CRYPTERONIACEAE

• Medicinal / Folk-medicinal aspects: •
• Adverse effects: The wood of Dactylocladus stenostachys Oliv. is said to produce irritant effects in woodworkers. One or two species of Crypteronia Blume may elicit a pseudophytodermatitis in those who encounter these trees in their natural habitat. •
• Veterinary aspects: •

This is a small tropical Asian family^a of 12 species of trees and shrubs in three genera, namely Axinandra Thwaites [4 spp.], Crypteronia Blume [7 spp.], and Dactylocladus Oliv. [1 sp.].

^a https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:77126654-1; accessed February 2023

Crypteronia griffithii C.B.Clarke

In Peninsular Malaysia, this tree is seemingly obligatorily inhabited by ants of the genus Cladomyrma Wheeler, 1920. Moog et al. (1998) observed that whilst the ants are obligatorily associated with the tree and do act as biotic defence agents protecting the leaves from phytophagous insects, the ant-plant association appears to be restricted to juvenile trees up to 8 m tall, the mature flowering tree no longer being inhabited by the Cladomyrma ants. Young Crypteronia griffithii saplings are occupied primarily by Cladomyrma maschwitzi Agosti, Moog & Maschwitz, 1999, due to the smaller twig diameter, giving the smaller Cladomyrma maschwitzi queens priority of access to the host plant resource. However, a large percentage of older saplings subsequently become colonised by Cladomyrma crypteroniae Agosti, Moog & Maschwitz, 1999 (Agosti, Moog & Maschwitz, 1999). Although sphecid wasp-like in their behaviour, Maschwitz et al. (1991) noted that, unlike the Cladomyrma species they found in nearby Saraca thaipingensis Cantley ex Prain (fam. Leguminosae), they were not aggressive. Nevertheless, this plant growing in its natural habitat may be categorised as a "super-nettle" capable of eliciting a pseudophytodermatitis (see Schmidt 1985): Agosti, Moog & Maschwitz (1999) noted that as a rule, mature colonies of Cladomyrma will display aggressive behavior if the nest (i.e. plant) is violently disturbed. However, there seems to exist a species-dependent variation in the degree of aggression. Cladomyrma maschwitzi appears to be less aggressive when disturbed than are other species. In some species the major workers will search for and bite into tender spots of any myrmecologist [or plant collector] even two hours after he has broken up [or disturbed] the nest. Cladomyrma workers (andrei, maschwitzi, and petalae) are not only able to bite but to spit as well.

Dactylocladus stenostachys Oliv.

Jongkong, Medang Tabak

The genus Dactylocladus Oliv. is monotypic and was formerly considered a member of the Melastomataceae.^a This is a tree that is found in fresh-water peat swamps in Borneo.

The wood of this tree is said to produce irritant effects in woodworkers (Orsler 1973).

According to Woods & Calnan (1976) the colloquial name "tabak", which is used in Sarawak for the wood, suggests that it is known there as a nasal irritant because the sawdust irritates the nose like snuff. They refer to the toxic wood, ipê tabaco (Tabebuia ipe (Mart. ex K.Schum.) Standl. [now considered to be a synonym of Handroanthus heptaphyllus (Vell.) Mattos], fam. Bignoniaceae) by analogy. Ogata et al. (2008) note that the bark is rich in fibres that are 1-1.5 mm long and have pointed tips, adding that these fibres are irritant to the skin in processing the timber. It may be supposed that these fibres would also be irritating to the nose if inhaled.

^a https://plants.jstor.org/specimen/bm000944546; accessed February 2023

References

• Agosti D, Moog J, Maschwitz U (1999) Revision of the oriental plant-ant genus Cladomyrma. American Museum Novitates (3283): 1-24 [doi] [url]
• Maschwitz U, Fiala B, Moog J, Saw LG (1991) Two new myrmecophytic associations from the Malay Peninsula: ants of the genus Cladomyrma (Formicidae, Camponotinae) as partners of Saraca thaipingensis (Caesalpiniaceae) and Crypteronia griffithii (Crypteroniaceae). 1. Colony foundation and acquisition of trophobionts. Insectes Sociaux 38(1): 27-35 [doi] [url] [url-2]
• Moog J, Drude T, Maschwitz U (1998) Protective function of the plant-ant Cladomyrma maschwitzi to its host, Crypteronia griffithii, and the dissolution of the mutualism (Hymenoptera: Formicidae). Sociobiology 31(1): 105-129 [url] [url-2]
• Ogata K, Fujii T, Abe H, Baas P (2008) Identification of the Timbers of Southeast Asia and the Western Pacific. Hiyoshidai, Japan: Kaiseisha Press [WorldCat] [url]
• Orsler RJ (1973) Personal communication to JC Mitchell from the Forest Products Research Laboratory, Princes Risborough, England. In: Mitchell J, Rook A (1979). Botanical Dermatology. Plants and plant products injurious to the skin. Vancouver: Greengrass, p. 236 [WorldCat] [url]
• Schmidt RJ (1985) The super-nettles: a dermatologist's guide to ants in the plants. International Journal of Dermatology 24(4): 204-210 [doi] [url] [url-2] [pmid]
• Woods B, Calnan CD (1976) Toxic woods. British Journal of Dermatology 95(Suppl 13): 1-97 [doi] [url] [url-2] [pmid]

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