Intramarginal Vein Research Articles

COMPARATIVE ANATOMY AND MORPHOLOGY OF PS1LOXYLON AND HETEROPYXIS, AND THE SUBFAMILIAL AND TRIBAL CLASSIFICATION OF MYRTACEAE

SummaryEvidence from wood, leaf, and floral anatomy, from palynology, and from reconsideration of vegetative and reproductive morphology fully support (1) the placement of Heteropyxis by Fernandes (1971), Stern & Brizicky (1958), and Weberling (1963) in Myrtaceae/Leptospermoideae on the basis of organography, palynology, and petiole and wood anatomy, and (2) the placement of Psiloxylon by van Tieghem (1904) in Myrtaceae on the basis of especially vegetative anatomy. Diagnostic myrtaceous characters shared by both genera include: entire, simple, gland‐dotted, penninerved leaves wth intramarginal veins; rudimentary stipules (Heteropyxis only); pentamery; nectary lining floral tube; imbricate, persistent calyx; many pollen features; sunken styles; baccate or capsular fruits (resp. Psiloxylon and Heteropyxis); exalbuminous seeds; bicollateral bundles; secretory cavities in all aerial organs, including the anthers; unilacunar one‐trace nodes; arcuate petiolar bundles with sclerenchymatous sheaths (only in lamina of Psiloxylon); vestured pits; wood fibers with distinctly bordered pits; and tannin. Both genera, however, differ from many, but not all Myrtaceae in having: alternate leaves; unisexual, but bisexual‐appearing flowers (only the staminate in Psiloxylon); perigyny; few stamens (Psiloxylon diplostemonous, Heteropyxis essentially obdiplostemonous); short style and divided stigma (Psiloxylon only); cancellate seed (Psiloxylon only); and such wood characters as septate, crystalliferous fibers and lack of vasicentric tracheids in Psiloxylon, and lack of axial parenchyma in Heteropyxis. The segregates Heteropyxidaceae and Psiloxylaceae should thus be included in Myrtaceae. The foregoing ensemble of characters conclusively excludes for Heteropyxis any assignment to Rhamnaceae or Rutaceae, for Psiloxylon any assignment to Bixaceae sensu lato, Flacourtiaceae, or Guttiferae, and for both genera an assignment to Lythraceae. Because it would be anomalous in either of the two traditional myrtaceous subfamilies, Psiloxylon is best treated as a new subfamily in Myrtaceae. Finally, since Leptospermeae and Chamaelaucieae differ as much from each other as either does from Myrteae, Chamaelaucieae should be elevated to subfamilial status in Myrtaceae. The family Myrtaceae thus has four subfamilies: Myrtoideae, Psiloxyloideae, Leptospermoideae, and Chamaelaucioideae. An addendum discusses Briggs & Johnson's (1979) detailed paper on vegetative and especially reproductive structure of Myrtaceae.

Botanical contributions of the Northern Australia regional survey. I. Studies on Northern Australian species of Eucalyptus

This is the first botanical contribution from the C.S.I.R.O. Northern Australia Regional Survey. Revised accounts of 50 species with discussions on taxonomy, distribution, and typification of names are the result of a partial revision of the genus Eucalyptus as represented in the northern part of Australia; keys to two groups particularly studied are given. All the 42 species known from the northern part of the Northern Territory are treated, with three keys to their identification; the first of these is based on characters observable in the field, the second on hand specimens with buds and flowers, and the third on hand specimens with fruits only. New criteria for the discrimination of species have been used, and some examples of their application are shown graphically; these include the number of lateral veins in the leaf, the ratio of its length to its breadth, and (to some extent) the exact distance of the intramarginal vein from the margin and the shape of the free part of the calyx-tube of the flower. The juvenile stages, flowers, fruits, and seeds are described for the first time for some species. Types of all names, with the herbaria in which they are to be found, are cited, with reference to published figures, some of which appear for the first time in this paper. Several lectotypes are designated, and the guiding principles adopted for their selection are described. Citations of specimens are restricted to those collected in 1946-9 on the Northern Australia Regional Survey, to types, new records, and some critical collections. Distribution maps of 51 species are based on all specimens examined. Plates from photographs illustrate the characteristic habit of some species, the deciduous nature of some, a few characteristic barks, various type specimens and some other specimens cited in taxonomic discussions. The status of about 160 names was investigated. Among others, E. clavigera A. Cunn. ex Schau., E. polycarpa F. Muell., E. terminalis F. Muell., E. foelscheana F. Muell., and E. racernosa Cav. are shown to have been originally applied to species different from those currently passing under these names. Many names are treated as synonyms on taxonomic grounds, 24 of them for the first time. All nomenclatural changes are summarized in two tables. One new species, E. porrecta S. T. Blake, and one new combination, E. gilbertensis (Maiden & Blakely) S. T. Blake, are proposed. The following species are new records for the areas mentioned: E. Izerbertiana and E. cliftoniana (Northern Territory) ; E. aspera and E. ferruginea (Queensland) ; E. bigalerita and E. patellaris (Western Australia) ; and E. dichromophloia (South Australia). In an appendix, the graphical methods and distribution maps are discussed and some remarks made on the phylogeny and history of distribution of the genus.