|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