Thelymitra megacalyptra
plains sun orchid
Southeastern Australia (Victoria, New South Wales, South Australia)
Overview
Thelymitra megacalyptra is a terrestrial, tuberous sun orchid of southeastern Australia that grows each year from an underground tuber. A single fleshy, channelled leaf emerges in autumn or winter, followed in spring by an upright flower stem 8-20 inches (20-50 cm) tall carrying several flowers. The flowers are blue to mauve, sometimes with darker spots, about 0.8-1.2 inch (2-3 cm) across, and unlike many orchids they have a simple, near-symmetrical shape with the column hooded by a large structure. Sun orchids open their flowers only in warm, sunny conditions and stay closed on cool or overcast days, so plants can be passed unnoticed in dull weather. After flowering, the plant sets seed and dies back to the tuber for the dry summer. It grows in grassland, open woodland, and mallee on well-drained soils. Like other terrestrial orchids, it relies on symbiotic soil fungi and specific insects, which makes it difficult to grow outside specialist collections. Several plains-dwelling populations have declined with the loss of native grassland.
Native Range
Thelymitra megacalyptra is native to southeastern Australia, occurring in Victoria, New South Wales, and South Australia. It grows in native grassland, grassy woodland, and mallee on well-drained sandy and loamy soils.Suggested Uses
Grown mainly in specialist terrestrial-orchid collections and native grassland conservation projects, not in general garden beds. Its dependence on soil fungi and a strict wet-winter, dry-summer cycle make routine cultivation difficult. In the wild it is part of the ground flora of grassland and open woodland.How to Identify
Appearance
Size & Dimensions
Height8" - 1'8"
Width/Spread2" - 4"
Bloom Information
Flowering occurs in spring, mainly October and November in its native range, and only on warm, sunny days. Several blue to mauve flowers open in succession on each stem. The plant then sets seed and dies back to its tuber for the dry summer.
Detailed Descriptions
Flower Description
blue to mauveFoliage Description
greenGrowing Conditions
Sun Requirements
Requires 6-10 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
Thelymitra megacalyptra is a terrestrial orchid that grows from a tuber in well-drained sandy or loamy soil in full sun. It needs a moist, cool growing season through autumn, winter, and spring, then a warm, dry summer dormancy. Like other sun orchids, it depends on symbiotic soil fungi, so it does not transplant or divide like ordinary garden perennials. Specialist growers raise it in deep pots of native soil mix with carefully timed watering. It is rarely grown in general gardens and is most often seen in the wild or in dedicated orchid collections.Pruning
No pruning is required. The single leaf and flower stem die back naturally to the tuber after seed sets. The dormant tuber is left undisturbed through the dry summer.Container Growing
✓ Suitable for container growing
Minimum container size: 1 gallons