Diuris sulphurea R.Br.

Taxonomic Identity and Growth Form

Diuris sulphurea R.Br. is a tuberous perennial herb.

Leaf Characteristics

It grows up to three linear to lance-shaped leaves, each 200 to 500 millimetres (8 to 20 inches) long and 3 to 4 millimetres (0.1 to 0.2 inches) wide.

Flowering Stem and Inflorescence

Up to seven flowers, each 20 to 30 millimetres (0.8 to 1 inch) wide, are borne on a flowering stem 200 to 500 millimetres (8 to 20 inches) tall.

Flower Coloration

The flowers are bright yellow with a few prominent dark brown markings.

Dorsal Sepal Morphology

The dorsal sepal is egg-shaped, erect or leaning forward, 15 to 20 millimetres (0.6 to 0.8 inches) long and 9 to 13 millimetres (0.4 to 0.5 inches) wide.

Lateral Sepal Morphology

The lateral sepals are green or green and brown, linear, 16 to 25 millimetres (0.6 to 1 inch) long, 1 to 3 millimetres (0.04 to 0.1 inches) wide, turned downwards and usually parallel to each other.

Petal Morphology

The petals are erect or turned backwards, with an egg-shaped blade 12 to 18 millimetres (0.5 to 0.7 inches) long and 7 to 11 millimetres (0.3 to 0.4 inches) wide, growing on a dark brown stalk 5 to 8 millimetres (0.2 to 0.3 inches) long.

Labellum Structure

The labellum is 10 to 15 millimetres (0.4 to 0.6 inches) long and has three lobes. The centre lobe is spade-shaped, 8 to 13 millimetres (0.3 to 0.5 inches) long and 7 to 10 millimetres (0.3 to 0.4 inches) wide. The side lobes are egg-shaped with the narrower end towards the base, 4 to 6 millimetres (0.16 to 0.24 inches) long and 2.5 to 4 millimetres (0.1 to 0.2 inches) wide.

Labellum Callus

A ridge-shaped callus runs along the mid-line of the labellum base, extending about halfway along the labellum.

Flowering Period

Flowering occurs from August to December.

Common Name and Distribution

Common name tiger orchid, this species occurs in all Australian states except Western Australia and the Northern Territory.

Habitat

It grows in forest, woodland, heath, grassland and coastal scrub.

Associated Species and Hybridization

In Victoria, it often grows alongside Diuris pardina and sometimes forms hybrids with this species.