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Description and Distribution: “Dendrocnide was established by Miquel in 1851 to accommodate, as the epithet implies, the tree Nettles” (Chew 1969:1). Here we focus on the putative Micronesian species Dendrocnide latifolia (Gaud.) Chew and/or Dendrocnide kusaiana (Kanehira) Chew. Referring to the Dendrocnide plants in the tropical Pacific region, Chew (1969:74) made the following relevant comments:
“Being so widely spread over the Pacific, it is natural that it should have a fairly wide range of variation not only in leaf form and size but also in the vestiture of the petioles and stipules. The lamina vary from the very small, narrowly elliptic ones with absolutely glabrous petioles in Solomon Islands to the large ovate or even obovate one with dense pubescent petioles found in the Marianna Islands. That Kanehira [Japanese botanist in the 1930s] should have two species described from this great variation is therefore not surprising” [these species reported from Micronesia are Dendrocnide latifolia and Dendrocnide kusiana]
Dendrocnide is a genus of 37 species of shrubs to large trees in the nettle family Urticaceae; these woody plants have a wide distribution across Southeast Asia, Australia and into the tropical Pacific region. Stone (1970:253) succinctly referred to special features of Dendrocnide in his “Key to Local Genera” on Guam: “Leaves glossy green on both surfaces; inflorescence with stinging hairs.” Stone (1970:253) also noted the leaves of Dendrocnide species are “alternate, simple, entire or serrate, tri- or penni-nerved.” Dendrocnide latifolia and Dendrocnide kusiana are, as one or both species, reportedly found on some high islands in Micronesia (note: Dendrocnide harveyi has also been reported, probably incorrectly, as part of the Micronesian flora, e.g., see http://www.fao.org/docrep/013/al568E/al568E.pdf). In any case, it is important to recognize these woody plant species in the genus Dendrocnide because they can be poisonous and may be harmful to people. They may also be noxious to other plants around them. On the other hand, Costion (2011:163) offered the following relevant comments regarding the “stinging nettle family” and its presence in Micronesia:
“The Urticaceae is the stinging nettle family. To “urticate” means to produce a stinging or itching sensation. Many members of this family have glandular hairs that contain mild to severe neurotoxins in them. The sting can vary from a mild itch, as in many temperate herbaceous Urtica species, to severe pain requiring medical attention as in some arborous
Dendrocnide species. Dendrocnide latifolia is native to Micronesia can produce a mild but harmless sting. The flowers of this family [Urticaceae] are small and mostly wind pollinated and thus distinctively non-showy” (also see Costion and Lorence 2012:89).
If, in fact, the “sting” of native Dendrocnide species in Micronesia are normally “mild” and “harmless” than this could be explained by the relative geographical isolation of these Remote Oceanic islands and the resultant lack of native mammals or other animals that might threaten the existence of these plants through excessive herbivory.
Note: Here taxonomically, Dendrocnide latifolia is considered to be one of following: (1) a synonym for D. kusiana; (2) a separate species independent of D. kusiana, or (3) the accepted single Micronesian species with D. kusiana as a synonym of D. latifolia.
Presence of Dendrocnide in Micronesia: The Japanese botanists Hosokawa and Kanehira collected specimens of Dendrocnide on Saipan, Rota, Pohnpei, and Kosrae in the 1930s (e.g., see Chew 1969). Fosberg (1946) reported “Dendrocnide latifolia (Gaud.) Chew” from Chuuk with local names of kahtat, kahtl, katud (see also Falanruw et al. 1990; the specimen collected by Fosberg may be Fleurya or Laportea interrupta?). Stone (1970:255) indicated that there is one species in Guam, “Dendrocnide latifolia (Gaud.) W.L. Chew,” but for “some reason, it is not mentioned by Safford or Merrill,” the key botanists who had previously studied the flora of the Mariana Islands. Stone (1970:255) referred to Dendrocnide latifolia as a small, dioecious tree and “unlike most in the genus, is harmless and nearly devoid of stinging hairs; only the inflorescences should not be handled.” Stone noted the uncommon occurrence of Dendrocnide latifolia in limestone areas, woodland, and on cliffs in the “Marianas, Carolines, Solomon Is., New Hebrides, Loyalty Is., New Caledonia” (also see Chew 1969 for his monograph on Dendrocnide; as well as Muniappan 1976 for more on the presence of D. latifolia on Guam). D. latifolia was reported in Micronesia by Craig (1992) in the remnant native limestone forest in the Marpi region of Saipan, in the Mariana Islands. On the other hand, others have recognized or referred to Dendrocnide kusiana (Kanehira) Chew as restricted in its range to the eastern Caroline Islands of Pohnpei and Kosrae; if this species identification is valid than D. kusiana is endemic to these two high volcanic islands (e.g., see Falanruw 2002:18).
Dendrocnide on Pohnpei: The online Pohnpeian-English dictionary lists D. latifolia as known in Pohnpeian as “leles” which has leaves that “cause itching” [http://www.trussel2.com/PNP/pnp-l.htm]. Although Lorence and Flynn (2006) noted that the panicles of these Dendrocnide plants on Pohnpei have stinging hairs characteristic of the Urticaceae family, this species of D. latifolia, as identified by Lorence and Flynn (2009:565, with a synonym of Laportea kusaiana Kaneh. listed “In Glassman”) may not be poisonous (also see Herrera et al. 2010).
Dendrocnide on Kosrae: In the lowlands of Kosrae Island, Dendrocnide latifolia (or D. kusiana?) can be found in the swamps dominated by the large Terminalia carolinensis Kanehira trees (see Allen et al. 2005); D. kusiana can also be found in the upland forests of Kosrae (e.g., see Maxwell 1982, Merlin et al. 1993). Many Kosraeans claim that the “stinging nettle” Dendrocnide tree, known as Elat on Kosrae is the only “tree” that has no known use on this island; this “non-use” is probably a function of its toxicity. We have briefly discussed this species here because it irritates at least some people’s skin, and consequently contact with this species should be avoided.
Note: Although no reports for use of D. latifolia (or D. kusiana) have been identified yet in Micronesia, in some areas of Southeast Asia, this species has reportedly been used medicinally; e.g., as a decoction of the leaves drunk to relieve a headache; having leaves rubbed on body bruises and aches to act as an analgesic; and the boiling of leaves of this plant which are then applied as a wash to relieve itchy skin (e.g., see: tropical.theferns.info/viewtropical.php?id=Dendrocnide+latifolia).