Rhizanthella
Rhizanthella is a genus of the orchid family. The three known species of the genus are native to Australia and live entirely underground as the only orchids.
Features
All species of the genus are leaf and rootless, underground plants. They have completely abandoned photosynthesis and form accordingly no chlorophyll, instead they live myco -heterotrophic. As so-called mykoheterotrophe plant itself Rhizanthella gardneri nourished thereby of arbuscular mycorrhizal fungi, which in turn live in a symbiosis with the surrounding plants.
The 5 to 15 mm thick and 3 to 15 cm long rhizome of the plant is weakly branched, white and fleshy. Periodically grows from the rhizome until just below the surface a so-called capitulum, an upright flower head with a diameter of 15 to 25 millimeters, which is surrounded by fleshy bracts, the tips occasionally break through the earth's surface. The 8-90 short, tubular florets are spirally arranged at the top flattened capitulum and reddish brown, reddish or dark violet color. As pollinators probably serve small flies.
Even after flowering, the stems are not renewed and the seeds ripen underground. The distribution of seeds thought to be by marsupials that eat the fleshy seed pods and the seeds excrete the feces.
Occurrence / Botanical History
In 1928, the first plant of the genus Rhizanthella were discovered near the western Australian city of Perth. It was Rhizanthella gardneri, which was up to 1960 found at seven other locations in Western Australia.
In 1931, then became Wales Queensland found in a Eucalyptuswald the second species of this genus in the border region of New South. It was described by Herman Montague Rucker Rupp in 1932 as Crypthanthemis slateri and assigned in 1984 as Rhizanthella slateri the genus Rhizanthella.
2006, was described in Lamington National Park collected specimens, the third species of the genus on the basis of two in 1958, Rhizanthella omissa.
Due to their rarity, all species are ( at risk =) as Vulnerable classified.
System
- Rhizanthella gardneri R. S. Rogers - type species
- Rhizanthella omissa D.L.Jones & M.A.Clem.
- Rhizanthella slateri ( Rupp ) M.A.Clem. & P.J.Cribb
Evidence
- David L. Jones: A complete guide to native orchids of Australia: including the Iceland territories, Frenchs Forest, 2006, ISBN 1-8770-6912-4. .
- R. Bad: the orchids. 4 Bd & Regist. Revised. K. Senghas. Blackwell Wiss. -Verl., Berlin / Vienna 2003 (3rd ed.) ISBN 3-8263-3410-8.