Pitcher plants
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White pitcher plant ( Sarracenia leucophylla ) in its natural habitat |
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The pitcher plants ( Sarracenia ), also trumpet plants or trumpet leaf , are a genus of carnivorous plants from the family of pitcher plants (Sarraceniaceae) consisting of eight species . They are found almost exclusively in the east and southeast of the United States . All species of the genus have been strongly pushed back by human influence, many are endangered, some even threatened with extinction. The genus was named after Michel Sarrazin .
description
All eight species are perennial, herbaceous plants , the leaves of which arise in rosettes from a short rhizome or trunk.
leaves
The leaves are erect, with the exception of those of the red pitcher plant and the parrot pitcher plant . They are tubular and have a wing-shaped long side as well as a so-called operculum, a (immobile) hood-shaped leaf process at the upper end of the tube. The opening of the tube is bordered by the peristome , a lip that is rolled outwards and which, like the operculum and the wing-shaped long side, is covered with nectaries .
By means of this leaf structure, all pitcher plants catch prey without the use of any moving parts, so the traps are passive. A combination of color, scent and secretion of the nectaries serves to attract the prey, which at least in the yellow pitcher plant ( Sarracenia flava ) also contains coniin , which has a numbing effect on insects.
The catch itself happens through an abrupt fall of the prey from the peristome into the interior of the tube. The hoses of the parrot pitcher plant are an exception to this safety device . They lie flat on the ground and function as a trap in their partially flooded locations .
Zones
Each leaf consists of three to five different zones, depending on the species: Zone 1 is the hood, Zone 2 is the peristome and the entrance area, Zones 3 and 4 (which are combined in some species) and (only in the case of the red pitcher plant ) Zone 5 are deeper-lying sections of the actual hose. Each of these zones has a special function for which it is equipped differently.
- Zone 1: The hood . In most species, it at least partially covers the opening of the tube and thus prevents the tubes from overflowing and thus preventing the prey from being washed out by rain. But it also guides prey to the hose through directed hair. In some species ( small pitcher plant , parrot pitcher plant ) it is bent relatively tightly over the tube opening and provided with clusters of chlorophyll-free spots that allow outside light to pass through almost unhindered and act like windows ( areolae ), a feature that is even more pronounced in the closely related cobra lily . Prey animals that have already been caught try to fly out of the trap through these windows and fall into the hose when attempting to escape.
- Zone 2: Peristome and upper tube area . This zone is essentially formed by the peristome, which excretes particularly large amounts of nectar and thus lures the prey from the appendage into the actual tube. This zone also includes the upper hose area, in which the directed hair of the hood continues.
- Zone 3: Middle hose area . This zone is completely smooth and no longer has any hairs, here the prey suddenly lose their grip and fall into the digestive fluid. The surface of this area is densely populated with digestive glands that release digestive enzymes into the tube fluid.
- Zone 4: Lower hose area . This section of the tube is used to absorb the dissolved nutrients and is in turn provided with downwardly directed hair, which prevents prey animals from climbing out of the digestive fluid.
- Zone 5 : This zone is only found in the red pitcher plant, it is hairless, free of glands and is not used for absorption, as has long been assumed. Their function is still unknown.
blossoms
Flowers are formed in early spring, at the same time as or just before the first leaves are formed. They stand nodding individually on long flower stalks high above the tubes so as not to endanger possible pollinators. Depending on the species, the flowers have a diameter of three to ten centimeters and an unusual appearance. The flower is surrounded by three bracts and consists of five sepals , five petals , numerous stamens and a star-shaped, umbrella-like stylus that catches falling pollen and ends with the stigma at the tips of the star. This structure also prevents self-pollination. The petals lap over the inside of the flower, the petals and sepals are either red or yellow, depending on the species.
The main pollinators are bees, which squeeze themselves inside the flower in search of nectar , where they pick up pollen from both the anthers and the bottom of the style. You can only leave the flower through the indentations of the stylus. This will prevent them from touching the stigma and self-pollinating the plant.
The flowers of all species often smell strongly, occasionally unpleasant, for example the yellow pitcher plant smells strongly of cat urine, but other species also smell of violets . The flowers stay open for around two weeks after opening.
Fruit and seeds
In the case of pollination, the petals are shed and the five- chamber ovary swells to a capsule fruit , with considerably fewer seeds being produced in one chamber than in the other four. Each capsule produces between three and six hundred seeds that mature over a period of around five months, then the capsule wilts and ruptures, releasing the seeds. These are 1.5 to 2 millimeters long and have a rough, waxy shell that allows them to be swept away by the water.
Pitcher plants are cold germers , the seeds require a previous cold period to germinate. Right from the start they form functional traps, which, however, are still of a simpler structure in young plants. It takes around three to five years for the plants to mature.
distribution
Distribution area
All species in the genus are native to the southeastern and eastern parts of the United States , particularly in coastal areas. The distribution area of the red pitcher plant ( Sarracenia purpurea ) extends north to Canada and there also inland far to the west of the continent. A few subspecies or varieties ( Sarracenia rubra ssp. Alabamensis , Sarracenia rubra ssp. Jonesii or Sarracenia purpurea var. Montana ) can be found further inland in mountains such as the Appalachians .
Habitats
The typical habitat is moderately warm, all pitcher plants, as perennials, depend on clearly different summer and winter. They colonize permanently moist, often oozing-wet locations such as moors, swamps and wet meadows with acidic, sandy and nutrient-poor soils, whereby pitcher plants, unlike many other carnivores , are relatively tolerant of the presence of nutrients in the soil, but are then exposed to increasing competitive pressure from other plants . They prefer full sun, unshaded locations.
Anointed occurrences
In several cases pitcher plants, mostly the red pitcher plant ( Sarracenia purpurea ), were anointed by plant lovers in suitable locations outside their natural range . Some of these locations are naturalized, the oldest known in the Swiss Jura is around a hundred years old. In Europe there are anointed locations in Ireland, the English Lake District and Sweden . There are anointings even within North America, such as on the coast of Mendocino County, California . In Germany there are anointings of this kind, for example in Middle Franconia , in the Münsterland , in the Lausitz and in the Bavarian Forest , which have been stable for several years.
Endangerment and Status
Pitcher plants are an endangered genus. It is estimated that around 98% of their original habitats in the southeastern United States have already been destroyed. The main threat factors at present are: the expansion of urban settlement areas, the draining of habitats for forestry purposes, the infiltration of herbicides from neighboring agricultural areas, the suppression of natural fires that clear the competing vegetation, and the cutting of hoses for floristic purposes (here The hoses are dried after cutting and used in dried flower arrangements, for this purpose around 1.6 million hoses were cut in 1991 according to the US Fish and Wildlife Service ), whereby the increasing compaction of the soils through frequent repeated walking and driving of the habitats is also reflected here has a negative effect on the moisture balance of the habitats and the growth of the plants. In the case of rare and hardly available species, collection by collectors also played a certain role (see below).
Although legal protection exists in the states of Florida , Georgia , and South Carolina , since such laws have no effect on privately owned land and the majority of the holdings of the corresponding states are located on such land, they are in fact unprotected. In the states of Alabama and Mississippi , which could be called the heart of the range, pitcher plants have no legal status at all, so they are not protected on either private or public land. According to the USA Endangered Species Act , the green pitcher plant ( Sarracenia oreophila ) and two subspecies of the brown-red pitcher plant , namely Sarracenia rubra subsp. alabamensis and Sarracenia rubra subsp. jonesii , endangered as Federally ("endangered nationwide"). These three taxa are also listed in Appendix 1 of the Washington Convention on the Protection of Species (CITES), so the trade in these species (if they come directly from wild stocks) is illegal. All other species are listed in Appendix 2 and enjoy little protection from the federal government.
Some plant communities have started programs for the conservation of individual species or the genus as a whole. In 2003, for example, the International Carnivorous Plant Society (ICPS) launched a program that allowed plants of the endangered subspecies Sarracenia rubra subsp. alabamensis sells at cost price, on the one hand to take the pressure off the plants and on the other hand to establish a gene pool of the plants in culture. Furthermore, conferences were organized for the exchange between experts dealing with the protection of plants, and a project to renaturalize a habitat of the rare Sarracenia purpurea var. Montana was initiated.
In 2004, the North American Sarracenia Conservancy (NASC) was founded with the aim of “recording the taxonomic, morphological and genetic diversity of the genus Sarracenia for the purpose of preservation and culture”. She is currently building a genebank that is supposed to provide an overview of all existing genetic variants that are currently in culture so that they can be reintroduced into the wild at suitable locations if necessary. A similar institution, albeit run by an individual, is the collection of British pitcher plant expert Mike King, which represents over 650 different gene strands of all taxa of the genus. The collection is part of the UK NCCPG National Plant Collection .
Even if hardly any of the initiatives contribute to the preservation of the habitats themselves or can reduce the threats to which the stocks are subject, they at least preserve the species in culture, represent a reservoir for possible renaturation in the future and reduce at least one, albeit one only occasionally significant threat, namely that of collection.
Systematics
The genus closest to the pitcher plants is the Darlingtonia with its only species, the cobra lily . Together with the somewhat further related sump jugs ( Heliamphora ) the two genera constitute the family of Pitcher plants . The phylogeny of the genus itself is still unclear.
Eight species are currently generally recognized; species rank is occasionally discussed for the five subspecies of the brown-red pitcher plant. The description of a variety of the red pitcher plant, Sarracenia purpurea subsp. venosa var. burkii as an independent species Sarracenia rosea 1999 was widely disputed .
The following species are recognized:
- Pale pitcher plant ( Sarracenia alata (Alph. Wood) Alph. Wood )
- Yellow pitcher plant ( Sarracenia flava L. )
- White pitcher plant ( Sarracenia leucophylla Raf. )
- Small pitcher plant ( Sarracenia minor Walter )
- Green pitcher plant ( Sarracenia oreophila wherry )
- Parrot pitcher plant ( Sarracenia psittacina Michx. )
- Red pitcher plant ( Sarracenia purpurea L. )
- Brown-red pitcher plant ( Sarracenia rubra Walter )
(Information on subspecies, varieties and forms in the respective articles)
Since pitcher plants will readily hybridize with one another, their hybrids are fertile and the species areas sometimes overlap, there are numerous intermediate forms in nature . In the past, these were always the reason for the description of new, but dubious taxa.
Botanical history
Due to the early settlement of the area of distribution of the genus, its (then) wide distribution and its striking appearance, pitcher plants were first mentioned and depicted as Thuris limpidi folio by Matthias de L'Obel in his "Stirpium Adversaria Nova" in 1576 . In 1601, Clusius described a red pitcher plant as Limonium peregrinum in his "Rariorum plantarum historia" , so incorrectly saw it as a sea lavender species. The genus bears its current scientific name after the French doctor and naturalist Michel Sarrazin (1659–1734), who is considered the father of Canadian botany. At the end of the 17th century he sent living specimens of the red pitcher plant to the Parisian botanist Joseph Pitton de Tournefort , who in 1700 described them as Sarracena Canadensis . Carl von Linné took over the generic name slightly changed in his "Species Plantarum" (1753). At that time, two species were known (in addition to the red, the yellow pitcher plant ). The first flowering in culture came in 1773; In 1793, William Bartram, in his book about his travels in the southwestern United States, mentioned that there were numerous insects in the hoses of plants, but doubted that they would get any benefit from it. In 1887, the amateur botanist Joseph H. Mellichamp succeeded in proving the carnivory of the genus suspected by Charles Darwin in 1875; detailed chemical studies by J. S. Hepburn, E. Q. St. John and F. M. Jones from 1920 and 1927 further substantiated this. Extensive site observations as well as laboratory studies by Edgar Wherry increased knowledge of the genre, as did the work of Donald Schnell and Edward Case in the present.
use
Pitcher plants have firmly established themselves in the ornamental plant market over the last twenty years, in particular the robust and hardy red pitcher plant is regularly represented in carnivore assortments, including from DIY stores and supermarkets. In addition to her, there are also often indeterminate hybrids. As already mentioned above under endangerment and status, the hoses are also harvested in the USA for cut flower arrangements.
literature
- Wilhelm Barthlott , Stefan Porembski, Rüdiger Seine, Inge Theisen: Carnivores. Biology and culture of carnivorous plants. Ulmer, Stuttgart 2004, ISBN 3-8001-4144-2 .
- Donald E. Schnell: Carnivorous Plants of the United States and Canada. 2nd edition. Timber Press, Portland OR 2002, ISBN 0-88192-540-3 .
Web links
- Pitcher plant generic description on FleischfressendePflanzen.de
- Sarracenia species
- North American Sarracenia Conservancy (English)
Large parts of the article are taken from the English Wikipedia article Sarracenia in the version of June 1, 2006.
Individual evidence
- ^ Aaron Ellison, Lubomír Adamec (Ed.): Carnivorous Plants: Physiology, Ecology, and Evolution . Oxford University Press, 2017, pp. 292 .
