Correa Alba Andrews Var. Rotundifolia DC
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Correa alba Andrews var. rotundifolia DC. (Rutaceae): an old name for a newly recognised variety endemic to south-eastern Tasmania B.-K. Choia,b,c, and M. F. Durettoa a Tasmanian Herbarium, Tasmanian Museum & Art Gallery, Private Bag 4, Hobart, Tasmania 7001, Australia b School of Plant Science, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia c Present address: Laboratory of Plant Systematics, Department of Biology, Kyung Hee University, Seoul 130-701, South Korea; e-mail: [email protected] Introduction Abstract Correa alba Andrews (Rutaceae), though easily identifiable, has had The name Correa alba Andrews a complicated taxonomic history. The genus and species were first var. rotundifolia DC. (Rutaceae) is resurrected for a newly recognised described by Andrews (1798) from material that was grown from variety endemic to south-eastern seed collected by Sir Joseph Banks from Port Jackson [Sydney] (Table Tasmania. Mazeutoxeron rufum Labill., 1). Soon after this Salisbury (1808) indicated that he had never seen the basionym, is lectotypified. A plants with petals that were entirely white and so thought the specific key to the three varieties of C. alba epithet, alba, was inappropriate. He erected the new name C. cotinifolia is provided as are descriptions and notes. Salisb. which, as C. alba is given in synonymy under var. α, is illegitimate. Labillardiere (1800) described Mazeutoxeron Labill. and M. rufum Labill. Muelleria 26(2): 45-53 (2008) from material he collected in south–eastern Tasmania in 1793 (Table 1). Ventenat (1803) transferred this species to the genus Correa Andrews and later, Candolle (1824) published it as a variety of C. alba: C. alba var. rotundifolia DC. The epithet ‘rotundifolia’ was again used by Lindley (1838) when he described C. rotundifolia Lindl. This taxon was based on material collected from Glenelg River [western Victoria] by T.L. Mitchell in 1836. Bentham (1863) reduced this species to a variety of C. alba, Correa alba var. rotundifolia (Lindl.) Benth., an illegitimate combination as it is a later homonym of C. alba var. rotundifolia DC. (Table 1). Wilson (1961) determined that the taxon described by Lindley warranted taxonomic recognition and so created the new name C. alba var. pannosa Paul G.Wilson based on C. rotundifolia. Correa alba is found in near-coastal areas from Kangaroo Island [requires confirmation – see Distribution under var. pannosa] and the Southern Lofty Region (South Australia) through southern Victoria and to the North Coast of New South Wales. It is also found on the islands of the eastern side of Bass Strait and has a patchy distribution on the northern and eastern coasts, and nearby islands, of the island of Tasmania. Currently two varieties are recognised (see Wilson 1961, Muelleria 45 Choi & Duretto 1998; Anderson 1986; Duretto 1999; Anonymous 2001; Materials and methods Weston & Harden 2002; Ross & Walsh 2003; Walsh & Research was carried out on both herbarium specimens Stajsic 2007). Correa alba var. alba is found in New South and on material collected in the field. Herbarium material Wales, eastern Victoria and Tasmania. Correa alba var. (c. 200 specimens) from the Tasmanian Herbarium pannosa is found in western Victoria and south-eastern (HO), the National Herbarium of Victoria (MEL) and the South Australia. National Herbarium of Australia (CANB) was studied. Correa alba var. alba shows some variation which This covered the full geographical distribution of C. alba. was noted by Wilson (1961) who noted that plants Plant collections of C. alba were made in south-eastern in the north had leaves that were ‘thinly tomentose Tasmania, in the South Arm area (two populations) and below’ while plants from further south had leaves that the Tasman Peninsula (three populations). Specimens were ‘thickly ferruginous tomentose’ (see Fig. 1). Typical from three to five widely spaced plants were collected var. alba is found on the East Coast of Tasmania north from each population sampled. Specimens have been from Triabunna and across northern Tasmania, on the lodged at the Tasmanian Herbarium. The typical form islands of eastern Bass Strait through eastern Victoria of C. alba var. alba was observed in the field by BKC at and in coastal New South Wales. The abaxial surface Swansea, Oyster Bay, Freycinet Peninsula (Tas.) and of the leaves has a dense indumentum of stellate hairs Jervis Bay (ACT). that are mostly sessile (Fig. 1A-D). A form from south- For Scanning Electron Microscopy (SEM), leaves of eastern Tasmania, the Tasman and Forestier peninsulas, selected specimens were mounted on aluminium stubs the South Arm area (near Hobart) and Bruny Island, is using double-sided or carbon tape with carbon paint. easily distinguishable in that it has large hairs that are Specimens were then coated with platinum using a stalked (Fig. 1I-L). There is a 50 km wide gap, between JFC–1100E ion sputtering device, and examined and Dunalley and Triabunna, separating the two forms. photographed at 7kV and 10kV using HITACHI S–4700. This second form from the south-east of Tasmania, Terminology for describing the hairs is complex with the stalked hairs, matches the type material of and not fully covered in e.g. Hewson (1988). In C. alba Mazeutoxeron rufum and so the name C. alba var. var. pannosa and var. rotundifolia the stellate hairs rotundifolia DC. can be applied to it (see Typification are stalked. In the latter the stalk is usually smooth under this variety). Correa alba var. rotundifolia is similar (i.e. lacking outgrowths) and terminates in a tuft of in appearance to C. alba var. pannosa as both have multidirectional rays. In var. pannosa the stalk often large stalked hairs (Fig. 1E-L), but the stalks and rays of has a number of simple rays (similar to those of the the hairs are shorter in var. rotundifolia. Also the stalks terminal tuft) emerging from it. These simple rays are of the hairs of C. alba var. pannosa often have a large often clustered and so the hair often looks like two to number of rays along their length, whereas they are four stalked stellate hairs placed on top of each other. smooth and rayless except at the tip in var. rotundifolia As such it would be misleading to call the hair dendritic (see key to varieties below). (branched like a tree) or branched (see Fig. 1). Table 1: Nomenclatorial history of Correa alba Name Date Basionym Accepted name Correa alba Andrews 1798 C. alba C. cotinifolia Salisb. 1808 C. alba Andrews C. alba Mazeutoxeron rufum Labill. 1800 C. alba var. rotundifolia DC. C. rufa (Labill.) Vent. 1803 M. rufum Labill. C. alba var. rotundifolia DC. C. alba var. rotundifolia DC. 1824 M. rufum Labill. C. alba var. rotundifolia DC. C. rotundifolia Lindl. 1838 C. alba var. pannosa C. alba var. rotundifolia (Lindl.) Benth. 1863 C. rotundifolia Lindl. C. alba var. pannosa C. alba var. pannosa Paul G.Wilson 1961 C. rotundifolia Lindl. C. alba var. pannosa 46 Vol 26(2) 2008 Correa Alba Taxonomy Region (South Australia) through southern Victoria and to the North Coast of New South Wales. In Tasmania it Correa alba Andrews, Bot. Repos. 1: t.18 (1798) is found on the islands on the eastern side of Bass Strait Correa cotinifolia Salisb., Parad. Lond. t. 100 (1808), and has a patchy distribution on the northern and nom. illeg., based on above. eastern coasts of the Tasmanian mainland and offshore Type: NEW SOUTH WALES. Port Jackson, raised in islands. It is apparently absent from King Island. 1793 from seeds given by J. Banks to J. Vere (holotype Habitat: The species occurs in near coastal situations [see Wilson 1961, p. 38]: Bot. Repos. 1: t. 18). on foredunes, cliffs and headlands. It is found growing Rounded, spreading, multi-stemmed, woody on both calcareous and siliceous substrates (sand and/ shrub to 3 m high, to 4 m in diameter, large plants or rock) in heath or woodland. often supported by other vegetation; stems stellate Notes: Correa alba readily hybridises with other tomentose, glabrescent with age; stellate hairs white species of Correa (see Wilson 1961; Anderson 1986; to red-brown. Leaves simple, petiolate; petiole 2–8 mm Duretto 1999). long; lamina elliptic to obovate to orbicular, rarely ovate Infraspecific variation: Three varieties are or lanceolate or oblanceolate, 5–46 mm long, 2.5–28.5 recognised for the species. The rank of variety is mm wide, discolorous; tip acute to obtuse; margins appropriate (as opposed to subspecies and species) entire; adaxial surface greyish green, with a sparse to as the distinctions between the taxa are based on few moderately dense indumentum of stellate hairs that characters, and these mostly pertaining to hairs, and are often eventually deciduous; abaxial surface densely some problematic specimens do exist (see Notes under white or greenish white or reddish brown, stellate var. pannosa). tomentose. Flowers axillary, often solitary though up to Conservation status: Overall the species 5 flowers per inflorescence not uncommon and then appears to be secure with the typical variety secure usually one flower opening at a time; peduncles to 9 and the other two being rare but found in reserves (see mm long; bracts leaf–like; bracteoles minute; pedicels below). Correa alba is used extensively in horticultural 0.5–6.5 mm. Calyx cuplike, 2.5–7 mm long, truncate and revegetation plantings. In Hobart, the two to slightly dentate to dentate or broadly lobed. Petals Tasmanian varieties (var. alba and var. rotundifolia) partially fused in bud, free at anthesis, white or rarely are both available and commonly used, sometimes pink, 7–17 mm long, 1.5–5 mm wide, adaxial surface in mixed plantings, even though var. alba is not glabrous, abaxial surface sparsely to densely stellate indigenous to the area.