimes so densely packed that the flowers are almost joined; bracts and bracteoles often present, the former sometimes forming a coloured involucre

Morphology Reproductive morphology Flowers

Flowers small to large, regular or rarely irregular, hermaphrodite or unisexual, hypogynous to perigynous, rarely without a perianth

Morphology Reproductive morphology Flowers Calyx

Calyx-tube variously shaped, usually ± adnate to the ovary; lobes (3–)5(–7), imbricate or valvate

Morphology Reproductive morphology Flowers Corolla

Petals 4–5 or more, sometimes absent in ? flowers, free, imbricate or valvate, rarely circinate, mostly linear-spathulate or obovate

Morphology Reproductive morphology Flowers Androecium

Stamens 4–5(–25), rarely fewer, as many as and alternating with the petals, arranged in one series; staminodes sometimes present; filaments free, sometimes thickened and shorter than the anthers; anthers 2-thecous, opening lengthwise or by valves, the connective sometimes projecting to form a beak

Morphology Reproductive morphology Flowers Nectaries

Disc usually absent, when present annular or composed of separate glands

Morphology Reproductive morphology Flowers Gynoecium

Ovary inferior, half-inferior or rarely superior, (l–)2(–3)-locular, the carpels sometimes free at the apex; ovules 1 or more in each cell, apical or anatropous, pendulous; placentation axile; styles 2, subulate, usually free, often recurved, sometimes persistent, the stigmas terminal or lateral

Morphology Reproductive morphology Fruits

Fruit a woody loculicidal or septicidal capsule, with leathery exocarp and bony endocarp, often appearing apically 4-valved

Morphology Reproductive morphology Seeds

Seeds 1–many, sometimes winged, with thin endosperm; embryo straight

Hamamelidaceae, E. J. Mendes and M. P. Vidigal. Flora Zambesiaca 4. 1978

Morphology General Habit

Trees and shrubs, often with stellate indumentum

Morphology Leaves

Leaves alternate or less often opposite, deciduous or persistent, simple, entire or not, pinnately or palmately nerved; stipules mostly paired, often deciduous

Morphology Reproductive morphology Inflorescences

Inflorescences racemose, often spicate or capitate, sometimes very dense, terminal or axillary; bracts and bracteoles often present

Morphology Reproductive morphology Flowers

Flowers bisexual or unisexual, actinomorphic or rarely zygomorphic, rarely without a perianth

Morphology Reproductive morphology Flowers Calyx

Calyx-tube ± adnate to the base of the gynoecium; calyx-lobes 4–5 or more, imbricate or valvate

Morphology Reproductive morphology Flowers Corolla

Petals 4–5 or more, sometimes absent in female flowers, free, imbricate or valvate, rarely circinnate

Morphology Reproductive morphology Flowers Androecium

Stamens 1-seriate, usually as many as and alternating with the petals, rarely fewer or indefinite, perigynous; filaments free; anthers 2-locular, opening lengthwise by slits or by valves; the connective often produced; staminodes sometimes present, alternating with the stamens

Morphology Reproductive morphology Flowers Nectaries

Disk absent or annular or of separate glands

Morphology Reproductive morphology Flowers Gynoecium

Ovary inferior or nearly so, rarely sub-superior, (l)2(3)-carpellary and -locular; carpels often free at the apex; styles subulate, free, often recurved and persistent; stigmas terminal or lateral; ovules 1-many in each loculus, axillary, pendulous

Morphology Reproductive morphology Fruits

Fruit a woody capsule, loculicidal or septicidal

Morphology Reproductive morphology Seeds

Seeds mostly 1 per loculus, sometimes winged; endosperm thin; embryo straight