Acianthus caudatus
Mayfly orchid
Overview
Acianthus caudatus is a small deciduous terrestrial orchid that grows from an underground tuber and reaches 10-30 cm (4-12 in) tall in flower, native to south-eastern Australia. Each plant produces a single heart-shaped leaf that lies close to the ground, green above and often purplish beneath, appearing in autumn. A slender stem then carries up to about a dozen dark maroon to purple-red flowers, each drawn out into long, thread-like tails on the sepals that give the plant its mayfly and mosquito names. The flowers open from late autumn through spring and are pollinated by small flies and fungus gnats. After flowering the plant sets dust-like seed and dies back to the dormant tuber over summer. It grows in moist, shaded forest and woodland on humus-rich or sandy soils and, like other terrestrial orchids, depends on specific soil fungi, which makes it hard to cultivate and unsuitable for transplanting. Plants need shade, leaf litter, and winter moisture while in growth, with a dry summer rest. Disturbance of the tuber or loss of the fungal partner usually leads to decline.
Native Range
Native to south-eastern Australia, occurring in Queensland, New South Wales, Victoria, Tasmania, and South Australia, where it grows in moist eucalypt forest and woodland, often under shrubs and in leaf litter on humus-rich or sandy soils.Suggested Uses
Grown mainly as a specimen in specialist terrestrial-orchid collections and pots rather than open garden beds. In its native range it features in bushland conservation interest. Displayed in shaded, leaf-littered settings where the small tailed flowers can be seen closely.How to Identify
Appearance
Size & Dimensions
Height4" - 1'
Width/Spread2" - 4"
Reaches mature size in approximately 2 years
Bloom Information
Detailed Descriptions
Flower Description
dark maroon to purple-redFoliage Description
green above, purplish beneathGrowing Conditions
Sun Requirements
Requires 2-5 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
This orchid relies on native soil fungi and leaf-litter conditions, which makes it hard to establish in gardens and unsuitable for transplanting from the bush. Where grown by specialists, it is kept in a shaded, free-draining humus-rich mix and given moisture through autumn, winter, and spring while in leaf and flower. Watering is reduced over summer for a dry tuber dormancy. Strong fertiliser is avoided, as the plant is adapted to lean, leaf-littered ground. Collecting plants or tubers from the wild is restricted and harms populations.Pruning
No pruning is needed. The leaf and flower stem wither naturally as the plant enters summer dormancy and can be cleared once dry. Seed capsules may be left to ripen if natural increase is wanted.Container Growing
✓ Suitable for container growing
Minimum container size: 1 gallons