Filiform sundew
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Filiform sundew ( Drosera filiformis ) |
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| Drosera filiformis | ||||||||||||
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The thread-like sundew ( Drosera filiformis ) is a species of sundew ( Drosera ) in the family of the sundew plants (Droseraceae). This carnivorous plant occurs only in two varieties on the east coast of North America.
description
Vegetative characteristics
The thread-like sundew is an upright, perennial herbaceous plant .
The plant forms about 5 to 30 long, thread-like, 15 to 40 centimeters high catch leaves , which are covered with the typical tentacles almost from the ground surface, which are provided with large drops of glue and can move towards the prey. Towards the end of the vegetation period, Drosera filiformis retreats into a hibernation bud, with the help of which it can survive longer frosts.
Generative characteristics
The inflorescences , which can be up to 60 centimeters high, are wraps . From April the 4 to 21 flowers bloom one after the other. The hermaphroditic, self-pollinating flowers are radial symmetry and five-fold with a double flower envelope . The five pink petals are unusually large at 7 to 17 millimeters.
The number of chromosomes is 2n = 20.
Occurrence
Drosera filiformis is found disjoint on the east coast of North America. It grows on sandy, moist to wet soils. D. filiformis occurs in the USA in New Jersey , Maryland , North Carolina but also Florida . The latter occurrence was described as D. filiformis var. Floridana . In Canada, the plant only grows in the province of Nova Scotia . Drosera filiformis var. Tracyi grows exclusively on the US Gulf Coast, mainly in Florida, but also in Georgia , Alabama and Mississippi .
Systematics
The first description of Drosera filiformis was in 1808 by Samuel Rafinesque .
From Drosera filiformis There are three varieties:
- Drosera filiformis Raf. var. filiformis
- Drosera filiformis var. Floridana B.Rice : smaller, deep red to orange leaves, thinner flower stems and smaller flowers
- Drosera tracyi or Drosera filiformis var. Tracyi (Macfarl.) Diels .
D. tracyi differs significantly from the other forms. The following table shows the differences taking into account the statistically most likely 68% of the values:
| property | Drosera filiformis | Drosera tracyi |
|---|---|---|
| Color of the tentacles | red to dark red | White |
| Blade length | 9.7-17 cm | 26-32 cm |
| Petiole length | 0-9 mm | 22-44 mm |
| Inflorescence height | 8.9-19 cm | 31-45 cm |
| Number of flowers | 7-15 | 13-19 |
| Ratio of tentacle length / leaf width | 2.6-4.8 | 0.9-2.3 |
| Leaf / petiole ratio | 18-110 | 5.1-25 |
Because of the geographical isolation and the morphological differences, many authors see Drosera filiformis var. Tracyi as a separate species: Drosera tracyi. This classification is controversial and both versions are often used.
The cross D. filiformis × D. tracyi is named Drosera × californica Hort. ex Cheek (1993), D. filiformis var. floridana × D. tracyi has been described as Drosera × californica var. arenaria B. Rice . The hybrid occurs naturally only in Florida, the only place where both species grow together. The name is based on a widespread cultivar of this hybrid which was created in 1973 and is called 'California Sunset'. The cross is fertile, which speaks against the classification as two separate species, since almost all hybrids between different species in this section are sterile.
D. filiformis var. Filiformis forms the natural hybrid Drosera × hybrida Macfarl with the middle sundew . which is sterile.
swell
- Barry A. Rice: The thread-leaf sundews Drosera filiformis and Drosera tracyi, published in: Carnivorous Plant Newsletter Volume 40, 2011
- Excerpt from 'Drosera of North America' by Barry Rice, Alastair Robinson and Andreas Fleischmann (2017)
literature
- Ludwig Diels : Droseraceae (= The Plant Kingdom . 26 = 4, 112, ZDB -ID 846151-x ). Engelmann, Leipzig 1906.
- Wilhelm Barthlott , Stefan Porembski, Rüdiger Seine, Inge Theisen: Carnivores. Biology and culture of carnivorous plants. Eugen Ulmer GmbH & Co., Stuttgart 2004, ISBN 3-8001-4144-2 .
Individual evidence
- ^ Drosera filiformis at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ↑ ICPS - CPN Vol. 10 (1981): New Cultivar Registrations. Retrieved September 4, 2018 .
