About Microtis atrata Lindl.
Microtis atrata Lindl. is a terrestrial, perennial, deciduous herb that grows from an underground tuber. It produces a single erect, smooth, more or less solid leaf that measures 30–90 mm (1–4 in) long and about 3 mm (0.1 in) wide. Between two and forty or more yellowish-green flowers are densely arranged along a 10–40 mm (0.4–2 in) long flowering stem, bringing the whole plant to a total height of 50–120 mm (2–5 in). Plants growing in water can sometimes reach up to 200 mm (8 in) tall. The flowers measure about 2 mm (0.08 in) long and wide, making them the smallest flowers of any terrestrial Australian orchid; as the flowers age, they turn black. The dorsal sepal is egg-shaped to round, about 1 mm (0.04 in) long and wide, and forms a hood that covers the column. The lateral sepals are oblong, less than 1 mm (0.04 in) long, and spread apart from one another. The petals are egg-shaped and concave, while the labellum is oblong to egg-shaped. Flowering takes place from September to December, and is stimulated by fire the previous summer. This species, commonly known as the swamp mignonette orchid, is distributed in south-western Western Australia, south-eastern South Australia, southern Victoria, and northern Tasmania. It grows in swampy locations and winter-wet depressions, and sometimes grows in standing water. After summer fire, it can form colonies containing enormous numbers of plants.
