Cannabaceae Martinov

Timothy Utteridge & Gemma Bramley (2020). The Kew Tropical Plant Families Identification Handbook, Second Edition. Kew Publishing Royal Botanic Gardens, Kew

Note

Leaves simple, often 3-veined and asymmetrical at base (rarely palmatecompound). Flowers unisexual (rarely bisexual), in lax axillary unisexual or bisexual cymes or clusters; ovary superior; 2 stigmas. Fruit a drupe.

Recognition

Characters of similar families: Ulmaceae: fruit mostly winged, thin flattened endocarp, leaves not 3-veined from base. Urticaceae: often herbs, flowers often asymmetrical and/or in dense heads, stigma 1. Moraceae: white latex, conspicuous stipules, flowers often asymmetrical and/or in dense heads. Malvaceae-Grewioideae: sometimes climbing, bisexual flowers, petals, many anthers, 1 stigma. Rhamnaceae: bisexual flowers, petals, conspicuous disk. Euphorbiaceae (Antidesma): stigma usually >2, leaves not 3-veined, veins looped.

Morphology General Habit

Trees, shrubs, (rarely herbs, described separately below); woody genera previously Ulmaceae; stems often zigzag or spiny, often with abscission of terminal shoot meristems above uppermost lateral bud

Morphology Leaves Stipules

Stipules soon-caducous, usually membranous, lateral free or connate

Morphology Leaves

Leaves alternate, distichous (rarely opposite), simple, often unequal-sided especially at base; lamina margins entire or toothed; venation pinnate or 3-veined from the base, often conspicuous, often looped Leaves lobed or palmate-compound

Morphology Reproductive morphology Inflorescences

Inflorescence solitary flowers or axillary unisexual or bisexual cymes or clusters

Morphology Reproductive morphology Flowers

Flowers actinomorphic, 5/4-merous, tepals in a single whorl, large conspicuous in male flowers, wind-pollinated, stamens pendulous, filaments free, anthers large ± versatile; pistillode conspicuous; stigmas 2, conspicuous, robust, diverging sometimes bilobed; ovary superior, 1(–2)-locular, ovule 1

Morphology Reproductive morphology Fruits

Fruit an achene, in Cannabis surrounded by bracteoles with resin glands and fine hairs; perianth thin, marbled; achene reticulate-veined and visible through perianth. Fruit a drupe, endocarp thick-walled (rarely exocarp winged)

Distribution

10 genera, c. 110 species. The large genus Celtis has over 65 species worldwide in tropical and temperate regions.

Ecology

Mostly in subtropical seasonal forest or upland rain forest understorey; a few in tropical evergreen lowland forest or pioneers in disturbed ground.

Description Author

C M Wilmot-Dear

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: Ulmaceae: leaves not 3-veined from base, flowers bisexual, fruit mostly winged. Urticaceae: often herbs, inflorescences congested, stamens inflexed in bud, stigma 1. Moraceae: white sap, conspicuous stipules, flowers often in dense heads. Tiliaceae: bisexual flowers, petals and sepals, many stamens, stigma 1. Rhamnaceae: bisexual flowers with conspicuous disk. Euphorbiaceae: stigma usually >2, leaves not 3-veined, veins looped. Malvaceae–Grewioideae: bisexual flowers, petals and sepals, many stamens, stigma 1.

Morphology General Habit

Trees, shrubs, rarely herbs, often spiny

Morphology Leaves Stipules

Stipules, lateral, free or fused, usually membranous, soon-caducous, rarely persistent

Morphology Leaves

Leaves petiolate, alternate, distichous, rarely opposite, simple, rarely palmate-compound (Cannabis) or lobed (Humulus), often oblique at base; margins entire to toothed; venation conspicuous, pinnate or 3–5-veined from the base; with or without cystoliths

Morphology Reproductive morphology Inflorescences

Inflorescences axillary, unisexual or bisexual cymes, racemes, clusters or female flowers solitary; plants monoecious, dioecious or polygamous

Morphology Reproductive morphology Flowers

Flowers unisexual, rarely bisexual (e.g. Celtis), actinomorphic, 4–5-merous, tepals 1 whorl, usually free and imbricate; male flowers, large, pendulous, conspicuous, wind-pollinated; stamens usually equal and opposite tepals, erect in bud, filaments free; pistillode conspicuous; female flowers sessile, stigmas 2, diverging sometimes bilobed; ovary superior, 1(–2)-locular, ovule 1; with or without staminodes

Morphology Reproductive morphology Fruits

Fruit a drupe, endocarp thick-walled, rarely exocarp winged (only in Pteroceltis) or occasionally an achene visible through the persistent, thin, marbled perianth (Cannabis and Humulus); often with persistent stigma

Morphology Reproductive morphology Seeds

Seed 1.

Distribution

A family of 9 genera and ca. 110 species. Widespread throughout tropical, subtropical and temperate regions. The large genus Celtis has 65 species in tropical and temperate zones.

Note

Leaves simple, often 3-veined and asymmetrical at base. Stipules caducous. Flowers unisexual, in lax axillary unisexual or bisexual cymes or clusters; ovary superior; 2 stigmas; fruit a drupe with persistent stigmas.

Description Author

Alison Moore & C. M. Wilmot-Dear

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, sometimes climbing, sometimes armed, monoecious, dioecious or polygamous

Morphology Leaves

Leaves alternate, usually distichous, rarely opposite, deciduous or persistent simple, margin entire to serrate, venation pinnate, usually trinerved, cystoliths present, stipules lateral-Inflorescence axillary, racemose, fasciculate or rarely reduced to only one flower

Morphology Reproductive morphology Flowers

Flowers unisexual (rarely bisexual), not showy, usually 4-5 tepals, free or connate; stamens 4-5, opposite the tepals, anthers longitudinally dehiscent; ovary superior, 2-carpels, 1-locular, locule 1-ovulate, placentation pendulous

Morphology Reproductive morphology Fruits

Fruit drupaceous; seeds rounded, embryo curved.

Note

Celtis, Trema and other taxa of woody Cannabaceae were formerly placed in Ulmaceae, subfamily Celtidoideae or Celtidaceae. Although some species of Aphananthe have secondary veins of leaves ending in the teeth, as in the Ulmaceae, it is considered that this feature evolved independently from that of Ulmaceae. The presence of unisexual flowers in Cannabaceae is an important feature for the separation from Ulmaceae. However, Trema micrantha has rare bisexual flowers, which are protogynous and sometimes functionally male. Number of genera: About 9 genera, with 4 genera and 20 species in the Neotropics: Aphananthe - A. monoica (Hemsl.) J.-F. Leroy. Celtis - C. australis L.; C. berteroana Urb.; C. brasiliensis (Gardner) Planch.; C. caudata Planch.; C. chichape (Wedd.) Miq.; C. ehrenbergiana (Klotzsch) Liebm.; C. fluminensis Carauta; C. iguanaea (Jacq.) Sarg.; C. loxensis C.C. Berg; C. pubescens (Kunth) Spreng.; C. reticulata Torr.; C. schippii Standl.; C. spinosa Spreng.; C. tala Gillies ex Planch.; C. trinervia Lam. Lozanella - L. enantiophylla (Donn. Sm.) Killip & C.V. Morton; L. permollis Killip & C.V. Morton. Trema - T. micrantha (L.) Blume; T. integerrima (Beurl.) Standl. The Celtis species are hard to identify because their flowers are very similar and the morphological characters usually cited by different authors have great variation. The taxonomy of the genus requires extensive revision, because the available studies do not adequately account for the status of the many published names. Trema micrantha is a species of wide geographical distribution and great morphological variability. Studies on its biology in two natural populations revealed that several plants do change their sex during the breeding season. These studies revealed also the occurrence of rare bisexual flowers. We accept two species for the Neotropical region but the genus, like Celtis, also needs extensive revision. Some species of Celtis provide hardwood, some are ornamental or have edible fruits. The fruits of Aphananthemonoica are also edible. Trema micrantha is an important species in the regeneration of deforested areas; its fruits are enjoyed by birds; the bark can be used to make handmade paper and its timber for manufacturing industrial paper.

Distribution

Aphananthe Planch. - Mexico, Guatemala, El Salvador, Honduras and Nicaragua. Celtis L. - Mexico, Central America and Caribbean islands to Argentina. Lozanella Greenm. - Mexico to Bolivia. Trema Lour. - Mexico, Central America and Caribbean islands to Argentina Lozanella endemic.  Alphananthe, Celtis and Trema occur in other regions and continents.

Diagnostic

Distinguishing characters (always present): Trees, or shrubs, sometimes scandent, leaves simple, alternate, generally distichous, rarely opposite (Lozanella), with stipules, cystoliths present; flowers unisexual, inconspicuous; fruit a drupe. Trees or scandent shrubs with spines (Celtis). Lozanella is very similar to Trema, but with opposite leaves and fused stipules. Key to genera of Neotropical Cannabaceae 1. Leaves opposite; stipules united, leaving a conspicuous interpetiolar scar .... Lozanella 1. Leaves alternate; stipules free or united only at their base .... 22. Monoecious plants, leaves pinnately veined, the secondary veins ending at the margin .... Aphananthe 2. Monoecious, dioecious or polygamous plants, leaves pinnately veined, usually 3-nerved at base, the secondary veins ending before the margin .... 33. Trees, unarmed; tepals induplicate-valvate in bud, stigmas 2, simple.... Trema 3. Trees or shrubs, sometimes scandent, sometimes armed; tepals imbricate in bud, stigmas 2, simple or bifurcate .... Celtis Key differences from similar families: Plants without latex, sometimes armed, never urticating (latex in all parenchymatic tissues in Moraceae or restricted to bark in Urticaceae; plants unarmed in Ulmaceae, Moraceae (except Maclura) and Urticaceae; sometimes urticating in Urticaceae). Leaves simple, alternate, distichous, rarely opposite (leaves simple or lobed, alternate, distichous, spiral or opposite in Moraceae and Urticaceae). Leaves usually 3-nervate from base (penninerved with secondary venation ending in the teeth of the margin in Ulmaceae; penninerved or palmate in Moraceae and Urticaceae). Flower unisexual with apical placentation (flower unisexual or bisexual in Ulmaceae; basal placentation in Urticaceae). Fruitdrupaceous (samara or nut in Ulmaceae; drupe or achene in Moraceae and Urticaceae, sometimes forming a compoundfruit).

Cannabaceae, C. M. Wilmot-Dear. Flora Zambesiaca 9:6. 1991

Morphology General Habit

Herbs, annual or perennial, erect or climbing, without latex

Morphology Leaves

Leaves alternate or opposite, petiolate, simple and undivided to palmately lobed or digitately compound; stipules free or fused

Morphology Reproductive morphology Inflorescences

Inflorescences numerous and axillary, flowers dioecious and wind-pollinated Female inflorescences strobilate, flowers ± sessile, crowded, tightly enclosed or loosely subtended by small or large persistent bracteoles; bracts present; perianth membranaceous, entire, investing the ovary; ovary superior, sessile, 1-locular; ovule 1, pendulous, anatropous; style terminal, short; stigmas 2, long filiform Male inflorescences paniculate, flowers with perianth uniseriate, 5-lobed, imbricate; stamens 5, opposite the perianth lobes, anthers straight, erect in bud, 2-thecous, dehiscing at first by apical pores but soon also lengthwise; pistillode absent

sex Male

Male inflorescences paniculate, flowers with perianth uniseriate, 5-lobed, imbricate; stamens 5, opposite the perianth lobes, anthers straight, erect in bud, 2-thecous, dehiscing at first by apical pores but soon also lengthwise; pistillode absent

sex Female

Female inflorescences strobilate, flowers ± sessile, crowded, tightly enclosed or loosely subtended by small or large persistent bracteoles; bracts present; perianth membranaceous, entire, investing the ovary; ovary superior, sessile, 1-locular; ovule 1, pendulous, anatropous; style terminal, short; stigmas 2, long filiform

Morphology Reproductive morphology Fruits

Fruit an achene covered by the persistent perianth; endosperm sparse, fleshy and oily; embryo curved or spirally coiled

Timothy M. A. Utteridge and Laura V. S. Jennings (2022). Trees of New Guinea. Kew Publishing. Royal Botanic Gardens, Kew

Distribution

The New Guinean genera treated here under Cannabaceae were traditionally classified in the tribe Celtidoideae in the Ulmaceae, or placed in their own family Celtidaceae.

Recognition

In New Guinea, these genera have alternate, serrate leaves which are 3-veined from the base or pinnately veined, intrapetiolar stipules, flowers which are unisexual or sometimes appear bisexual, a superior ovary and a drupaceous fruit crowned by a style with 2 divergent branches.

Morphology General Habit

Evergreen or deciduous trees and shrubs, buttresses often present, twigs often zig-zag

Morphology General Indumentum

Indumentum of simple, unicellular hairs with enlarged bases or multicellular, glandular hairs. Stipules present, intrapetiolar or extrapetiolar, usually caducous, free or fused

Morphology Leaves

Leaves simple, alternate, distichous, shortly petiolate, base often asymmetric, margin crenate to serrate, rarely entire, 3-nerved from the base or pinnately veined, veins not entering the marginal teeth

Morphology Reproductive morphology Inflorescences

Inflorescences axillary, pseudo-terminal, or ramiflorous, usually in few-flowered cymes or solitary along the axis, with caducous bracts

Morphology Reproductive morphology Flowers

Flowers unisexual or appearing bisexual, plants monoecious or dioecious, sessile or pedunculate, (4–)5(–7)-merous; perianth in a single whorl, lobes free or fused, imbricate or induplicate in bud; stamens as many as perianth lobes, attached at base of lobes, anthers ovoid to ellipsoid, dehiscing by lateral slits, staminodes in female flowers present or absent; ovary superior, of 2 fused carpels, 1-locular, 1 ovule per locule, placentation apical, style short with 2 divergent stigmatic branches, tips entire to bifid

Morphology Reproductive morphology Fruits

Fruit drupaceous, mesocarp fleshy, endocarp hard.

Cannabinaceae, Hutchinson and Dalziel. Flora of West Tropical Africa 1:2. 1958

Morphology General Habit

Erect or scandent herbs

Morphology Leaves

Leaves alternate or opposite, simple, undivided or more or less palmately lobed; stipules present

Morphology Reproductive morphology Flowers

Flowers dioecious, axillary, male paniculate, female sessile, crowded or strobilate, with large persistent bracts Female flower: calyx closely enveloping the ovary, entire; ovary sessile, 1-celled; style 2-partite Male flower: calyx 5-partite, segments imbricate; petals absent; stamens 5, erect in bud; anthers 2-celled

sex Male

Male flower: calyx 5-partite, segments imbricate; petals absent; stamens 5, erect in bud; anthers 2-celled

sex Female

Female flower: calyx closely enveloping the ovary, entire; ovary sessile, 1-celled; style 2-partite

Morphology Reproductive morphology Flowers Gynoecium

Ovule solitary, pendulous

Morphology Reproductive morphology Fruits

Fruit an achene, covered by the persistent calyx

Morphology Reproductive morphology Seeds

Seed with fleshy endosperm and curved or spiral embryo