Drosera indica
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Drosera indica on location (Australia) |
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Drosera indica is a carnivorous plant belonging to the genus sundew ( Drosera ). It is one of the most widespread species of the genus and native to numerous countries in the ancient tropics and subtropics .
Drosera indica is largely insignificant for humans as a useful plant. From a systematic point of view, however, it raises a number of questions, as it has diverse and sometimes unique morphological peculiarities as well as a high degree of variability in characteristics, especially in its emergence . This is why the term Drosera indica complex is sometimes used .
description
Drosera indica is an unbranched, annual plant with few, fibrous roots and reaches a height of 5 to 50 (rarely 2 to 70) centimeters. Younger plants stand upright, older ones grow lying down, whereby the active end of the stem axis always remains upright. The plant can be yellowish-green to deep red in color. Their number of chromosomes is 2n = 28.
leaves
The linear, 1 to 10 centimeter long and 0.4 to 3 millimeter wide leaves are loosely distributed alternately on the thin, flexible stem , covered with short glandular hairs . The leaf blades become a little narrower towards the (if present) 0.1 to 1.5 cm long petiole , this can be hairless, hairy or glandular-hairy. Young leaves stand upright, with increasing age they tilt, old leaves hang down withered. Stipules are absent or are reduced to small hairs. At the outermost point, the leaf blades are elongated, pointed, at their edges they are densely covered with 1 to 6 millimeter long tentacles that carry knob-shaped glands.
In addition to the glandular hairs at could Drosera indica also emergences nichtdrüsige be observed, as previously only hartmeyerorum Drosera were known. Their exact function is still unclear; they may be used to attract prey. The emergences observed in Drosera indica are between 0.1 and 1.0 millimeters in size. Australian varieties are mushroom-shaped and have a hemispherical yellow head, while African varieties have a colorless, translucent, wavy, plate-shaped head.
blossoms
The flowering period extends from the beginning of spring to the beginning of autumn. The one to four, mostly completely covered with glandular hairs, inflorescence axes reach a length of up to 15 centimeters and grow diagonally to the side from the shoot out of the leaf axils. The 2 to 5 centimeters long, with up to 0.1 millimeter long hairs, gradually balding inflorescence is a screw and bears between three and thirty flowers on 3 to 20 millimeter long pedicels , which lengthen up to 20 millimeters as the fruit ripens . The linear bracts reach a length of 6 to 8 millimeters and lie close to the flower stem, the bracts are narrow linear and 0.5 to 2 millimeters long.
The five lanceolate to narrowly elongated, pointed sepals are 3 to 5 millimeters long and 1 to 2 millimeters wide. They are covered with up to 0.03 millimeter long trichomes and red-headed, 0.1 millimeter long glandular hairs and grown together at the base. The five petals are 5 to 10 millimeters long and 3 to 6 millimeters wide, inversely lanceolate to inversely ovate. The color spectrum is diverse, the spectrum ranges from white to orange and light red to pink and purple, on the outside they are often pale in color. The 5 papillary stamens are 1,2 to 5 millimeters, the yellow, filamentary to arrowhead-shaped dust bag 3 to 4 (often 0.5 to 0.8) mm long. The hairless ovary is obovate to approximately round, and 1 to 2 (to 5) mm long. The three styluses are divided into two parts and twisted almost down to the base, the papillary scar forming the end piece is 2 to 3 millimeters long.
Fruits and seeds
The broadly elongated to inverted egg-shaped, 2 millimeter wide and 4 to 6 millimeter long seed pods have three chambers. The seeds, which are 0.4 to 0.6 millimeters long and around 0.3 (to 0.5) millimeters thick, are black, egg-shaped to elliptical and taper to a point at one end; the seed coat is ribbed lengthways and crosswise in a coarse network. The average seed weight is 0.0155 grams per thousand air-dry seeds.
Distribution and habitat
The species is widespread and common in tropical and subtropical regions of the Paleotropic .
It is found in Africa from the extreme west of Africa ( Senegal , Gambia ) through Niger and Central Africa ( DR Congo ) to the north of southern Africa ( Angola , Zimbabwe , South Africa , Mozambique ) and Madagascar . In East and Southeast Asia they range from China and Japan through India , the Philippines and Indonesia to New Guinea . In Australia it is only absent in the extreme south.
It thrives at altitudes of up to 1500 meters in wet, acidic locations such as swamps, banks and moors, often on rocky ground. It can occur more frequently in disturbed locations.
Systematics and botanical history
Drosera indica was first described by Carl von Linné in 1753 using a specimen from Ceylon and given the incorrect epithet indica (= from India). The species is one of the exceptional cases in which the holotype is not a herbarium but an illustration. Although some varieties and forms have been described, none of them are currently recognized.
Regardless of this, due to the extremely diverse morphology of the species, it is often referred to as a “ Drosera indica complex” which has not yet been systematically processed and which presumably contains other taxa. In 2001 Jan Schlauer classified Drosera hartmeyerorum as a separate species and Susandarini et al. identified three morphologically different groups for Australia in 2002 and suggested them as cryptic species , which, however, require further investigation before a description:
| Group A | Group B | Group C | |
|---|---|---|---|
| Seed surface | Numerous small depressions | Reticulate | Furrowed |
| leaves | Stalked | Blunt | Stalked, red-streaked abaxially |
| Stamens | Filiform to triangular | Thread-like | "Cobra-like" |
| blossom | - | - | White with red anthers |
Within the genus, Drosera indica is relatively isolated in the section Arachnopus , the only representative of which it was until Drosera hartmeyerorum was described.
Lowrie divided the complex into 11 different types in 2013.
use
Drosera indica is largely insignificant for humans as a useful plant. It is occasionally cultivated by lovers. In Asian countries, like other sundew species, it is collected in large quantities as a medicinal plant and exported to European countries, among others. Since the collections are not sustainable, Drosera indica is sometimes threatened locally by over-collection, for example in Andhra Pradesh, India .
proof
- Ludwig Diels: Droseraceae. In: A. Engler (Ed.): Pflanzenreich 4. 112: 109, 1906, pp. 77-79.
- Lianli Lu, Katsuhiko Kondo: Droseraceae. In: Flora of China. Volume 8, 2001, p. 200 ( online ).
- Barry J. Conn: Droseraceae. In: Barry J. Conn (Ed.): Handbooks to the Flora of Papua New Guinea. Volume 3, 1995, ISBN 0-522-84582-7 , p. 52.
- JR Laundon: Droseraceae. In: Flora Zambesiaca. Volume 4, 1978 ( online ).
- JR Laundon: Droseraceae. In: Flora of Tropical East Africa. Volume 5, 1959.
- AA Obermeyer: Droseraceae. In: The Flora of Southern Africa. Volume 13, 1970.
- Allen Lowrie: Carnivorous Plants of Australia. Volume 3, 1998, pp. 180-183.
- GJ Harden: Drosera indica. In: New South Wales Flora. ( Online ).
- Grazyna Paczkowska: Drosera indica. In: Florabase - The Western Australian Flora. 1996 ( online ).
Individual evidence
Most of the information in this article has been taken from the sources given under references; the following sources are also cited:
- ↑ HT Clifford: Dicotyledon seedling morphology as a correlate of seed size. In: Proceedings of the Royal Society of Queensland. 109, 2000 pp. 39-48 (quoted from Flynn, S .; Turner, RM; Stuppy, WH: Seed Information Database (release 7.0, Oct. 2006) ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. ).
- ↑ Carl von Linné: Species plantarum. 1. No. 282, 1753.
- ↑ Rick Walker: Carnivorous Plant Database , Online , accessed February 15, 2007
- ↑ Ratna Susandarini, John G. Conran, Graham G. Collins, Allen Lowrie: Morphological variation within the Drosera indica (Droseraceae) complex in northern Australia. In: Australian Journal of Botany. 50, pp. 207-214.
- ↑ The Drosera indica Species Complex | ICPS. Retrieved October 3, 2018 .
- ↑ K. Jayaram, MNV Prasad: Drosera indica L. and D. burmanii Vahl., Medicinally important insectivorous plants in Andhra Pradesh - regional threats and conservation. In: Current Science. 91, No. 7, 2006, pp. 943-946.
Web links
- Drosera indica . In: U. Brunken, M. Schmidt, S. Dressler, T. Janssen, A. Thiombiano, G. Zizka: West African plants - A Photo Guide. Senckenberg Research Institute, Frankfurt am Main 2008.
