T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Gastrodia longcolumn (Potato orchid)

Kingdom: Plantae
(unranked): Angiosperms
(unranked): Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Epidendroideae
Tribe: Gastrodieae
Subtribe: Gastrodiinae
Genus: Gastrodia
Species: G. longcolumn
Binominal name: Gastrodia longcolumn
Common name: Potato orchid 

Gastrodia longcolumn is a leafless saprophytic orchid, one of New Zealand’s five native orchids in the genus: Gastrodia. They are commonly called Potato Orchids. The other New Zealand species are Gastrodia minor, Gastrodia cunninghamii, Gastrodia sesamoides, Gastrodia longcolumn "black" (a black form)

Gastrodia longcolumn has an erect, dark/light brown, leafless stem that grows up to 1 metre tall and can have a diameter up to 10 mm. The stem grows from a thick tuber.
The 60 odd 1.5cm olive green/dark brown flowers that appear during December and January are bell-shaped. The sepals and petals are joined together forming a tube (perianth). This is covered in small, light coloured, wart-like projections. The white 1cm long labellum has a yellow tip. The column is visible and is of a similar length to the labellum. The fruit is an oval-shaped capsule growing to about 15 mm long. Plants growing in dark shade often have darker flowers than those growing in well-lit locations.
Gastrodia longcolumn grows in the lowland to montane areas of New Zealand, from Lat 37S in the North Island south to Stewart Island.

Notice the labellum yellow tip

Thanks to Wikipedia for text and information: