Roridula
Roridula | |
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Roridula dentata | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Asterids |
Order: | Ericales |
Family: | Roridulaceae Engl. & Gilg (1924) nom.cons. |
Genus: | Roridula L. (1764)
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Species | |
Roridula distribution |
Roridula (
Description
Both species are diploids having six sets of homologue chromosomes (2n=12).[1]
Differences between the species
R. dentata can be distinguished by its larger habit of up to 2 m, the line-shaped lobes along its leaves and the umbel-like inflorescences, whereas R. gorgonias is smaller, up to 1⅓ m, has entire leaves and spike-like inflorescences.[7][8]
Taxonomy
Carl Linnaeus described Roridula in 1764.[1] The name Roridula derives from roridus, a Latin word meaning “dewy”, which refers to the fine drops of liquid on the tentacles that give the leaves a dewy appearance.[4]
Over time, different botanists have held different views on the affinities of the genus Roridula.
core Ericales |
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Distribution, habitat and ecology
The seeds of Roridula dentata germinate shortly after a fire has destroyed the vegetation. Flowering mostly occurs in September and December.[3]
Like many other carnivorous plants, Roridula has a rather poorly developed root system, and grows on acidic and leached soils in humid locations. Roridula shares its habitat with several
Roridula does not respond by bending tentacles to struggling insects, unlike Drosera, that secrete a sticky mixture of saccharides or proteins. Instead, it carries three types of glandular hairs that differ in size: long, medium, and short. The long tentacles are less sticky, and by struggling, the insect comes in contact with the much more sticky medium and short glands, which completely immobilize it.[12]
Carnivorous plants like Drosera secrete enzymes that break down proteins (so-called proteases) from the captured insects, and so make available nitrates to these plants, that grow in soils with low ammonium and nitrate content. R. gorgonias however lacks proteases and is thus unable to extract these nutrients from trapped prey directly. Instead, each plant houses individuals of the bug Pameridea roridulae, which quickly close in on the trapped insects and feed on them. The bugs consequently defecate on the leaves. In a nitrogen-15 tracing experiment, where prey insects enriched with the rare heavy nitrogen isotope were eaten by Pameridea bugs, the share of N15 increased, showing that the plant had taken up nitrogen nutrients from the captured insects.[13]
R. dentata also has a hemipteran resident, Pameridea marlothi, and may receive nitrogen nutrients in much the same way. In addition, several crab spider species of the genus Synema can be found on the plant and these may both prey on the captive insects as well as on the resident bugs. The unrelated Australian genus Byblis resembles Roridula in having sticky tentacles, which do not secrete digestive enzymes and also lives together with hemipteran bugs in much the same way.[13]
Pameridea is assigned to the Miridae, a family of bugs that further live from sucking plant juices. Although Pameridea depends on insects with their high protein content that have been captured by Roridula for completing its life cycle, it can survive on plant juices. In case of a fire, the bugs probably evacuate their home plant and fly off. Even if they do not find another Roridula specimen, the bugs can sit out the period until Roridula plants have germinated and sufficiently grown, by sucking juices of other plant species.[15]
Fossil record
Fragments of fossil leaves, morphologically very close to
The pieces of amber with the roridulid remains were found in a
Use
Early settlers in parts of the Cape used to hang Roridula branches from the ceiling to catch flies.[15]
References
- ^ a b c d e f Conran, J.G. (2013). "Roridulaceae". In Klaus Kubitzki (ed.). Flowering Plants. Dicotyledons: Celastrales, Oxalidales, Rosales, Cornales, Ericales; Volume 6 of The Families and Genera of Vascular Plants. Springer Science & Business Media. p. 340.
- ^ "Roridula: the vliegebos". Sarracenia.com.
- ^ a b c "Roridula dentata". SANBI PlantZAfrica.
- ^ a b c "Roridula gorgonias". SANBI PlantZAfrica.
- ^ "Fly bush (Roridula dentata)". SANBI Red List of South African Plants.
- ^ "Fly bush (Roridula gorgonias)". SANBI Red List of South African Plants.
- ^ "Compilation - Roridula gorgonias". JSTOR Global Plants.
- ^ "Compilation - Roridula dentata". JSTOR Global Plants.
- doi:10.12705/646.6.
- S2CID 2332644.
- PMID 25657836.
- PMID 19749112.
- ^ a b Ellis, Allan G. (1994). Indirect carnivory in Roridula gorgonias (Roridulaceae); a carnivorous plant dependent on hemipterans for prey nutrient uptake (PDF). p. 37.
- PMID 18689418.
- ^ ISBN 978-0191085390.
- ^ PMID 25453067.
External links
- Photos of Roridula gorgonias on iNaturalist
- Photos of Roridula dentata on iNaturalist