Heliamphora
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 Heliamphora distribution
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The genus Heliamphora (pronounced /hiːliːæmfɔːɹə/ or /hɛliːæmfɔːɹə/, from Greek: helos = marsh, amphoreus = amphora) contains 16 species of pitcher plants endemic to South America. The species are collectively known as sun pitchers, based on the mistaken notion that the heli of Heliamphora is from the Greek helios, meaning "sun". In fact, the name derives from helos, meaning marsh, and so they are correctly referred to as marsh pitcher plants. Species in the genus Heliamphora are carnivorous plants that consist of a modified leaf form that is fused into a tubular shape. They have evolved mechanisms to avoid completely filling up with water and attract, trap, and kill insects. At least one species (H. tatei) produces its own proteolytic enzymes that allows it to digest its prey without the help of symbiotic bacteria.
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[edit] Morphology
All Heliamphora are herbaceous perennial plants that grow from a subterranean rhizome. H. tatei grows as a shrub, up to four meters tall, all other species form prostrate rosettes. The leaf size ranges from a few centimeters (H. minor, H. pulchella) up to more than a meter (H. ionasii). Heliamphora possess tubular traps formed by rolled leaves with fused edges. Marsh pitcher plants are unusual among pitcher plants in that they lack lids (opercula), instead having a small "nectar spoon" on the upper posterior portion of the leaf. This spoon-like structure secretes a nectar-like substance, which serves as a lure for insects and small animals. Each pitcher also exhibits a small slit in its side that allows excess rainwater to drain away, similar to the overflow on a sink. This allows the marsh pitcher plants to maintain a constant maximum level of rainwater within the pitcher. The pitchers' inner surface is covered with downward-pointing hairs to force insects into the pitchers' lower parts.
[edit] Carnivory
Though often counted among the various carnivorous plants, Heliamphora do not produce their own digestive enzymes (i.e. proteases, ribonucleases, phosphatases, etc.), relying instead on the enzymes of symbiotic bacteria to break down their prey. They do, however, attract prey through special visual and chemical signals and trap and kill the prey through a typical pitfall trap. Field studies of H. nutans, H. heterodoxa, H. minor, and H. ionasii have determined that none of these species produce their own proteolytic enzymes. If production of these enzymes was used as a strict demarcation of what is and what is not a carnivorous plant, many of the Heliamphora species would not meet the requirement. H. tatei is one of the few species observed to produce both digestive enzymes and wax scales, which also aid in prey capture. The pattern of carnivory among Heliamphora species, combined with habitat data, indicates that carnivory in this genus evolved in nutrient-poor locations as a means to improve absorption of available nutrients. Most Heliamphora typically capture ants, while H. tatei's improvements on the design allow it to capture and absorb nutrients from more flying insects. The carnivorous habit among these species is lost in low light conditions, which suggests that certain nutrient concentrations (specifically nitrogen and phosphorus) are only limiting during periods of fast growth under normal light conditions, thus rendering most of the carnivorous adaptations inefficient and not energy cost effective.[1]
[edit] Distribution
All Heliamphora species are endemic to the Tepuis of the Guiana Highlands in the tripoint Venezuela, Guyana and Brazil, except H. heterodoxa and H. sarracenioides, which also occur in the Gran Sabana. Many of the Tepuis have not yet been explored for Heliamphora, and the large number of species described in recent years suggests that many more species may be awaiting discovery.
[edit] Botanical history
The first species of the genus to be described was H. nutans, which George Bentham named in 1840 based on a specimen collected by Robert Hermann Schomburgk. This remained the only known species until Henry Allan Gleason described H. tatei and H. tyleri in 1931, also adding H. minor in 1939. Between 1978 to 1984 Julian Alfred Steyermark and Bassett Maguire revised the genus (to which Steyermark had added H. heterodoxa in 1951) and described two more species, H. ionasii and H. neblinae, as well as many infraspecific taxa. Various exploratory expeditions as well as review of existing herbarium specimens has yielded many new species in recent years, mainly through the work of a group of German horticulturalists and botanists (Thomas Carow, Peter Harbarth, Joachim Nerz and Andreas Wistuba).[2]
[edit] Care in cultivation
Heliamphora are regarded by carnivorous plant enthusiasts and experts as one of the more difficult plants to maintain in cultivation. They require cool (the "highland" species) to warm (the "lowland" species) temperatures with a constant and very high humidity.[3] The highland species, which originate from high in the cloudy Tepui mountaintops, include H. nutans, H.ionasii, and H. tatei. The lowland Heliamphora, such as H. minor and H. heterodoxa have migrated to the warmer grasslands at the foot of the Tepuis.
Shredded, long-fibered or live sphagnum moss is preferred as a soil substrate, often with added horticultural lava rock, perlite, and pumice. The substrate must always be kept moist and extremely well-drained. Misting Heliamphora with purified water is often beneficial to maintain high humidity levels.
Propagation through division only has a limited rate of success, as many plants that are divided go into shock and eventually die. Germination of Heliamphora seed is achieved by scattering it on milled sphagnum moss and keeping in bright light and humid conditions. Seed germination begins after many weeks.
[edit] Classification
The genus Heliamphora contains the most species in the Sarraceniaceae family and is joined by the Cobra Lily and the North American pitcher plants in that taxon.
- Heliamphora chimantensis
- Heliamphora elongata
- Heliamphora exappendiculata
- Heliamphora folliculata
- Heliamphora glabra
- Heliamphora heterodoxa
- Heliamphora hispida
- Heliamphora ionasii
- Heliamphora minor
- Heliamphora neblinae
- Heliamphora nutans
- Heliamphora pulchella
- Heliamphora sarracenioides
- Heliamphora tatei
[edit] Natural hybrids
At least five natural hybrids have been recorded.[4]
- H. chimantensis × H. pulchella
- H. elongata × H. ionasii
- H. exappendiculata × H. glabra
- H. glabra × H. nutans
- H. hispida hybrids involving H. tatei and possibly another undescribed species
[edit] References
- ^ Jaffe, K., Michelangeli, F., Gonzalez, J.M., Miras, B., and Ruiz, M.C. (1992). Carnivory in Pitcher Plants of the Genus Heliamphora (Sarraceniaceae). New Phytologist, 122(4): 733-744. (First page available online: JSTOR PDF of first page and HTML text of abstract
- ^ Informationen on dates and authors of descriptions
- ^ Rice, Barry A. (2006). Growing Carnivorous Plants. Timber Press: Portland, Oregon. ISBN 0-88192-907-0
- ^ McPherson, S. 2007. Pitcher Plants of the Americas. The McDonald & Woodward Publishing Company, Blacksburg, Virginia.
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