Acalypha L.

Euphorbiaceae, A. R.-Smith. Flora of Tropical East Africa. 1987

Morphology General Habit

Monoecious or rarely dioecious annual or perennial herbs, shrubs or rarely trees, of varying habit, but often superficially resembling Urtica species

Morphology General Indumentum

Indumentum usually simple, rarely stellate (some S. American spp.), often glandular

Morphology Leaves

Leaves alternate, usually petiolate, stipulate, elobate, often ovate and toothed, palmi- or penninerved

Morphology Reproductive morphology Inflorescences

Inflorescences various, terminal or axillary or both, uni- or bisexual, spicate, racemose or paniculate, the ♂ inflorescences axillary, slender and catkin-like but erect, the ♀ inflorescences axillary or terminal, most often spicate, rarely racemose or paniculate, the androgynous inflorescences axillary or terminal, spicate or rarely racemose, most often ♀ at the base and ♂ above (either with few ♀’s and many ♂’s or vice versa), less often ♂ at the base and ♀ above

sex Male

Male flowers very small, shortly pedicellate, glomerate in small, inconspicuous bracts Male flowers: calyx closed in bud, later valvately 4-partite; petals and disc 0; stamens usually 8, attached to the slightly raised receptacle, filaments free, broad, anther-thecae distinct, spreading or pendulous, oblong or linear, later becoming flexuous-vermiform; pistillode 0

Morphology Reproductive morphology Flowers

Female flowers: calyx-lobes 3–4(–5), imbricate, small; petals and disc 0; ovary (2–)3-locular, with 1 ovule per locule; styles free or sometimes connate, usually laciniate, reddish and rather showy, rarely entire or bilobed Allomorphic ♀ flowers ebracteate; calyx ± as in the normal ♀ flowers; ovary 1(–2)-locular; styles subbasal Male flowers very small, shortly pedicellate, glomerate in small, inconspicuous bracts Female flowers either sessile and 1–3(–5) within a variously toothed or lobed accrescent bract which becomes foliaceous, or else shortly pedicellate and solitary in the axil of a small, non-accrescent bract; allomorphic ♀ flowers often terminate the inflorescences in some annual species, or may be co-axillary with normal inflorescences in some other species Male flowers: calyx closed in bud, later valvately 4-partite; petals and disc 0; stamens usually 8, attached to the slightly raised receptacle, filaments free, broad, anther-thecae distinct, spreading or pendulous, oblong or linear, later becoming flexuous-vermiform; pistillode 0

sex Female

Female flowers: calyx-lobes 3–4(–5), imbricate, small; petals and disc 0; ovary (2–)3-locular, with 1 ovule per locule; styles free or sometimes connate, usually laciniate, reddish and rather showy, rarely entire or bilobed Allomorphic ♀ flowers ebracteate; calyx ± as in the normal ♀ flowers; ovary 1(–2)-locular; styles subbasal Female flowers either sessile and 1–3(–5) within a variously toothed or lobed accrescent bract which becomes foliaceous, or else shortly pedicellate and solitary in the axil of a small, non-accrescent bract; allomorphic ♀ flowers often terminate the inflorescences in some annual species, or may be co-axillary with normal inflorescences in some other species

Morphology Reproductive morphology Fruits

Fruits of allomorphic ♀ flowers 1(–2)-lobed Fruits 3-lobed, small, soon dehiscing septicidally into 3 bivalved cocci

Morphology Reproductive morphology Seeds

Seeds ellipsoid or subglobose, small, carunculate or not, testa crustaceous, albumen fleshy; cotyledons broad, flat.

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

Distribution

A large genus of 450 species, pantropical especially in Central America and Africa; c. 15 species in New Guinea (at least 7 species are endemic).

Morphology General Habit

Shrubs or small trees to 12 m (A. cinnamomifolia to c. 30 m), or scramblers or herbs Plants monoecious

Morphology General

Latex absent

Morphology General Indumentum

Indumentum of simple hairs simple

Morphology Leaves Stipules

Stipules lanceolate or subulate, sometimes minute

Morphology Leaves

Leaves alternate, simple, narrowly elliptic to obovate, margins crenate to subentire, palmatinerved or penninerved; petiole usually relatively long

Morphology Reproductive morphology Inflorescences

Inflorescences terminal or axillary, spicate or racemose, composed of staminate and pistillate flowers, or with sexes on separate inflorescences, pistillate flowers sometimes solitary, inflorescence bracts often lobed and accrescent in fruit

Morphology Reproductive morphology Flowers

Flowers with petals absent; disk absent Staminate flowers usually minute; calyx splitting into 4 segments; stamens 8, free, anthers bilocular, thecae free, twisted and vermiform at anthesis, filaments lacking glands; disk absent; pistillode absent

Morphology Reproductive morphology Flowers Gynoecium Pistil

Pistillate flowers: sepals 3–5, fused at the base; ovary 3- or 2-locular; styles conspicuous, laciniate

Morphology Reproductive morphology Fruits

Fruit a capsule, 3- or 2-locular, smooth, lacking spines or processes, dehiscing partly loculicidal and completely septicidal, leaving a persistent columella after dehiscing

Morphology Reproductive morphology Seeds

Seeds rounded, smooth, with a conspicuous hilum or caruncle.

Ecology

Found in a variety of habitats including primary and secondary forests, river-banks, roadsides, regrowth, flood plains etc. in lowland to montane areas from 0–2600 m.

Recognition

Acalypha can be recognised by the alternate, simple leaves with dentate margins (subentire in A. subintegra Airy Shaw), the staminate flowers in spicate or racemose inflorescences which lack petals and have 8 stamens with free anther cells which are twisted and elongate, the pistillate flowers with conspicuous and deeply divided and fringed (laciniate) styles; and the usually trilocular smooth capsule lacking any sap (cf. Claoxylon – fruits with purple sap).

M. Thulin et al. Flora of Somalia Vol. 1-4 [updated 2008] https://plants.jstor.org/collection/FLOS

Morphology General Habit

Herbs, shrubs or trees, sometimes mistaken for Urticaceae; indumentum usually simple, often glandular

Morphology Leaves

Leaves alternate, often ovate, toothed

Morphology Reproductive morphology Inflorescences

Mostly monoecious; inflorescences raceme-like, axillary and/or terminal, rarely branched

Morphology Reproductive morphology Flowers

Male flowers minute, in clusters along catkin-like inflorescence. Calyx valvately 4-lobed, closed in bud Female flowers mostly sessile, 1–3(–5) together in axil of accrescent leafy bract, sometimes pedicellate with non-accrescent bract; calyx imbricately 3–5-lobed; petals and disc absent “Allomorphic” (distinctive modified female) flowers sometimes within or terminating male racemes or coaxillary with normal inflorescences

Morphology Reproductive morphology Flowers Corolla

Petals and disc absent

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens usually 8, free, anthers “wormlike” (elongated and contorted)

Morphology Reproductive morphology Flowers Gynoecium

Ovary (2–)3-celled, ovules solitary; styles usually laciniate, often reddish and showy

Morphology Reproductive morphology Fruits

Fruit a small deeply-lobed capsule, soon dehiscent

Morphology Reproductive morphology Seeds

Seeds ellipsoidal or subglobose, smooth, carunculate or not.

Distribution

A large pantropical genus of about 430 species, a few extending into temperate areas of the New World. About 50 species in Africa, mostly in higher rainfall regions

George R. Proctor (2012). Flora of the Cayman Isands (Second Edition). Royal Botanic Gardens, Kew

Morphology General Habit

Herbs, shrubs or rarely trees, monoecious or dioecious, bearing simple hairs or glands; leaves alternate, petiolate, simple, entire or toothed, and with pinnate or palmate venation

Morphology Reproductive morphology Flowers

Flowers in terminal or axillary unisexual or bisexual spikes, the staminate flowers several at each node subtended by a minute bract, the pistillate flowers 1–3 at each node, subtended by a usually large, foliaceous, lobed bract; petals and disc absent Staminate flowers with calyx closed in bud, valvately splitting into 4 lobes at anthesis; stamens 4–8, the filaments free or joined at the base; anther-sacs 1-celled, pendent, elongate and worm-like, opening at the apex; rudimentary ovary absent

Morphology Reproductive morphology Flowers Gynoecium Pistil

Pistillate flowers with 3–5 imbricate calyx-lobes; ovary usually 3-celled with solitary ovules; styles free, thread-like, usually much-branched

Morphology Reproductive morphology Fruits

Fruit a 3-seeded capsule; seeds with or without a caruncle; endosperm present.

Distribution

A large genus of about 400 species, the majority tropical American, with the greatest concentration of species in the Caribbean region.

Note

Acalypha hispida Burm. f., ‘red puss-tail’, from the Indonesian area, and A. amentacea Roxb. subsp. wilkesiana (Muell. Arg.) Fosberg, ‘Joseph’s coat’, from the Pacific islands, are shrubs often cultivated in gardens.

Use

Some introduced ornamentals are grown for their foliage and striking pendent inflorescences.