Caladenia Tessellata
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National Recovery Plan for the Thick-lip Spider-orchid Caladenia tessellata Mike Duncan Prepared by Mike Duncan, Arthur Rylah Institute for Environmental Research, Department of Sustainability and Environment, Heidelberg, Victoria. Published by the Victorian Government Department of Sustainability and Environment (DSE) Melbourne, July 2010. © State of Victoria Department of Sustainability and Environment 2010 This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968. Authorised by the Victorian Government, 8 Nicholson Street, East Melbourne. ISBN 978-1-74242-006-6 This is a Recovery Plan prepared under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999, with the assistance of funding provided by the Australian Government. This Recovery Plan has been developed with the involvement and cooperation of a range of stakeholders, but individual stakeholders have not necessarily committed to undertaking specific actions. The attainment of objectives and the provision of funds may be subject to budgetary and other constraints affecting the parties involved. Proposed actions may be subject to modification over the life of the plan due to changes in knowledge. Disclaimer This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence that may arise from you relying on any information in this publication. An electronic version of this document is available on the Department of the Environment, Water, Heritage and the Arts website www.environment.gov.au For more information contact the DSE Customer Service Centre 136 186 Citation: Duncan, M. 2010. National Recovery Plan for the Thick-lip Spider-orchid Caladenia tessellata. Department of Sustainability and Environment, Melbourne. Cover photograph: Thick-lip Spider-orchid Caladenia tessellata Grantville, Victoria © Gary Backhouse 1 Contents SUMMARY...............................................................................................................................3 SPECIES INFORMATION.....................................................................................................3 DESCRIPTION............................................................................................................................3 DISTRIBUTION ..........................................................................................................................3 POPULATION INFORMATION .....................................................................................................4 HABITAT ..................................................................................................................................5 DECLINE AND THREATS ....................................................................................................5 RECOVERY INFORMATION ..............................................................................................6 RECOVERY OBJECTIVES ...........................................................................................................6 PROGRAM IMPLEMENTATION AND EVALUATION......................................................................6 RECOVERY ACTIONS AND PERFORMANCE CRITERIA................................................................6 MANAGEMENT PRACTICES.......................................................................................................7 AFFECTED INTERESTS ..............................................................................................................8 ROLE AND INTERESTS OF INDIGENOUS PEOPLE ........................................................................8 BIODIVERSITY BENEFITS ..........................................................................................................8 SOCIAL AND ECONOMIC IMPACTS ............................................................................................9 ACKNOWLEDGMENTS...............................................................................................................9 REFERENCES ............................................................................................................................9 PRIORITY, FEASIBILITY AND ESTIMATED COSTS OF RECOVERY ACTIONS 10 Figure 1. Current and former distribution of Caladenia tessellata.......................................... 4 Table 1. Population information for Caladenia tessellata....................................................... 4 2 Summary The Thick-lip Spider-orchid Caladenia tessellata is a small geophytic terrestrial orchid that is endemic to mainland south-eastern Australia, where it occurs in New South Wales and Victoria. About 19 populations are known, containing about 450 plants. The species has suffered a major decline in abundance throughout much of its range, largely due to loss of habitat. Major threats to remaining populations include disturbance to or destruction of plants and habitat, grazing and altered fire regimes. The Thick-lip spider Orchid is listed as Vulnerable under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999. It is also listed as Threatened under the Victorian Flora and Fauna Guarantee Act 1988, and Endangered under the New South Wales Threatened Species Conservation Act 1995. This national Recovery Plan for C. tessellata is the first recovery plan for the species, and details its distribution, habitat, threats and recovery objectives and actions necessary to ensure its long-term survival. Species Information Description The Thick-lip Spider-orchid Caladenia tessellata is a perennial terrestrial orchid emerging annually from an underground tuber. It has a single, sparsely hairy, linear-lanceolate leaf to 6 cm long. A slender, hairy, wiry flower stem to 30 cm tall bears one or two small (to 30 mm across) yellowish-green flowers with maroon stripes and suffusions. The perianth segments are up to 25 mm long, slender to broadly obovate, and tapering to short, fine points. The dorsal sepal is erect and incurved, the lateral sepals are deflexed and forward-pointing, and the petals are often strongly deflexed against the ovary. The labellum is broadly heart-shaped, the lateral lobes are thickened and obliquely erect and the margins entire (or occasionally with a few short teeth). The broad, central cluster of glossy purple to black, short, thick, clubbed calli are densely packed at the base, and often break up with 2 rows extending well onto the labellum mid-lobe. Caladenia tessellata is most similar to Caladenia cardiochila but can be distinguished by its usually smaller, duller flowers, often with more strongly deflexed perianth segments. In addition, the labellum generally has a broader, more open cluster of calli that sometimes breaks up towards the apex, with two rows extending onto the midlobe (description from Bernhardt 1993; Backhouse & Jeanes 1995; Bishop 1996; Jones 2006). The species is illustrated in Bishop (1996, plate 350) and Jeanes and Backhouse (2006, pg. 91). Little is known about the biology and ecology of C. tessellata. The species is dormant during summer, and dormancy is broken in response to soaking rains in autumn, with leaf emergence in late autumn- early winter. The plants flower from late September to early November and the flowers remain open for a few days to a few weeks, depending on pollination and climatic conditions. Fruits usually take 5– 8 weeks to mature following pollination, and plants reproduce solely from seed. The average longevity of C. tessellata plants is not known. Caladenia tessellata grows in a complex relationship with a mycorrhizal fungus that is necessary for seed germination, and provides some nutrients to the orchid. The type and degree of dependence upon the fungus, particularly of mature plants, are not known. Pollination is probably via sexual deception through the process of pseudocopulation (Peakall & Beattie 1996), with pollination by an undescribed black wasp of the genus Phymatothyninus observed at one site in New South Wales (GEC 2003). Response to fire is not well understood. Plants in several populations flower regularly in the absence of fire. In others, however, especially those growing in dense heath, flowering is much more sporadic and probably relies on periodic fire to remove surrounding vegetation and stimulate flowering. Caladenia tessellata was described in 1876 from plants collected at Hunters Hill, near Sydney NSW. There is some uncertainty as to whether the Victorian populations are C. tessellata or an undescribed species, and also whether the East Gippsland populations are the same taxon as the South Gippsland populations (D.L. Jones CPBR pers. comm.). However, until these taxonomic questions are clarified, all populations in this Recovery Plan will be treated as C. tessellata. Clarification of the taxonomy of all populations currently attributed to C. tessellata is an action in this Recovery Plan. Distribution The Thick-lip Spider-orchid is endemic to mainland south-eastern Australia, where it is distributed from the central coast of New South Wales to the Westernport region of southern Victoria (Figure 1), in the South East Coastal Plain, South East Corner, and Sydney Basin bioregions (sensu DEH 2000). The species usually occurs on or near the coast, but in southern New South Wales, extends well inland to 3 Braidwood.