The anatomy of the barks of Leptospermoideae

Abstract

The anatomy of the barks of 61 species of the tribe Leptospermoideae of the family Myrtaceae, principally from Australia, has been studied. The following anatomical features in particular have been described: type and arrangement of sclerenchyma, type and distribution of crystals, silica, oil glands, sieve tube type, fibre dimensions, periderm, and rhytidome. A key for the identification of the species and/or groups of species described has been derived from the bark anatomy. The bark anatomy would appear to be superior to the wood anatomy for the separation of the species of the tribe. The relationship between the bark anatomy and the taxonomy of the tribe is discussed. Support for the separation of Choricarpia subargentea and C. leptopetala from both Syncarpia and Tristania is given. Tristania neriifolia appears to be distinctly different from other Tristania spp. and re-examination of the species is suggested. Samples of Metrosideros sp. from Indonesia have been found to have the characteristics of Xanthostemon and re-examination of the genus of this species is also suggested. Oil glands have been found to be restricted to the genera Eucalyptus, Syncarpia, and Xanthostemon. Resorption of crystals has been found in the outer phloem of a number of species. Casparian thickening of the cell walls of the suberized phellem in Callistemon and Melaleuca has been confirmed.