Key to Tasmanian Dicots
Hydrorchis (=Microtis orbicularis; Orchidaceae) 4a:60    
Swamp Onion Orchids (Hydrorchis orbicularis) is an uncommon species that grows in swampy places near the north coast.

This species has a single, erect narrow leaf held high on the flowering stalk (scape). The scape is erect and unbranched and bears several to many shortly stalked flowers. The flowers are small and quite inconspicuous, with sepals and petals less than 2 mm long. The flowers are inverted (with the labellum above the centre of the flower, and facing downwards).

This species is very similar to Microtis species and Microtidium atrata, and differs from the former in lacking the dark swellings on the labellum, and from the latter in having a rounded labellum. It also differs in colour - Microtis and Microtidium are typically distinctly yellow-green, whereas Hydrorchis is green or reddish.


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