Arachnitis

Arachnitis uniflora in the Maule Region, Chile

Arachnitis uniflora is the only species of the plant genus of the family of arachnoiditis Corsiaceae. Arachnitis uniflora is a mykoheterotrophe plant with an extensive distribution area, which extends from the north of South America to the Falkland Islands, but only in a few, disjoint, so widely separated areas, is widespread. Species and genus were first described in 1864, one in 1972 described another type is now usually regarded as synonymous.

Features

Arachnitis uniflora is an unbranched and erect, loose leaf green, herbaceous plant. Your rhizome and its roots ( the literature is ambiguous ) is star-shaped bulbous, ruddy, and is 10 to 15 centimeters below the ground. Each of the 4 to 17 individual roots is only 5 to 10 mm long and 3-4 mm wide. Lateral roots missing, rarely occurs foothills.

Arachnitis uniflora lives largely underground, only rarely trained flower stalk grows above ground. Only after complete formation of the root system sprouts of 6 to 40 inches long and up to 7 mm thick single standing stalk. He is of variable color, either whitish, yellowish or purple, sometimes colored only at the base and carries up to half the height of four to eight translucent, scaly at the base, at the top of stalk comprehensive sheets in alternating permanent arrangement. Perhaps the frail leaves are up to 5 inches long, 1 inch wide and five to seven annoying.

Because of its largely subterranean lifestyle is not known whether this is a once only or repeatedly flowering plant with her. In the latter case, the plants may not bloom every year. The flowers grow during flowering continuously and to a considerable extent on, however, the flower cups always stays shorter than wide. The flowers are fully retained to seed dispersal.

The odorless, zygomorphen and threefold individual flowers are terminal and almost upright, the ovary is inferior, short and spherical. The flowers are pale pink to flesh-colored in all parts. Five of the six petals (three tepals in two petal circles ) are linear - filiform, violet bent einnervig and light, they are up to 5 inches long and 2 to 2.5 millimeters wide.

The top sixth petal, the labellum is widened at the base, tapering to a point and thread-like ending. It is 4 to 5 inches long, on approach 13 to 17 millimeters wide, traversed 11-13 violet nerves and bent down towards the tip like a helmet on the base of the flower with the floral organs. The labellum is inside the left and right crossed the midrib of each dark red and tapering outwardly thickened longitudinal furrow and is rolled in its central part inward.

The flowers are hermaphrodite though, but show an extreme form of protandry by the anthers at the time of maturity cover the scars, then fall off and free up the then maturing scars. The six arranged in two circles, short and subulate shaped stamens are free, the anthers open slit longitudinally. The pollen is monocolpat, designed the tectum reticulate. The three pens are fused at the base and bent outwards, the scars are papillose, the papillae develop only from the dropping of the anther. As pollinators fungus gnats are suspected.

This fruit is inverted cone-shaped capsule fruits that stoop with maturity and open basis of three elongated columns at its front end. The numerous seeds are hawking span -shaped, 0.6 to 1 mm long and 0.06 to 0.2 millimeters wide. The seed coat consists of obround cells. Although the habitat is relatively calm, is sometimes assumed that the distribution of seeds by wind ( Anemochorie ), but it is also considered possible that the further flourishing during the seed dispersal plants continue to attract pollinators to spread the seeds.

Mykoheterotrophie

Arachnitis uniflora, like all types of Corsiaceae abandoned photosynthesis and accordingly forms no chlorophyll. Instead, she lives mykoheterotroph of mycorrhiza, the fungus genus Glomus. If the plant has stored enough nutrients in their root system and begins with the expulsion of the shoot axis, the mycorrhiza reduced gradually and the plant consumes instead their accumulated reserves. In the flowered plants, there are no more arbuscules.

Distribution and habitat

Arachnitis uniflora has an extremely disjoint distribution area, the 32 degrees of latitude stretching from the tropics to the sub-antarctic regions.

It is found in 2500-2800 m altitude in the central Andes in Bolivia, 150-1241 m in western Patagonia ( Argentina and Chile) and at a site at sea level on East Falkland. This for a species extremely wide spread is probably due to a reliktär and voreiszeitlich Another area of ​​distribution, which is then shrunk by climate changes after the ice age about 10,000 years ago to just two large rooms.

Your extreme spread according colonized macro climatically very different regions, but the same is always the particular microclimate always are sites in dense vegetation on rich, deep soils with high humidity during the growing season. In order to clearly separate wet and dry periods it is tolerant. It occurs scattered, but sociable.

Arachnitis uniflora is largely dependent on intact primary forests, but undisturbed retarded secondary vegetation can also be found in over time to resettle. Arachnitis uniflora is in the Patagonian forests associated with Chile cedar ( Austrocedrus chilensis ), coihue southern beech ( Nothofagus dombeyi ), blue-green southern beech ( Nothofagus glauca ), Osmorrhiza chilensis and barberries and Escallonia species, the Bolivian forests, especially of Erythrina falcata Yellow Trumpet flower ( Tecoma stans ), Piper elongatum, Cedrela lilloi, Luehea species, and species belonging to the families of the myrtle family ( Myrtaceae ) and the laurel family ( Lauraceae ) is formed.

On East Falkland, she finds herself on meadows and dunes eroded sandstone, but here are missing forests.

Botanical history and systematics

Were first described genus and species in 1864 were by Rudolph Amandus Philippi based on collections made his son in 1863. Much of these Collections were destroyed in a fire in the dwelling house of Philippi, the first description was then using some still the preserved specimens, but in poor condition and not subsequently obtained. So there existed no holotype, Collections of the following year 1864 have been proposed from the same location in 1996 as Neotyp. The genus name is a nomen conservandum against the orchid genus arachnites FW Schmidt from 1793, which is part of the Ragwurzen ( Ophrys ) today.

Originally Philippi was assumed that the plant to the orchid family (Orchidaceae) belonged, but later struck her own family Arachnitaceae ago, while other authors saw a relationship to the Burmanniaceae. The first description of Corsiaceae 1878 by ODOARDO Beccari arachnoiditis was then placed as a sister genus to the Corsia, the Corsiaceae were temporarily out as Untertaxon the Burmanniaceae, a position, but is regarded as no longer tenable since 1938.

Classification as a monotypic family Arachnitaceae was barely long advocate of new results, however, can be a possible spin-off from the Corsiaceae into an independent family appear to be justified. So already reported Traudel Rübsamen significant differences in morphological characteristics of the root, the gynoecium, fruit and especially the seeds. Molecular genetic studies supported this and are rooted Arachnitis near the Thismiaceae and Burmanniaceae in contrast to the rather well related with the Campynemataceae Corsia.

Up to the first description of arachnoiditis quetrihuensis by Milan Jorge Dimitri 1972, the genus was understood as monotypic. The species is now, however, usually synonymized because Arachnitis uniflora is considered to be so variable that it includes arachnoiditis quetrihuensis. This view was also supported by molecular genetic studies that could account for any difference between the two species.

Evidence

• Traudel Rübsamen: Morphological, embryological and systematic studies on Burmanniaceae and Corsiaceae ( with views of the Orchidaceae - Apostasioideae ), Berlin, 1986, ISBN 3-443-64004-4
• Pierre L. Ibisch, Christoph Neinhuis, Patricia Rojas N.: On the Biology, Biogeography, and Taxonomy of arachnoiditis Phil nom. cons. ( Corsiaceae ) in Respect to a New Record from Bolivia. In: Willdenowia, 1996, Volume 26, Issue 1/ 2, pp. 321-332.
• Laura S. Domínguez, Alicia Sersic: The southernmost myco - heterotrophic plant, arachnoiditis uniflora: root morphology and anatomy. In: Mycologia, 2004, Volume 96, Issue 5, pp. 1143-1151 ( Online)
• Paula J. Rudall, Alison Eastman: The questionable affinities of Corsia ( Corsiaceae ): evidence from floral anatomy and pollen morphology. In: Botanical Journal of the Linnean Society, 2002, Volume 138, pp. 315-324.