URTICACEAE

(Nettle family)

• Medicinal / Folk-medicinal aspects: Several species are recorded as being used to prepare poultices for application to boils, carbuncles, wounds, contusions, burns, rashes, itching of the skin, and similar such ailments. •
• Adverse effects: One of the sub-divisions of this family, namely the Urticeae, is characterised by the presence of stinging hairs. The principal stinging nettle genera are Dendrocnide Miq., Laportea Gaudich., Obetia Gaudich., Urera Gaudich., and Urtica L. The usual skin reaction caused by these nettles is categorised as a non-immunologic contact urticaria (Lahti 1980, 1986). Pardo-Castello (1923) noted that the Urticaceae was one the main four families of tropical plants causing dermatitis; Rook (1960), on the other hand, described the stinging nettles in Britain as being of little clinical significance. Additionally, all members of the genus Cecropia Loefl. are reported anecdotally to possess a milky caustic latex. Some species are also covered with a downy tomentum that may produce intense itching when brought into contact with the skin. Most significantly, these plants are "ant plants" and may therefore constitute a dermatological hazard if handled in their natural habitat. •
• Veterinary aspects: Horses are troubled by nettle stings whereas cattle seem more tolerant. Some mammals (goats, gorillas, and rhinoceros, for example) eat nettle leaves, seemingly being unaffected by the stings. •

The family comprises about 1650 species in 55 genera occurring mainly in tropical regions, with a few being found widely distributed in temperate regions. Most are herbs or shrubs; a few are lianes or trees. About 170 species in 6 genera have in the past been considered to belong to a distinct family, namely the Cecropiaceae (Brummitt 1992), but are now once again included in the Urticaceae (Angiosperm Phylogeny Group 2003). The principal genera are Cecropia Loefl. with 61 species, Coussapoa Aubl. with 50 species, Elatostema J.R.Forst. & G.Forst. with 300 species, and Pilea Lindl. with about 650 species (Mabberley 2008). In the past, members of this family have been classified in the Moraceae, a closely-related family.

The family has little horticultural value, the best known probably being the following species, which are grown as house plants or as greenhouse ornamentals (Hunt 1968/70, Mabberley 1997):

Pilea cadierei Gagnepain & Guillaumin — Aluminium Plant

Pilea involucrata Urb. — Friendship Plant

Pilea microphylla Liebm. — Artillery Plant, Pistol Plant, Gunpowder Plant

[syn. Pilea muscosa Lindl.]

Pilea peperomioides Diels — False Peperomia, Chinese Money Plant

Soleirolia soleirolii Dandy — Helxine, Baby's Tears

[syn. Helxine soleirolii Req.] 

Several species yield a useful fibre. For example, Boehmeria nivea Gaudich. provides ramie or rhea fibre used in the manufacture of Chinese grass-cloth, whilst Urtica cannabina L. yields Siberian hemp (Felter & Lloyd 1898, Watt & Breyer-Brandwijk 1962, Perry & Metzger 1980).

Boehmeria caudata Sw.

[Information available but not yet included in database]

Boehmeria cylindrica Sw.

[syns Boehmeria decurrens Small, Boehmeria drummondiana Wedd., Boehmeria cylindrica Sw. var. drummondiana Wedd., Urtica cylindrica L.]

Bog Hemp, Small-Spike False Nettle

[Information available but not yet included in database]

Boehmeria macrophylla Hornem.

[syn. Boehmeria platyphylla Buch.-Ham. ex D.Don]

The presence of cryptopleurine as a minor alkaloid in Boehmeria platyphylla has been reported by Hart et al. (1968). See Boehmeria cylindrica Sw. above.

[Further information available but not yet included in database]

Boehmeria nivea Gaudich.

[syn. Urtica nivea L.]

China Grass, Chinese Silkplant

[Information available but not yet included in database]

Boehmeria virgata Guill.

[syn. Urtica virgata G.Forst.]

[Information available but not yet included in database]

Cecropia Loefl.

Pumpwood, Trumpet Tree, Trumpet Wood, Snake Wood, Yagrumo, Yagrumo Hembra, Llagrumo Hembra, Bois Canot, Guarumo, Guarima, Guarumbo, Trompeta

About 61 species are native to tropical America (Mabberley 2008). Taxonomic revisions in the past have placed the genus in a separate family, namely the Cecropiaceae, and also in the Moraceae.

According to Allen (1943), all species possess a milky, caustic sap, which produces a pronounced rash in some individuals. He also noted that young plants, particularly of an undetermined species found in the mountains north of El Valle de Anton, in Coclé Province (Panama) are densely covered with a downy tomentum, which is readily detached upon contact with the skin, producing intense itching. Willis (1973) stated that this genus does not possess stinging hairs.

Allen (1943) also notes that a further "character which attracts the most immediate attention of the jungle wayfarer is the presence of innumerable restless ants belonging to the genus Azteca, which inhabit, almost without exception, the trunks and hollow branches of the trees. […] The least disturbance of the plants is usually sufficient to awaken herds of the ants, who sally forth in defence of their homes, inflicting painful stings on contact with the skin" [sic; Azteca spp. are biting ants (Janzen 1972)]. In 1874, T. Belt (cited by Wheeler 1942) noted that if the tree be shaken, the ants rush out in myriads and search about for the molester. Dahlgren & Standley (1944) similarly caution that the branches of the trumpet tree (an unspecified Cecropia) are hollow and are inhabited by swarms of small ants that bite painfully as soon as a leaf or branch is touched. Janzen (1969) reported that the ants displayed aggression against humans cutting Cecropia species. Martínez (1969) also refers to these characteristics of Cecropia species. An extensive review of the dermatological hazard associated with such "ant plants" (myrmecophytes) is provided by Schmidt (1985).

The following is a representative list of taxa that have been recognised as being myrmecophytes (Bailey 1922, Wheeler & Bequaert 1929, Longino 1989):

Cecropia angulata I.W.Bailey

Cecropia distachya Huber

[syn. Cecropia riparia Warb. ex Snethl.]

Cecropia ficifolia Warb. ex Snethl.

Cecropia insignis Liebm.

Cecropia latiloba Miq.

[syn. Cecropia paraensis Huber]

Cecropia membranacea Trécul

[syns Cecropia bifurcata Huber, Cecropia laetivirens Huber, Cecropia robusta Huber]

Cecropia montana Warb. ex Snethl.

Cecropia obtusifolia Bertol.

[syn. Cecropia mexicana Hemsl.]

Cecropia pachystachya Trécul

[syns Cecropia adenopus Mart. ex Miq., Cecropia lyratiloba Miq.] 

Others are considered separately below.

Cecropia peltata L.

Trumpet Tree

The hollow stems of this tropical American tree are often inhabited by fierce ants (Azteca sp.) which rush out if the tree is shaken and attack the intruder (Menninger 1967). Mabberley (2008) noted that Cecropia peltata in Puerto Rico has 98% of its trees without this symbiotic trait whereas in Trinidad and on the tropical American mainland all trees have it.

Dendrocnide Miq.

This is a genus of about 37 species of stinging trees found in Indomalaysia and the Pacific region (Chew 1969a, Mabberley 1997, Chen et al. 2003d). Several are known to sting violently producing urticaria and shock (Everist 1972). The following is a representative list:

Dendrocnide basirotunda Chew — found in China, Thailand

[syn. Laportea basirotunda C.Y. Wu]

Dendrocnide corallodesme Chew — Mango-Leaved Stinger — found in Australia

[syn. Laportea corallodesme Lauterb.]

Dendrocnide cordifolia Jackes & M. Hurley — found in Australia

[syn. Laportea cordifolia L.S. Sm.]

Dendrocnide harveyi Chew — Salato, Magiho — found in Fiji, Tonga, Samoa, Cook Islands

[syn. Laportea harveyi Seem.]

Dendrocnide photinophylla Chew — Gympie Stinger, Mulberry-Leaved Stinger — found in Australia

[syns Fleurya photinophylla Kunth, Laportea photinophylla Wedd.]

Dendrocnide sinuata Chew — Devil Nettle, Fever Nettle — found in China, India, Malaysia, Sri Lanka, Thailand

[syns Laportea crenulata Gaudich., Urtica crenulata Roxb., Urtica sinuata Blume]

Dendrocnide ternatensis Chew — found in Papua New Guinea

[syn. Laportea ternatensis Miq.]

Dendrocnide urentissima Chew — found in China, Vietnam

[syn. Laportea urentissima Gagnep.] 

Two French tourists, one returning from Vietnam, the other from the island of Mindoro in the Philippines sought medical attention after coming into contact with unidentified stinging trees, which were thought to have been Dendrocnide urentissima Chew in Vietnam and either Dendrocnide meyeniana Chew or Dendrocnide stimulans Chew on Mindoro. The skin reaction in the patient returning from Vietnam resolved in few days whilst the pruritic and painful reaction in the case from Mindoro lasted for over 3 weeks (Schmitt et al. 2013).

[Further information available but not yet included in database]

Dendrocnide cordata Chew

[syn. Laportea cordata Warb.]

Stinger, Cordate Stinging Bush

Several publications (Robertson & Macfarlane 1957, Macfarlane 1963a, Leung et al. 1986, Oelrichs & Robertson 1970) cite Winkler (1922) as the source of a report of a human fatality caused by the stinging hairs of Laportea condata [sic] in New Guinea. Robertson & Macfarlane (1957) went further to add that Laportea condata is not found in Australia. In fact, Winkler (1922) was referring to the toxicity of the dried bark of Laportea cordata when mixed into food: "die getrocknete Rinde soll, ins Essen gerührt, tödlich wirken". Furthermore, this species is found in northern tropical Australia as well as in Timor, the Tanimbar Islands, and in New Guinea and the Bismarck Archipelago, it resembling Dendrocnide moroides but being altogether less irritant (Chew 1969a).

Dendrocnide excelsa Chew

[syns Laportea gigas Wedd., Urera excelsa Wedd., Urera rotundifolia Wedd.]

Giant Stinger, Giant Stinging Tree

This species is found in the rain forests of northern Queensland. Bushmen avoid these trees as they would the plague, for the young leaves particularly, and also the branchlets, are covered with stinging silicone [sic] hairs that inject formic acid [sic] into the skin of anyone who touches them (Menninger 1967). Petrie (1906) carried out a detailed study of this nettle. He noted that its leaves are covered with numerous strong hairs or bristles which are filled with a powerful stinging fluid. If the leaves be lightly touched with the hand, the bristles penetrate and break in the skin, causing pain which, however slight at first, gradually increases in severity and sometimes lasts for many days. The pain keeps returning whenever the injured part is wet. Petrie (1906) demonstrated the presence of formic acid in the plant and in the stinging fluid (which turned blue litmus red). However, formic acid does not account fully for the effect of the stings of this tree. The stinging hairs appear to be silicaceous because they retain their structure when heated to redness. Cleland (1914), Wimmer (1926), and Cleland & Lee (1963) also refer to the urticating properties of this stinging tree.

[Further information available but not yet included in database]

Dendrocnide kotoensis B.L.Shih & Yuen P.Yang

[syn. Laportea kotoensis Hayata ex Yamamoto]

[Information available but not yet included in database]

Dendrocnide latifolia Chew

[syn. Laportea latifolia Gaudich.]

[Information available but not yet included in database]

Dendrocnide luzonensis Chew

[syns Laportea crenulata Gaudich. var. luzonensis Wedd., Laportea luzonensis Warb.]

Bungabung

This species is found in the Philippines. Fairchild (1943) described his experience after touching one of the glandular poison hairs of Laportea luzonensis with his fore-finger. He experienced intense pain that lasted for days and produced a feeling of paralysis in the tip.

[Further information available but not yet included in database]

Dendrocnide meyeniana Chew

[syns Laportea gaudichaudiana Wedd., Laportea pterostigma Wedd., Urtica meyeniana Walpers, Urticastrum pterostigma Kuntze]

Man-Biting Dog

This tree, which is armed with stinging hairs, is found in Taiwan and the Philippines (Chew 1969a, Shih et al. 1995, Chen et al. 2003d). Uchida & Norikane (1936) were most probably referring to this species when they reported the results of their investigation of the dermatitis produced by a Formosan [= Taiwanese] nettle they identified as Laportea pterostidua Wedd [sic]. They considered the skin reaction (comprising inflammation, infiltration, swelling, itching, and pain) to be peculiarly painful like pricking with needles. In addition, they believed that they had demonstrated the presence of formic acid in the sting toxin.

Dendrocnide morobensis Chew

Conn & Damas (2005f), in their online Guide to Trees of Papua New Guinea, note that stinging hairs are present on this nettle but are very sparse on the leaves, inflorescences and flowers.

Dendrocnide moroides Chew

[syns Laportea moroides Wedd., Urticastrum moroides Kuntze]

Gympie Stinger, Mulberry-Leaved Stinger

[Information available but not yet included in database]

Dendrocnide peltata Miq. var. murrayana Chew

[syn. Laportea murrayana Rendle ex Baker f.]

Jelaton, Stinging Tree

This taxon, which is found on Christmas Island, has fewer stinging hairs than var. peltata and consequently inflicts a less severe sting (Du Puy & Telford 1993).

Dendrocnide peltata Miq. var. peltata

[syn. Urtica peltata Blume]

Jelaton, Stinging Tree

Du Puy & Telford (1993) noted that all parts of the plant sting severely. According to Conn & Damas (2005d) in their online Guide to Trees of Papua New Guinea, the presence of stinging hairs on this plant makes the leaves and branchlets moderately painful to touch.

Dendrocnide schlechteri Chew

[syn. Laportea schlechteri Winkl.]

[Information available but not yet included in database]

Dendrocnide stimulans Chew

[syns Laportea annamica Gagnep., Laportea stimulans Miq., Urtica stimulans L.f., Urticastrum stimulans Kuntze]

Malay Nettle Tree, Elephant Nettle Tree

[Information available but not yet included in database]

Dendrocnide subclausa Chew

[syn. Laportea subclausa C.B.Rob.]

This Australian species stings so badly that the effects may be felt for months. Horses suffer severely from it but cattle do not (Fairchild 1943).

[Further information available but not yet included in database]

Discocnide mexicana (Liebm.) Chew

[syns Discocarpus mexicanus Liebm., Laportea nicaraguensis Wedd., Laportea mexicana Wedd., Urticastrum nicaraguense Kuntze]

Ortiga

[Information available but not yet included in database]

Elatostema banahaense C.B.Rob.

[Information available but not yet included in database]

Girardinia Gaudich.

The genus currently comprises just 2 species with several subspecies (Mabberley 1997, Chen et al. 2003e). Girardinia bullosa Wedd. (syn. Urtica bullosa Hochst. ex Steud.) is found in East and North East Africa; Girardinia diversifolia Friis is more widely distributed in warm and tropical regions of Asia.

Girardinia diversifolia Friis subsp. diversifolia

[syns Girardinia chingiana S.S.Chien, Girardinia condensata Wedd., Girardinia heterophylla Decne., Girardinia leschenaultiana Decne., Girardinia palmata Gaudich., Girardinia zeylanica Decne., Urtica diversifolia Link, Urtica heterophylla Vahl, Urtica horrida Link]

Himalayan Nettle, Nilgiri Nettle

Girardinia zeylanica yields a fibre that has been used for making clothes, with unpleasant results, owing to the extreme difficulty experienced in entirely removing the stinging principles, even in the severe processes to which the plant is subjected in order to extract the fibre (Philip Smith 1920a).

Extracts prepared from the whole leaves of Girardinia heterophylla homogenised in acetone have been shown to contain histamine, 5-hydroxytryptamine, and acetylcholine (Saxena et al. 1964, Saxena et al. 1966), it being suggested that these substances are responsible in whole or in part for the pain, triple response and dermatitis caused by the stings of this nettle [see also Dendrocnide moroides Chew above].

[Further information available but not yet included in database]

Gonostegia hirta Miq.

[syns Memorialis hirta Wedd., Pouzolzia hirta Blume ex Hassk.]

[Information available but not yet included in database]

Gyrotaenia Griseb.

This little-studied genus comprises six species found in the West Indies (Mabberley 1997). Thurston & Lersten (1969) noted that stinging hairs are known from this genus, but provided no further detail.

Hesperocnide Torr.

The two species, one native to Hawai‘i the other to California, possess stinging hairs (Thurston & Lersten 1969, Hardin & Arena 1974):

Hesperocnide sandwicensis (Wedd.) Wedd. — Hawaii Stinging Nettle

[syn. Urtica sandwicensis Wedd.]

Hesperocnide tenella Torr. — Western Stinging Nettle 

Laportea Gaudich.

Mabberley (1997) noted that 21 species are found in tropical and warm temperate regions of eastern Asia and north-eastern America; Chen et al. (2003c) asserted that there are about 28 species. All are armed with stinging hairs (Chew 1965, Chen et al. 2003c) with the exception of Laportea ruderalis Chew (Chew 1969b). Plants previously classified in the genera Fleurya Gaudich. and Sceptrocnide Maxim. have been moved into this genus, some being moved on with other Laportea species into Dendrocnide Miq. [see above].

Interestingly, Levin (1973) citing Schaller (1963) noted that mountain gorillas are apparently insensitive to the stinging hairs of Laportea, feeding on the leaves and stems without hesitation. The unnamed Laportea species to which these authors alluded may well have been species now classified in the genus Dendrocnide Miq. [see above].

The following is a representative list. Others are considered in more detail in the monographs below:

Laportea bulbifera Wedd. — found in south east Asia

[syns Fleurya bulbifera Blume ex Miq., Laportea sinensis C.H.Wright, Laportea terminalis Wight, Urtica bulbifera Siebold & Zucc.]

Laportea canadensis Wedd. — Canadian Wood Nettle, Grande Ortie — found in eastern North America, Mexico

[syns Urtica canadensis L., Urticastrum divaricatum Kuntze]

Laportea cuneata Chew — found in Central America (Pardo-Castello 1923, Wimmer 1926, Weber 1930, Chew 1969b, von Reis & Lipp 1982)

[syns Fleurya cuneata Wedd., Fleurya umbellata Wedd., Urtica cuneata A.Rich.]

Laportea fujianensis C.J.Chen — found in China

Laportea medogensis C.J.Chen — found in China

Laportea violacea Gagnep. — found in China, Thailand, Vietnam 

Laportea aestuans Chew

[syns Fleurya aestuans Gaudich. ex Miq., Fleurya glandulosa Wedd., Fleurya perrieri Leandri, Laportea bathiei Leandri, Urtica aestuans L.]

Ortiga, Pica-Pica, West Indian Nettle, Scratch Bush, Cow Itch

This nettle is found in Central America and the West Indies, tropical Africa, and from India through SE Asia to Java and the Lesser Sunda Islands (Du Puy & Telford 1993). Allen (1943) notes that the plants are annoying weeds in neglected banana plantations. The fleshy stems are covered with weak hairs which produce an active burning sensation on contact with the skin. While these plants are comparatively mild as compared with some more violent Central American "ortigas", nevertheless the spines will penetrate wet trousers, causing considerable burning and discomfort, which may last for several hours.

[Further information available but not yet included in database]

Laportea cuspidata Friis

[syns Girardinia cuspidata Wedd., Laportea forrestii Diels, Laportea macrostachya Ohwi, Sceptrocnide macrostachya Maxim.]

[Information available but not yet included in database]

Laportea decumana Wedd.

[syn. Urtica decumana Roxb.]

[Information available but not yet included in database]

Laportea interrupta Chew

[syns Fleurya interrupta Gaudich., Urtica interrupta L.]

Hawaii Woodnettle, Fowl Nettle

[Information available but not yet included in database]

Laportea peduncularis Chew subsp. peduncularis

[syns Fleurya capensis Wedd., Fleurya mitis Wedd., Urtica capensis E.Mey. ex Wedd., Urtica mitis E.Mey.]

Referring to Fleurya mitis, Watt & Breyer-Brandwijk (1962) noted that this South-African plant produces stinging effects similar to those of Urtica.

Laportea peltata Gaudich.

[Information available but not yet included in database]

Leucosyke capitellata Wedd.

[syn. Urtica capitellata Poir.]

[Information available but not yet included in database]

Myriocarpa stipitata Benth.

[syns Myriocarpa densiflora Benth., Myriocarpa dombeyana Wedd.]

Ishanga

[Information available but not yet included in database]

Nanocnide Blume

Two species are found in temperate regions of eastern Asia (Mabberley 1997). Both are recognised as being stinging nettles (Thurston & Lersten 1969, Chen et al. 2003b):

Nanocnide japonica Blume

[syn. Nanocnide dichotoma S.S.Chien]

Nanocnide lobata Wedd.

[syn. Nanocnide pilosa Migo] 

Obetia Gaudich.

According to Mabberley (1997), the genus comprises eight species of stinging trees found in tropical Africa, Madagascar and the Mascarenes. Thurston & Lersten (1969) noted that stinging hairs are known in members of this genus but provided no further information. Friis (1983) listed six species, noting that stinging hairs are found on all members of the genus.

In addition to the species considered in more detail below, the following may be listed:

Obetia aldabrensis Friis

[syn. Urtica ficifolia Poir.]

Obetia madagascariensis Wedd.

[syns Urera madagascariensis Gaudich., Urtica madagascariensis Juss. ex Poir.] 

Obetia carruthersiana Rendle

[syns Laportea carruthersiana K.Schum., Obetia australis Engl., Urticastrum carruthersianum Hiern]

Angola Nettle, Namib Nettle

According to the South African National Biodiversity Institute (SANBI 2019), the Namib stinging nettle has large spiny leaves bearing irritant sap.

Obetia ficifolia Gaudich.

This species may be found in succulent plant collections. Burston et al. (1997) could detect no stinging hairs on young specimens, these reportedly (Friis 1983) being restricted to the inflorescences of mature plants.

Obetia radula Baker ex B.D. Jackson

[syns Obetia laciniata Baker, Obetia morifolia Baker, Obetia pinnatifida Baker, Urera radula Baker]

In a study of the sting toxin from Obetia pinnatifida, Maitai et al. (1981) found histamine, acetylcholine and serotonin to which they attributed the stinging sensation caused by these nettles [see also Dendrocnide moroides Chew above]. They also found three other substances that they failed to characterise.

[Further information available but not yet included in database]

Obetia tenax Friis

[syn. Urera tenax N.E.Br.]

Mountain Nettle, Tree Nettle, Rock Tree Nettle, Mucucula

The leaves and young twigs of Urera tenax are well supplied with ferocious stinging hairs (Watt & Breyer-Brandwijk 1962). According to Mullin (2005) of the Tree Society of Zimbabwe, black rhino have been known to munch pensively on the leaves of this tree — which has the endearing quality of raising blisters on any human hand that happens to brush against its stinging hairs.

Oreocnide frutescens Miq. subsp. frutescens

[syns Boehmeria frutescens Thunb., Urtica frutescens Thunb., Villebrunea frutescens Blume]

[Information available but not yet included in database]

Oreocnide integrifolia Miq.

[syn. Villebrunea integrifolia Gaudich.]

[Information available but not yet included in database]

Oreocnide rubescens Miq.

[syns Villebrunea rubescens Blume, Urtica rubescens Blume]

[Information available but not yet included in database]

Parietaria judaica L.

[syn. Parietaria diffusa Mert. & Koch]

Pellitory-of-the-Wall

[Information available but not yet included in database]

Pellionia repens Merr.

[syns Elatostema repens Hallier f., Polychroa repens Lour.]

[Information available but not yet included in database]

Pilea Lindl.

[Information available but not yet included in database]

Pilea microphylla Liebm.

[syns Parietaria microphylla L., Urtica microphylla Sw.]

Artillery Plant, Artillery Weed, Pistol Plant, Gunpowder Plant, Rockweed

[Information available but not yet included in database]

Pilea pumila A.Gray

[syn. Urtica pumila L.]

Clearweed, Coolweed, Richweed, Stingless Nettle

[Information available but not yet included in database]

Pilea umbrosa Blume

[Information available but not yet included in database]

Pipturus arborescens C.B.Rob.

[syn. Urtica arborescens Link]

[Information available but not yet included in database]

Pipturus argenteus Wedd.

[syns Boehmeria irritans Ridl., Pipturus argenteus Wedd. var. lanosus Skottsb., Urtica argentea G.Forst.]

False Stinger, White Mulberry, White Nettle, Pulus Scrobbo

In the traditional medicine of New Guinea, the juice is applied to fresh wounds or an aching tooth (Perry & Metzger 1980).

Ridley (1926) applied the name Boehmeria irritans to a shrub / small tree he catalogued as Ridley 156a, which he had collected in Flying Fish Cove on Christmas Island, noting that it "stings as badly as Laportea". More recent works identify Boehmeria irritans as a synonym of Pipturus argenteus Wedd. var. lanosus Skottsb. (Du Puy & Telford 1993), or of Pipturus argenteus Wedd. (Wilmot-Dear & Friis 2013). Confusingly, these and other publications (Merlin et al. 1997, Conn & Damas 2005e) note that members of the genus Pipturus Wedd. do not bear stinging hairs. A possible explanation is that Ridley experienced the sting of Laportea murrayana Rendle, a species he also collected in Flying Fish Cove (which he catalogued as Ridley 157; see Du Puy & Telford 1993), erroneously believing that he had been stung by the plant to which he accordingly applied the name Boehmeria irritans.

Pipturus velutinus Wedd.

[syn. Pipturus incanus Wedd.]

[Information available but not yet included in database]

Pouzolzia sanguinea Merr. var. elegans Friis & Wilmot-Dear

[syns Boehmeria elegantula Hand.-Mazz., Pouzolzia elegans Wedd., Pouzolzia elegantula W.W.Sm. & Jeffrey]

[Information available but not yet included in database]

Pouzolzia sanguinea Merr. var. sanguinea

[syns Boehmeria nepalensis Wedd., Pouzolzia viminea Wedd., Urtica sanguinea Blume]

[Information available but not yet included in database]

Pouzolzia zeylanica Bennett & R.Br.

[syns Parietaria indica L., Parietaria zeylanica L., Pouzolzia indica Wight]

[Information available but not yet included in database]

Urera Gaudich.

Mabberley (1997) notes that the genus comprises 35 species of trees and shrubs bearing powerful stinging hairs. They are found in Hawai‘i, warm America, tropical and southern Africa, and Madagascar. Some make useful hedge plants.

The following is a representative list of better-known species. Others are considered in the monographs below:

Urera chlorocarpa Urb. — Ortiga, Stinging Nettle — found in the Caribbean region

Urera domingensis Urb. — found in Central America (Pardo-Castello 1923, Wimmer 1926)

Urera hypselodendron (Hochst. ex A.Rich.) Wedd. — found in East Africa (Friis 1985)

[syns Urera schimperi Wedd., Urtica hypselodendron Hochst. ex A.Rich.]

Urera laciniata Goudot ex Wedd. — found in Central America

[syn. Urtica laciniata Goudot ex Wedd.]

Urera oblongifolia Benth. — found in East Africa

Urera obovata Benth. — found in East Africa

Urera repens Rendle — found in East Africa

[syn. Laportea repens Wedd.]

Urera rigida Keay — found in East Africa

[syns Boehmeria rigida Benth., Urtica rigida G.Don ex Benth.]

Urera robusta A.Chev. — found in East Africa

Urera sansibarica Engl. — found in eastern Africa (Friis 1985)

Urera trinervis Friis & Immelman — Climbing Nettle — found in eastern, central, & southern Africa (Friis 1985)

[syns Elatostema trinerve Hochst., Urera acuminata Gaudich. ex Decne var. cameroonensis Leandri, Urera cameroonensis Wedd., Urera woodii N.E.Br.] 

[Further information available but not yet included in database]

Urera baccifera Gaudich.

[syn. Urtica baccifera L.]

Ortiga, Jamo, Chichicate, Chichicaste, Chichicastre, Pringamoza, Nettle Tree, Scratch Bush, Cow-Itch

According to Allen (1943), two varieties are recognised, namely var. angustifolia Wedd. and var. horrida Wedd.

All parts of the plant are covered with stout, white, spine-like hairs that cause excruciating pain and inflammation on contact with the flesh. This is without doubt the most severe of the several nettles native to Panama, and the jungle traveller should be constantly alert to avoid contact with the plants. The pain and inflammation may last from a few hours to several days, swelling, fever, and ulcers being produced in extreme cases (Allen 1943). According to Standley (1937), this is one of the most dangerous plants of Central America. Dahlgren & Standley (1944) similarly caution that if the leaves or branches strike the body, intense pain is produced with irritation that may last 24 hours or more. They note also that there is no permanent injury nor is there need for treatment. Pardo-Castello (1923), Wimmer (1926), Weber (1930), and Thurston & Lersten (1969) also referred to this nettle.

Allen (1943) further notes that the plants are used in some parts of Central America for living fences, forming a most effective barrier.

Urera caracasana Gaudich. ex Griseb.

[syns Urera jacquini Wedd., Urtica caracasana Jacq.]

Flameberry, Scratch Bush, Chichicaste, Mala Mujer, Mal Hombre, Quemador

Allen (1943) notes that this species, which may form a shrub or a scandent shrubby vine from nine to twenty-five or more feet tall, is common throughout most of Central America. The plants are covered with slender stinging hairs, which produce burning and inflammation on contact with the skin. However, Dao (1967) noted that the stings are of little concern, being much less troublesome than those of Jatropha urens L. (fam. Euphorbiaceae). von Reis & Lipp (1982) also referred to the ability of the plant to irritate the skin.

Urera mannii Benth. & Hook.f. ex Rendle

[syn. Scepocarpus mannii Wedd.]

[Information available but not yet included in database]

Urtica L.

The genus comprises about 80 species found mostly in northern temperate regions, with a few in tropical and south temperate regions (Mabberley 1997). The American and European species produce less severe stinging than those growing in the East Indies. Harrison (1906) included "Urticæ" in a list of plants that may cause dermatitis; historical literature referring to the stinging hairs of Urtica species was discussed by Uphof (1962) and by Thurston & Lersten (1969).

The following species have been reported to cause stinging:

Urtica cannabina L. — Siberian Hemp Nettle, Kentucky Hemp, Sibirische Hanfnessel — found in Europe, C and SW Asia, Mongolia, China, Siberia

Urtica chamaedryoides Pursh — Heartleaf Nettle, Weak Nettle, Ortiguilla — found in the United States and northern Mexico

[syns Urtica alba Raf., Urtica purpurascens Nutt.]

Urtica dioica L. subsp. gracilis Selander — American Stinging Nettle, California Nettle, Slender Nettle, Western Nettle, Indian Spinach; Ortie Dioique d'Amérique — found in the United States and Canada

[syns Urtica californica Green, Urtica dioica var. lyallii C.L.Hitchc., Urtica gracilis Aiton, Urtica lyallii S.Watson, Urtica viridis Rydb.]

Urtica dioica L. subsp. holosericea Thorne — found in the United States and Mexico

[syns Urtica breweri S.Watson, Urtica holosericea Nutt.]

Urtica echinata Benth. — found in Argentina

[syn. Urtica andicola Wedd.]

Urtica hyperborea Jacq. ex Wedd. — found in India

Urtica gracilenta Greene — Mountain Nettle — found in North America

Urtica incisa Poir. — found in Australia

Urtica leptophylla Kunth — found in Central America

[syn. Urtica nicaraguensis Liebm.]

Urtica magellanica Juss. ex Poir. — Ortiga — found in South America

Urtica membranacea Poir. ex Savigny

Urtica pilulifera L. — Roman Nettle, Pillen-Brennnessel — found in Southern Europe, India, South Africa

Urtica urentissima Comm. ex Pers. — Devil's Leaf — found in India 

Urtica dioica L.

Common Nettle, Stinging Nettle, Große Brennnessel, Ortie Brulante, Ortie Piquante

This nettle is widely distributed through the United States, Eurasia, Australia, South Africa, and India. Gerarde (1636) referred to this nettle as Urtica urens, and to the small nettle (i.e. Urtica urens L. [see below]) as Urtica minor. The species is rather variable, numerous varieties and subspecies having been described.

A well-known [but unproven] popular remedy for relieving the discomfort caused by nettle stings is to rub the area with the crushed leaf of a dock plant Rumex spp. (fam. Polygonaceae), which conveniently is often to be found growing nearby (Thiselton-Dyer 1889, Behl & Captain 1979). However, the work of Robertson & Macfarlane (1957) on supposed antidotes for the stings of Laportea moroides Wedd. would suggest that any relief obtained might be derived from the rubbing action rather than from any specific chemical antidote present in dock leaves.

[Further information available but not yet included in database]

Urtica ferox G.Forst.

Tree Nettle, Ongaonga

In traditional Māori (New Zealand) medicine, the bark is boiled with Macropiper leaves [? Macropiper excelsum Miq., fam. Piperaceae] and taken internally and externally for eczema and venereal disease (Brooker & Cooper 1961b).

[Further information available but not yet included in database]

Urtica parviflora Roxb.

[Information available but not yet included in database]

Urtica thunbergiana Siebold & Zucc.

[syn. Urtica macrorrhiza Hand.-Mazz.]

[Information available but not yet included in database]

Urtica urens L.

Dwarf Nettle, Burning Nettle, Dog Nettle, Annual Nettle, Small Nettle, Kleine Brennnessel

[Information available but not yet included in database]

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