National Recovery Plan for the
Enigmatic Greenhood
Pterostylis aenigma

Mike Duncan

Prepared by Mike Duncan, Department of Sustainability and Environment, Victoria.

Published by the Victorian Government Department of Sustainability and Environment (DSE) Melbourne, 2008.

© State of Victoria Department of Sustainability and Environment 2008
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 978-1-74208-713-9

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. 2008.  National Recovery Plan for Enigmatic Greenhood Pterostylis aenigma.  Department of Sustainability and Environment, Melbourne.

Cover photograph: Enigmatic Greenhood Pterostylis aenigma by Mike Duncan.

TABLE OF CONTENTS

Summary
Species Information
Description and taxonomy
Distribution and population
Habitat
Decline and threats
Recovery Information
Existing conservation measures
Strategy for recovery
Recovery objectives
Program implementation
Program evaluation
Recovery actions, performance criteria and priorities
Affected interests
Role and interests of Indigenous people
Benefits to other species/ecological communities
Social and economic impacts
Management Practices
Acknowledgments
Bibliography
Estimated Cost of Recovery Actions

Figure 1.  Distribution of the Enigmatic Greenhood

Summary
The Enigmatic Greenhood is a small terrestrial orchid endemic to the mountains of eastern Victoria, where it is known from just a single site containing fewer than 100 plants.  The species is listed as Endangered under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).  Although the single population occurs within the Alpine National Park, it is threatened by grazing, weed invasion and sedimentation of habitat following a severe wildfire in 2003.  This national Recovery Plan for the Enigmatic Greenhood is the first recovery plan for the species, and details the species' distribution and biology, conservation status, threats, and recovery objectives and actions necessary to ensure its long-term survival.
Species Information
Description and taxonomy
The Enigmatic Greenhood Pterostylis aenigma D. L. Jones & M. A. Clem. is a terrestrial, deciduous herb growing to 30 cm tall, with a basal rosette of 3–4 leaves and a large, leafy floral bract.  The single, terminal flower is translucent white with green stripes and reddish-brown tonings on the petals and lateral sepals.  The dorsal sepal and petals are combined to form a hood-like galea that is erect for three-quarters of its length before curving forward, ending in an obliquely deflexed, pointed tip.  The lateral sepals are erect, the free points extending above the galea.  Plants are dormant in late summer and early autumn, and emerge from spherical subterranean tubers, probably in mid-late autumn, in response to soaking rains.  Flowering occurs in November and December, after which plants die back and become dormant again (description from Jones & Clements 1993; Backhouse & Jeanes 1995).
There is some uncertainty as to the correct taxonomic status of the Enigmatic Greenhood.  It was originally described as a species (Jones & Clements 1993).  However, there was a suspicion that it may have actually been a naturally occurring hybrid between the Leafy Greenhood Pterostylis cucullata and Sickle Greenhood Pterostylis falcata (Backhouse & Jeanes 1995), both of which grow near the P. aenigma population.  The Enigmatic Greenhood is intermediate in appearance between the putative parent taxa, and it was subsequently relegated to hybrid status (Jones 2006).  Clarification of the taxonomic status of the Enigmatic Greenhood is an action proposed in this Recovery Plan.
Distribution and population
The Enigmatic Greenhood is endemic to eastern Victoria.  It is known from only a single location, about 10 km north of Omeo, at an altitude of 950 m ASL, in the Alpine National Park (Australian Alps bioregion sensu DEH 2000).

Figure 1.  Distribution of the Enigmatic Greenhood
The population is thought to number fewer than 100 plants, confined to an area of about 0.5 ha.  Estimating total population size in this species is difficult, as it cannot be reliably identified when not in flower, due to the presence of other species of Pterostylis that have similar-looking basal rosettes.  The Enigmatic Greenhood can also reproduce vegetatively by tuber multiplication, so it is not certain how many plants actually represent separate genetic entities.
Maps showing the distribution of the Enigmatic Greenhood are available from the Department of Sustainability and Environment.
Habitat
The Enigmatic Greenhood occurs on a seasonally waterlogged alluvial flat along a small creek within grassy open forest, on grey to brown clay loam soil.  The overstorey is dominated by Mountain Swamp Gum Eucalyptus camphora subsp. humeana with an understorey of Blackwood Acacia melanoxylon.  The ground layer is dominated by grasses, lilies and sedges, including Tall Mountain Tussock-grass Poa helmsii, Fen Sedge Carex gaudichaudiana, Tasman flax-lily Dianella tasmanica and Mother Shield-fern Polystichum proliferum.  Inter-tussock species include Forest Buttercup Ranunculus plebeius, Prickly Starwort Stellaria pungens, Alpine Cotula Cotula alpina, Kidney–weed Dichondra repens, Self-heal Prunella vulgaris, Ivy-leaf Violet Viola hederacea and Rough Cranesbill Geranium species.  Introduced plants include English Broom Cytisus scoparius, Sweet Briar Rosa rubiginosa, Blackberry Rubus fruticosus spp. agg, thistle Cirsium species, Yorkshire Fog Grass Holcus lanatus and White Clover Trifolium repens var. repens.
Decline and threats
The Enigmatic Greenhood was only discovered within the last 20 years, and is known from just a single location, so its previous distribution and abundance are not known.  Since discovery, the population has always been small, probably fewer than 100 plants, with a peak of 80 flowering plants recorded in 2002.  At that time, grazing and weed invasion were considered major threats.
In January 2003, the area was burnt in a severe wildfire.  One month later, 80 mm of rain fell on the catchment in just one hour, the downpour washing tonnes of soil from the still bare hillsides into the alluvial flat containing the P. aenigma population.  Although the site was covered with 20 cm of silt, 50 flowering plants were recorded in December 2003.  However, only 10 plants flowered in 2004, and none in the three years since.  While the species apparently survived the short-term effects of siltation in the first year, the subsequent decline in flowering is thought to be mostly due to the very dense regeneration of both native plants and weeds occurring on the site.  English Broom is the most serious weed threat, with other weeds including Sweet Briar, Blackberry, Yorkshire Fog Grass and White Clover also problematic.  Whether the decline in flowering rate represents a real decline in plant numbers is not known.  The 2003 wildfire and subsequent heavy rain clearly illustrates the vulnerability of single, small populations to stochastic events.
Grazing from native herbivores (Common Wombat, macropods and possibly invertebrates) is a problem, as flowers and fruits are frequently lost to predation.  However, light grazing of the site by native herbivores is likely to be beneficial to the Enigmatic Greenhood, through reduction in competition from grasses, which otherwise quickly develop into dense swards in the absence of grazing.
The species may also be at risk from long-term drying out of its habitat.  The extensive eucalypt seedling germination following the 2003 wildfire may alter site hydrology for years to come through increased transpiration leading to greatly reduced run-off.  The increased temperatures, increased evaporation rates and decreased rainfall expected to affect south-eastern Australia with climate change brought about by global warming are also likely to lead to further loss of habitat, as the seasonally wet site favoured by the species gradually dries out.
Other potential threats include innappropriate fire regimes and track construction or realignment at the site.
Recovery Information
Existing conservation measures
A number of conservation measures have been undertaken to protect the Enigmatic Greenhood, including:
•	Caging of some plants to protect them from grazing.
•	Weed control, especially of English Broom, at the site, undertaken by Parks Victoria and assisted by the 'Friends of the Mitta Mitta' community group.
•	Erosion control to protect the site from continuing soil movement from the surrounding hills.
•	Annual monitoring, undertaken by the the Bairnsdale Field Naturalists Club.
•	Searches of nearby suitable habitat (although no new populations have been found).
Strategy for recovery
The first issue to address in recovery of the Enigmatic Greenhood is its taxonomic status, the determination of which may influence subsequent recovery actions.  Investigation of ecology of the species, including life history, flowering, fruiting, seed germination, seedling establishment, longevity, length of dormancy, population structure, demography, pollination biology, mycorrhizal relationships and response to fire, is urgently required for recovery management.  As the species is known only from a small number of plants at a single location, establishing a population in cultivation for risk management is a high priority.  This population will also serve as the basis for establishing new populations in the wild, which will be required for ultimate recovery of the Enigmatic Greenhood.
Recovery objectives
The overall objective of recovery is to minimise the probability of extinction of the Enigmatic Greenhood in the wild and to increase the probability of populations becoming self-sustaining in the long term.
Within the duration of this Recovery Plan, the specific objectives for the recovery of the Enigmatic Greenhood are to:
•	Determine taxonomy, distribution, abundance and population structure
•	Identify habitat requirements
•	Manage threats to populations
•	Identify key biological functions
•	Determine growth rates and viability of populations
•	Establish a population in cultivation
•	Establish new populations in the wild
•	Build community support for conservation
Program implementation
This Recovery Plan guides recovery actions and will be managed by the Department of Sustainability and Environment.  A Threatened Flora Recovery Team, consisting of scientists, land managers and field naturalists will be established to oversee threatened flora recovery in Victoria in general.  Technical, scientific, habitat management or education components of the Recovery Plan will be referred to specialist sub-committees on research, in situ management, community education and cultivation.  Regional Recovery Teams will be responsible for preparing work plans and monitoring progress toward recovery.
Program evaluation
The Recovery Team will be responsible for annual assessments of progress towards recovery.  This Recovery Plan will be reviewed within five years of the date of its adoption under the EPBC Act.

Recovery actions, performance criteria and priorities

Action	Description	Performance Criteria	P*	
Specific objective 1:  Determine taxonomy, distribution, abundance and population structure	
1.1	Clarify taxonomy using genetic analysis to determine if P. aenigma is a species or natural hybrid.
Responsibility:  RBG	Determination of taxonomic status.	1	
1.2	Determine the area, extent, number, size and structure of the population, and estimation of population change.
Responsibility:  DSE, PV	Data on area occupied/number of plants.	2	
Specific objective 2:  Identify habitat requirements	
2.1	Survey habitat and collect floristic and environmental information relevant to community ecology and condition.
Responsibility:  DSE, PV	Habitat critical for survival identified and defined.	2	
2.2	Identify and survey potential habitat, using ecological and bioclimatic information that may indicate habitat preference.
Responsibility:  DSE	Predictive model for potential habitat developed and tested.	2	
Specific objective 3:  Manage threats to populations	
3.1	Control pest plants.
Responsibility:  DSE, PV	Measurable reduction in area and impact of weed infestation.	1	
3.2	Investigate impact of grazing and if required protect plants from predation.
Responsibility:  DSE	Measurable increase in flowering rate and fruit production.	1	
3.3	Protect site from erosion and soil movement.
Responsibility:  DSE, PV	No further movement of soil/sediment onto the P. aenigma site.	1	
3.4	Manage microhabitat for seedling recruitment.
Responsibility:  DSE, PV	Measurable increase in seedling recruitment.	1	
Specific objective 4:  Determine the growth rates and viability of populations	
4.1	Measure population trends/responses against recovery actions.
Responsibility:  DSE, PV, BFNC	Population Viability Analysis completed for known population.	1	
Specific objective 5:  Establish a population in cultivation	
5.1	Hand pollinate plants and collect seed.
Responsibility:  DSE, PV	Seed capsules developed and seed collected.	1	
5.2	Establish a seed bank and determine seed viability.
Responsibility:  RBG	Seed in long term storage and viability determined.	2	
5.3	Establish plants in cultivation to safeguard against decline/extinction and for translocations.
Responsibility:  RBG, NOGN	Effective propagation techniques developed, and at least 50 mature plants in cultivation.	1	
Specific objective 6:  Establish new populations in the wild	
6.1	Evaluate and select suitable translocation sites for estbalishing new populations.
Responsibility:  DSE, Recovery Team	Criteria for site suitability identified; at least one suitable site selected; translocation plan prepared.	1	
6.2	Prepare site to receive translocated plants.
Responsibility:  DSE	Site is defined, protected and managed to maximise survival of seeds/plants.	1	
6.3	Introduce and monitor plants.
Responsibility:  DSE, BFNC	Survival rate of translocated plants meets defined success criteria.	1	
Specific objective 7:  Build community support for conservation	
7.1	Encourage and facilitate community group involement in the recovery activities.
Responsibility:  DSE, PV	Community group participation in recovery activites eg. monitoring, threat control.	3	
Abbreviations: BFNC–Bairnsdale Field Naturalists Club; DSE–Department of Sustainability and Environment, Victoria; NOGN–Native Orchid Growers Network; PV–	Parks Victoria; RBG–Royal Botanic Gardens, Melbourne

Affected interests
The only known population of the Enigmatic Greenhood occurs within the Alpine National Park, and management of this population is the responsibility of Parks Victoria and the Department of Sustainability and Environment.  The Royal Botanic Gardens Melbourne will also be involved in recovery of the species, as well as community groups including the 'Bairnsdale Field Naturalists Club', 'Friends of the Mitta Mitta' and the 'Native Orchid Growers Network'.
Role and interests of Indigenous people
Indigenous communities on whose traditional lands the Enigmatic Greenhood occurs will be advised, through the relevant DSE Regional Indigenous Facilitator, of this Recovery Plan.  Indigenous communities will be invited to be involved in the implementation of the Recovery Plan.
Benefits to other species/ecological communities
The recovery plan includes a number of potential biodiversity benefits for other species and vegetation communities in Victoria.  Principally, this will be through the protection and management of habitat.  The adoption of broad-scale management techniques and collection of baseline data will also benefit a number of other plant species growing in association with P. aenigma, particularly those species with similar life forms and/or flowering responses.
The recovery plan will also provide an important public education role as orchids have the potential to act as ‘flagship species’ for highlighting broader nature conservation and biodiversity issues such as land clearing, grazing, weed invasions and habitat degradation.  Germination and cultivation techniques developed during the recovery phase will be of use for other threatened orchids elsewhere in southeast Australia while the requirement to recover species across state boundaries will better develop working relationships between state departments on a broader range of biodiversity conservation issues.
Social and economic impacts
The implementation of this recovery plan is unlikely to cause significant adverse social and economic impacts, as the single known location where the species occurs is in a national park.  Protection measures for the Enigmatic Greenhood will not impact on current recreational or economic uses of the area.
Management Practices
On-ground site management will aim to mitigate threatening processes and thereby insure against extinction.  Major threats requiring management include accidental destruction, competition from pest plants, erosion/sedimentation and inappropriate fire regimes.  A range of strategies will be necessary to alleviate these threats including protective fencing, weed control, erosion control and fire management.  In addition, searches of known and potential habitat should continue to better define the distributions and size of populations.
The Recovery Plan also advocates strategies to fill some of the major gaps in our knowledge to date.  These include an understanding of the mechanisms underlying recruitment and regeneration.  Successful in situ population management will be founded on understanding the relationships between the Enigmatic Greenhood and associated flora, and its response to environmental processes.  Demographic censusing will be necessary to gather life history information and to monitor the success of recovery actions.
In addition to the above, ex situ conservation measures will be required and will include seed storage and plant cultivation.  Translocations to establish new populations will be required for ultimate recovery.  Community participation in recovery actions will be sought, particularly in regard to implementation of on-ground works.
Management practices required for conservation of Enigmatic Greenhood include:
•	Control of pest plants and animals.
•	Investigation of the biology and ecology of the species to enable better targeted conservation management actions.
•	Maintenance of ex-situ populations.
•	Establishment of new populations at protected sites.
Acknowledgments
I would like to thank the following people who provided information, critical comment or assisted with field work during the preparation of this recovery plan: Gary Backhouse, Mick Bramwell, David Cheal, Fiona Coates, Adrian Moorrees and Andrew Pritchard (Dept. of Sustainability and Environment); Mike Dower (Parks Victoria); Dean Rouse (Australian National University, Canberra); and James Turner (Bairnsdale Field Naturalists Club).
Bibliography
Backhouse, G.N. and Jeanes, J.A. 1995.  The Orchids of Victoria.  The Meigunyah Press, Melbourne.
DEH 2000.  Revision of the Interim Biogeographic Regionalisation of Australia (IBRA) and the Development of Version 5.1. - Summary Report.  Department of Environment and Heritage, Canberra.
Jones, D.L. 2006.  A Complete Guide to Native Orchids of Australia.  New Holland, Frenchs Forest.
Jones, D.L. and Clements, M.A. 1993.  New species of Pterostylis R. Br. (Orchidaceae) from Victoria and New South Wales.  Muellaria 8(1): 73–83.

Estimated Cost of Recovery Actions

Action	Description	Cost $	
		Year 1	Year 2	Year 3	Year 4	Year 5	Totals	
1:  Determine distribution, abundance and population structure	
1.1	Clarify taxonomy	8,000	5,000	0	0	0	13,000	
1.2	Determine area, extent, structure	7,000	7,000	7,000	7,000	7,000	35,000	
2:  Identify habitat requirements	
2.1	Survey known habitat	10,000	10,000	0	0	0	20,000	
2.2	Identify & survey potential habitat 	0	5,000	10,000	10,000	0	25,000	
3:  Manage threats to populations	
3.1	Control pest plants	15,000	10,000	5,000	5,000	5,000	40,000	
3.2	Investigate & control grazing	5,000	2,000	2,000	2,000	2,000	13,000	
3.3	Control erosion	5,000	5,000	2,000	2,000	2,000	16,000	
3.4	Manage microhabitat	5,000	5,000	2,000	2,000	1,000	15,000	
4:  Determine growth rates and viability of populations	
4.1	Measure population trends	10,000	10,000	10,000	10,000	10,000	50,000	
5:  Establish a population in cultivation	
5.1	Hand pollinate and collect seed	2,000	2,000	2,000	2,000	2,000	10,000	
5.2	Establish a seed bank	5,000	2,000	1,000	1,000	1,000	10,000	
5.3	Establish plants in cultivation	2,000	2,000	3,000	3,000	3,000	13,000	
6:  Establish new populations in the wild	
6.1	Evalutae & select suitable site	5,000	5,000	0	0	0	10,000	
6.2	Prepare site	0	1,000	5,000	1,000	0	7,000	
6.3	Introduce and monitor plants	0	0	0	5,000	5,000	10,000	
7:  Build community support for conservation	
7.1	Community group involvement	2,000	2,000	1,000	1,000	1,000	7.000	
Totals	$81,000	$73,000	$50,000	$51,000	$39,000	$294,000