Pterostylis grandiflora
cobra greenhood
Overview
Pterostylis grandiflora is a terrestrial, tuber-forming orchid of the family Orchidaceae, growing from an underground tuber and flowering in autumn and winter. Each flowering stem rises 4–12 inches (10–30 cm) tall and carries a single hooded flower 1–1.6 inches (25–40 mm) tall. The flower is translucent green with reddish-brown to dark markings over the curved hood, or galea, and has narrow, pointed lateral sepals that project forward. A rosette of stalked leaves forms at the base of non-flowering plants, while flowering stems bear stem-clasping leaves. After flowering the plant dies back to the tuber and rests through the dry summer. P. grandiflora grows in moist forest, woodland, and sheltered gullies in south-eastern Australia, often in leaf litter under shrubs. It depends on a moist, cool growing season and a summer dormancy, and declines where soils stay wet year-round or are disturbed. The green and brown flowers blend into the leaf litter and are easily overlooked.
Native Range
Native to south-eastern Australia, in moist forest, woodland, and sheltered gullies, often growing in leaf litter under shrubs in New South Wales and Victoria.Suggested Uses
Used in shaded pots, terrestrial orchid collections, and native woodland plantings. Suited to cool, sheltered positions with a dry summer rest. Grown in colonies that increase from offset tubers.How to Identify
Appearance
Size & Dimensions
Height4" - 1'
Width/Spread2" - 4"
Bloom Information
A single hooded flower opens on each stem in autumn and winter (April–August in the native range). The flower is translucent green with reddish-brown markings and 1–1.6 inches (25–40 mm) tall. Each plant flowers once per season before dying back to the tuber.
Detailed Descriptions
Flower Description
green with reddish-brown markingsFoliage Description
greenGrowing Conditions
Sun Requirements
Tolerates up to 3 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
Grow Pterostylis grandiflora in a cool, shaded position in a free-draining, humus-rich terrestrial orchid mix kept moist through autumn, winter, and spring. It needs a dry rest once the foliage dies back in summer. Summer watering rots the dormant tuber. The species increases by forming daughter tubers and can build into a colony over several seasons. It associates with soil fungi, so established plants are set back by disturbance and repotting. In cultivation it suits shaded pots and specialist terrestrial orchid collections.Pruning
No pruning is required. Spent flowering stems and withered leaves can be removed as the plant enters summer dormancy. The tuber regenerates growth the following autumn.Container Growing
✓ Suitable for container growing
Minimum container size: 1 gallons