Survey of threatened plant species in South East Queensland biogeographical region queensland cra/rfa steering committee survey of threatened plant species in
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3.21 Marsdenia coronata Benth.3.21.1 SummaryMarsdenia coronata is restricted to south east Queensland where it has a scattered distribution from the Gunalda Range north of Gympie south to the Great Dividing Range near Killarney. It is recorded from three National Parks and from seven State Forest areas. There is no quantitative data on populations. However, it has been reported as being rare or occasional at collection sites. The distribution of Marsdenia coronata has a range of approximately 250 km and encompasses an area of occurrence of approximately 8800 km2. Current or perceived threats to the continued survival of M. coronata are considered to be loss of habitat to urban development and mining. 3.21.2 Species description and identificationThe genus Marsdenia is placed in the family Asclepiadaceae. The genus contains 250 species in Africa, Asia, Malesia, Central and South America, Melanesia and Australia (Forster 1996). In Australia there are approximately 33 species of which 28 are endemic and mostly found throughout the tropical and eastern Australia. They are commonly known as ‘milk vines’ because of the milky latex which oozes from the plant when damaged (Elliot & Jones 1993). The botanical description of Marsdenia coronata is as follows: Herbaceous slender wiry vine with white latex. Roots comprising a string of interconnected water-storage tubers. Stems cylindrical, up to 1.5 mm diameter, with 2 vertically spiralling bands of sparse to dense trichomes. Leaves petiolate; lamina linear-lanceolate, up to 5.5 cm long and 1 cm wide, discolorous, glabrous or with scattered trichomes below, venation obscure; apex acute; base rounded or cuneate; petioles up to 7 mm long; colleters 3 to 4 at lamina base. Inflorescence umbelliform. Flowers 4-5 mm long, 3-4 mm diameter. Corolla shallowly campanulate, yellow to yellow-green; tube 2.6-3 mm long, 3-3.2 mm diam.; lobes triangular, 1.6-2 mm long, 1.5-2 mm wide, internally glabrous. Corolline corona absent. Staminal corona of 5 auriculate, peltate lobes shorter than staminal column, entire; lobes 0.8-1 mm long. Anther appendages ovate to triangular. Style-head conical-globose. Fruit fusiform-ovoid, approximately 10 cm long, 15-16 mm diameter (Forster 1995, Forster 1996). For a more detailed description and illustration refer to Forster (1995 & 1996). Marsdenia coronata is closely related to M. brevis but differs from this species in its flower morphology and in having less discolorous leaves. The distinguishing features are set out in Table 3.21.1. Without flowering material it can be difficult to distinguish these two species. Table 3.21.1. Characters distinguishing Marsdenia coronata and Marsdenia brevis
3.21.3 Current conservation statusMarsdenia coronata is presently listed on the schedule of the Queensland Nature Conservation Act 1992 as “vulnerable wildlife”. The species has been assigned a national conservation status of E (endangered) by ANZECC (1993). It is recently been removed from the Schedule 1 of the Commonwealth Endangered Species Protection Act 1992. 3.21.4 Distribution and abundanceMarsdenia coronata was not surveyed during the present study. Details from Queensland Herbarium specimens of M. coronata are listed in Appendix 1.20. The species is known from thirty-four collections. M. coronata has a scattered distribution from the Gunalda Range north of Gympie to the Great Dividing Range near Killarney. Thirteen of the collections have been collected either on private land or road sides and most of these are within the vicinity of Ipswich. It is recorded from three National Parks (Main Range, Moogerah Peaks and Mount Coolum National Parks) and from seven State Forest areas (SF 215 Fty 821, SF 256 Fty 1190, SF 589 Fty 1657, SF 639 Fty 902, SF 792 Fty 1681, SF 944 Fty 1040 and SF 1239 Fty 1255). The is no quantitative data available on population sizes. However, it has been reported as being rare or occasional at collection sites. The distribution of Marsdenia coronata has a range of approximately 250 km and encompasses an area of occurrence of approximately 8800 km2. 3.21.5 HabitatMarsdenia coronata is most commonly found in open eucalypt forest and woodland communities on hillslopes and ridge tops at altitudes of 40 to 780 m. The soils are generally well drained, shallow, vary in texture from sandy, gravelly sand, loam to clay loam and are derived from sandstone or acid volcanic rocks. It has also been found or rocky outcrops along clifflines. The more frequent tree species recorded with this species are Eucalyptus fibrosa, E. carnea, Corymbia citriodora, C. henryi, E. acmenoides and E. propinqua. 3.21.6 Life history and ecologyThere have been no studies into the biology or autecology of Marsdenia coronata. The majority of the following information is extrapolated from our understanding of other species of Marsdenia. M. coronata is a perennial vine that reproduces by sexually produced seeds. There is no indication that the species can vegetatively reproduce. The longevity of the plants is unknown. Roots of this species are fleshy tuberous water storage organs in the form of a string of interconnected tubers to which the plant may die back in times of drought or fire (Forster 1995). M. coronata has been recorded flowering in January, February, April to June and October to December and fruiting in September. The species appears to be capable of flowering throughout the year but the main period of flowering is from October to February. Pollinators are suspected to be insects. Small beetles and small flies have been observed transferring pollinaria in other species of Marsdenia in Australia (Forster 1995). Fruits mature within 2 to 3 months after flowering and split to release many seeds. The light-weight seeds with tuffs of silky hairs are adapted for dispersal by air currents. The longevity and viability of the seed are unknown. Elliot and Jones (1993) report that Marsdenia seeds have a limited period of viability. This suggests that the species would not support a long-term seed bank in the soil. The response of M. coronata to fire is unknown but the above-ground biomass is probably killed by fire. It is capable of regenerating from its tuberous rootstock. 3.21.7 ThreatsThe lack of information about present populations levels of M. coronata and precise habitat requirements make it difficult to assess threats to this species. Large tracts of habitat have been cleared for urban development and mining in the Ipswich area. Clearing for urban development is continuing to occur and threatens a number of populations in the Ipswich area. 3.21.8 Management, research and conservation measuresField investigations are required to determine what populations remain and what would be the appropriate course of action for conserving the species. For the populations within conservation reserves and state forest lands appropriate management practices need to be put into place to ensure the long-term survival of M. coronata in the wild. However, at present there is a lack of ecological information about M. coronata which makes it impossible to assess what would be appropriate for the management of the habitat for the long term benefit of the species. Research is required into the fire ecology, reproduction biology and the population dynamics of the species. For those populations that occur on freehold land and road verges, liaison with land owners and local authorities should be undertaken to make them aware of the presence of the species and the importance of protecting the populations. Discussions should be undertaken with the land holders in regard to protecting the areas with Conservation Agreements under the Queensland Nature Conservation Act 1992. |