J. Adelaide Bot. Gard. 17: 29-106 (1996) A REVISION OF THE GENUS KUNZEA (MYRTACEAE) I. THE WESTERN AUSTRALIAN SECTION ZEA1VUK H.R. Toelken State Herbarium of South Australia, Botanic Gardens of Adelaide North Terrace, Adelaide, South Australia 5000 Abstract Within Kunzea sect. Zeanuk, 21 species in three subsections are described and accompanied by discussion on their affinities based on morphological and anatomical evidence. Numerous natural putative hybrids are briefly discussed under the taxon placed first in the hybrid formulae. The paper includes publication of (a) 16 new taxa: sect. Zeanuk, subsect. Arborescentes, subsect. Floridae, subsect. Globosae, K acuminata, K.ciliata, K. cincinnata, K clavata, K. glabrescens, K. newbeyi, K. rostrata, K similis, K. spathulata, K. ericifolia (Sm.)Rchb. ex Heynh. subsp. subulata, K. micrantha Schauer subsp. hirtiflora and subsp. petiolata, and (b) one new combination: K. micrantha Schauer subsp. oligandra (Turcz.)Toelken. Introduction Schauer(1844) distinguished seven species of Kunzea from Western Australia in the first volume on plants collected by Preiss, and described an eighth in the second volume (Schauer 1848). Bentham (1867) rearranged the species and placed most of them in his sect. Eukunzea, which largely agrees with the present sect. Zeanuk except that it is no longer considered to be the typical section of the genus, because, when Kzinzea was conserved (Toelken 1981, 1981a), K capitata, from eastern Australia, was selected as the type of the genus. Reichenbach (1828) in his original use of the genus Kunzea referred to three species. Kunzea capitata was selected as the type in preference to K ericifolia and K corifolia (now K ambigua), because it has at all stages a capitate stigma, the distinguishing character used in the original publication. In the present circumscription of sect. Zeanuk all species are from Western Australia. Bentham's K. muelleri is excluded, although it shows a similar reduction of the placenta and number of ovules, because, in contrast to the western species, it has a well developed network of lateral veins in the leaves and does not shed the epidermis of its branches in a slough-like manner. A full discussion of the characteristics, their variation and affinities is included under each taxon. The sect. Zeanuk is treated separately because it represents a large clearly demarcated group in the genus. The reduced venation of the leaves and the small placenta with decreasing numbers of ovules show that it is an advanced group when compared with some species of sect. Kunzea. As it consists of such a uniform group of species it was considered to be more informative to defer a general discussion of the morphology and generic concepts until the publication of the latter more heterogeneous section. The terminology of the inflorescences, Le. the reduced conflorescence, the botryum, is used here as defined by Briggs & Johnson (1979). Attention is also drawn to the elongate late inflorescences sometimes observed, particularly in the subsections Arborescentes and Globosae, as they usually look quite different since their bracts enlarge and sometimes become almost leaf- like as for instance in K. ciliata. It is assumed that such a specimen of K recurva was described as K spicata (cf.typification of K recurva). The bracts and bracteoles subtending each flower often vary in size relative to the flower in different plants of the same species, but their shape was found to be a reliable characteristic of each species. The lower bracts grade into the shape of the perules or scales surrounding the terminal perennating buds from which the inflorescence or vegetative shoot develops. These perules, below the botrya and usually caducous, are described to distinguish them from the bracts but they often differ from perules surrounding terminal vegetative buds. 29 H.R. Toelken J. Adelaide Bot. Gard. 17 (1996) The bark of kunzeas is not easily described although some types are very distinctive. 'Early bark' refers to that of young branches up to 1 cm in diameter as it is often observed on herbarium specimen. The bark on old stems often differs markedly. As soon as the epidermis has worn off an often distinctive bark develops, usually with vertical splits along the branches at an early stage. The solid ridges thus formed particularly in corlcy bark rarely show obvious transverse splits. In fibrous bark the ridges are much less distinct partly because they consist of membranous layers obtaining their fibrous texture by the decay of the soft cells in between and, partly because successive layers often split at different points. The third type of bark, not found in the Western Australian species, splits more regularly vertically and transversely, resulting in chartaceous pieces of rectangular to square shape which are shed in their entirety or as parts with straight cleavages. This tessellated pattern often grades into the fibrous one which in turn can show intermediates with the corlcy bark. Keys are provided to the three subsections and in each of which there is a key to the species, subspecies and hybrids. Some species which could be mistaken as belonging to another subsection are included in both keys. For instance, K. acuminata and K. similis are included in the keys to both subsections Globosae and Floridae. Hybrids between species of different subsections have been included in both keys in order to draw attention to their existence. The conservation status of individual taxa could not be fully evaluated since the available data were insufficient. As it is not known how many of the duplicates of the types Schauer (1844) examined for descriptions of the species in Lehmann's compilation of the plants collected by Preiss, lectotypes have been selected. It was, however, found that he inscribed only one specimen of each collection cited, except in the case of K. micrantha/K. micromera where they represent different species (cf. typification of K. micromera). It is therefore highly likely that he had seen only the specimens he annotated and some of them should be holotypes, e.g. K pauciflora, as at least some duplicates (=isotypes) had been distributed by then. Most types were examined for this study and the few that could not be located are marked `n.v.'. Putative hybrids Hybrids between taxa were often observed and investigated in the field. Time was insufficient to attempt controlled artificial crossings. The shortcomings of morphological comparisons are realised; the object here is to create an awareness of the widespread existence of hybrids. Since they were largely found along disturbed road sides an increased occurrence must be expected with further interference with the vegetation. Many, but not all possible hybrid combinations between taxa described here have been recorded. Some species do not grow near to one another. In other cases, for instance K afrinis and K jucunda, although they often grow next to K micromera and K recurva, do not apparently cross with one another. Such cases of incompatibility seem to be rare as even these species hybridise with others in their own and other subsections. These individual cases do not seem to warrant studies of compatibility to obtain a wider understanding of relations. Pollen sterility was investigated in a few hybrids and was rarely found to exceed 10 to 20%, so it was not pursued as a means of identifying hybrids. The many hybrids recorded show that the pollination mechanism(s) within sect. Zeanuk cannot be very selective as even pink-, white- or yellow-flowered species seem to cross easily. The flowers of different species are morphologically very similar, especially in the spacial arrangement of the floral parts, differing mainly in size. The importance attributed here to hybrids might seem out of proportion to the numbers of plants found in a population if it were not that unusual plants, e.g. putative hybrids, are 30 J. Adelaide Bot. Gard. 17 (1996) Kunzeasect.Zeanuk(Myrtaceae) often selectively collected. As early as the late 1840s J. Drummond collected and transmitted specimens of what seem to have been a hybrid between K. montana and K. recurva, which Turczaninov (1852) described as K squarrosa (cf. 1(ii) K montana). That particular example shows the problem encountered with identifying hybrids and, closely linked to it, descriminating the species associated with them. Turczaninov based K squarrosa on the pink-flowered (hybrid) form, while a yellow-flowered specimen, just mentioned at the end of the description, is now lcnown to be one of the parental species, K. montana. Superficially the two specimens seem only to be colour forms of the same species. But this hybrid is an example in which a wide range of hybridisation with a complete range of backcrossing has resulted in forms so close to the original species that delimitation has become practically impossible. Without field studies of such a hybrid swarm it is impossible to distinguish between parent taxa and hybrids. A few such putative hybrid populations between different species were investigated, and the parents and the hybrids were eventually artificially delineated by what seems to be single character differences. It is purely a practical approach for localised situations which are at present rare. This procedure was followed only where at least one large hybrid swarm with extensive backrossing was found. Most putative hybrids are incompletely known from a limited number of plants or even 'intermediate herbarium specimens' which can not be reconciled with known variation of the parental taxa involved. As more information on some of the hybrids becomes available similar artificial delimitations will have to be decided. In others the state of information is at present based on few records with limited backcrossing that they are sufficiently discrete to be individually recognised. Further field work may show some such disparate hybrids to be local forms, possibly even infraspecific taxa, of one of the putative parents (e.g.