Acianthus amplexicaulis

The genus Acianthus from the orchid family (Orchidaceae ) consists of 21 species. They are small, herbaceous plants, their distribution is limited to eastern Australia, New Zealand and New Caledonia.


The Acianthus species possess as a Überdauerungsorgan grow underground tuber that is annually replaced by a new, resulting in a short rhizome. In addition, another daughter tubers may develop on the root-like spurs that serve the vegetative propagation. Roots are not present. From the tuber of the shoot axis rises with only one sheet. The petiole is adherent to the stem axis, the blade is deployed horizontally directly above the ground. The leaf blade is quite wide and short, rarely up to twice as long as wide.

The shoot axis is located above the foliage leaf continued as a racemose inflorescence. The flowers are small, stalked, 'upside and not dyed striking. The petals are not fused together. Sepals which are formed three identical according to the type or the top is substantially wider than the lateral. The petals are of equal size or smaller than the outer petals. The lip is adherent to the base for a short distance to the column. The lip is not lobed, it ends pointed. On the lip sits a more or less large callus at the base, two glands sitting, some species produce nectar. The column is slender and curved. She wears at the top of the two -chambered stamen with four pollinia. These all depend on a common viscid disc ( Viscidium ) or two on an adhesive wafer. The capsule fruit contains numerous winged seeds.

Many species are pollinated by small flies from the families Anisopodidae, Sciaridae and Mycetophilidae that are attracted by nectar.


The species of the genus Acianthus are in eastern Australia, distributed in Tasmania, New Caledonia, the North and South Islands of New Zealand, on Stewart Island, the Chatham Islands and the Kermadecinseln. They usually occur in shady, wooded areas that have at least during the growth period, no dryness. They colonize altitudes up to 1100 meters.

Systematics and botanical history

The genus Acianthus is classified within the family of orchids in the subtribe Acianthinae. It was erected in 1810 by Robert Brown. He described three species are similar in their column without lateral widening, the number of pollinia and their pointed sepals. The name comes from the Greek words ἀκίς akis, "top", and ἄνθος anthos, " flower", together and refers to this sharp -ended petals.

The following species are known in the genus Acianthus:

  • Acianthus aegeridantennatus N.Hallé
  • Acianthus amplexicaulis ( F.M.Bailey ) Rolfe
  • Acianthus atepalus Rchb.f.
  • Acianthus bracteatus Rendle
  • Acianthus caudate R.Br.
  • Acianthus confusus Guillaumin
  • Acianthus corniculatus Rendle
  • Acianthus cymbalariifolius F.Muell. & Kraenzl.
  • Acianthus elegans Rchb.f.
  • Acianthus exsertus R.Br. - ( Type species )
  • Acianthus fornicatus R.Br.
  • Acianthus grandiflorus Schltr.
  • Acianthus halleanus Cyrus
  • Acianthus heptadactylus Kraenzl.
  • Acianthus ledwardii Rupp
  • Acianthus macroglossus Schltr.
  • Acianthus oxyglossus Schltr.
  • Acianthus sinclairii Hook.f.
  • Acianthus tenuilabris Schltr.
  • Acianthus veillonis N.Hallé
  • Acianthus viridis Hook.f.