HOW TOUGH ARE SCLEROPHYLLS

Fracture toughness was estimated for a ‘least tough’ path in the leaves of woody species from three sclerophyllous plant communities. Most of the species from Mediterranean, tropical heath forest and lowland tropical rain forest habitats had very tough leaves, with toughness generally 600-1300 J rrT2, which is two to four times higher than soft- leaved tropical pioneer trees. The toughest leaf (2032 J m-2), Parishia insignis, came from the canopy of the lowland rain forest. Leaves from the shaded understorey of the rain forest did not appear any less tough than those from the canopy. © 1993 Annals of Botany Company.