Rafflesia plants
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The Rafflesiaceae (Rafflesiaceae) are a family of plants within the order of the Malpighiales (Malpighiales). The three genera with around 20 species occur from southern China via Assam , Bhutan , Thailand to the western islands of the Malay Archipelago . The giant rafflesia ( Rafflesia arnoldii ) has the largest flowers of all flowering plants worldwide.
Description and ecology
These are root or shoot parasites without chlorophyll , with missing or reduced roots and leaves. These holoparasites parasitize species of the grapevine family (Vitaceae).
The radial symmetry flowers can be grouped in inflorescences or stand individually. In some species bracts are present in the vicinity of the flowers. The flowers have a diameter of 8 cm in Rhizanthes and up to over 1 meter in Rafflesia arnoldii . The overgrown bracts end with five lobes in Rafflesia , ten-lobed in Sapria and up to 16-lobed in Rhizanthes . Except for Rhizanthes , the flowers are unisexual. The plants of the other genera are monoecious ( monoecious ) or dioecious ( dioecious ) separate sexes. There are 12 to 40 stamens in the male flower . The female flowers are four to eight carpels an under constant ovary grown; the stamp is very short. The pollination is carried by flies.
From fertilization to maturity of blackish-brown berry it takes at Rafflesia six to eight months. The berries contain many small seeds. Real fine squirrels ( Callosciurus ) and species of real pointed squirrels ( Tupaia ) have been observed eating the berries of Rafflesia species and then spreading the seeds. Many animal species (e.g. Asian elephant and tapir ) are discussed as contributing epizoochorically to the spread.
Systematics
Since the plants have no organs apart from the flowers that allow a comparison, the systematic position of the small family of plants, the Rafflesiaceae, was previously unclear. New DNA analyzes have now shown that Rafflesia and its relatives are embedded in the base of the family tree of the previous milkweed family (Euphorbiaceae). In response to this, the separation of the Peraceae from the milkweed family was proposed, which has the consequence that the other milkweed family on the one hand remain monophyletic and on the other hand become more uniform with regard to the anatomy of the fruit and the seed coat. The relationships can be illustrated by the following cladogram:
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The research result is so surprising because, in clear contrast to the Rafflesia family, a tendency to shrink the flowers can be observed in the milkweed family, which in the genus Euphorbia reaches an extreme with tiny, individual bare stamens and individual bare ovaries.
In the Rafflesiaceae family there are three (to eight) genera with up to 27 species:
- Rafflesia R.Br. : The 14 to 20 species are common in Southeast Asia.
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Rhizanthes Dumort. : The two to four species thrive in tropical forests in South and Southeast Asia:
- Rhizanthes deceptor Bänziger & B.Hansen : Sumatra
- Rhizanthes infanticida Bänziger & B.Hansen : Thailand, Malaysia, Sumatra
- Rhizanthes lowii (Becc.) Harms
- Rhizanthes zippelii (flower) Spach : Java
- Sapria handle. : The three or so species are distributed from northeast India via Myanmar, Thailand, Cambodia and Vietnam to southeast Tibet and southern Yunnan .
swell
- The Rafflesiaceae family at DELTA. (Section description)
- Shumei Huang, Michael G. Gilbert: Rafflesiaceae. , P. 270 - online with the same text as the printed work , In: Wu Zhengyi, Peter H. Raven, Deyuan Hong (ed.): Flora of China. Volume 5: Ulmaceae through Basellaceae , Science Press and Missouri Botanical Garden Press, Beijing and St. Louis, 2003. ISBN 1-930723-27-X (section description)
- The Rafflesiaceae family at the Parasitic Plant Connection . (English)
- Lachezar A. Nikolov, Yannick M. Staedler, Sugumaran Manickam, Jürg Schönenberger, Peter K. Endress, Elena M. Kramer, Charles C. Davis: Floral structure and development in Rafflesiaceae with emphasis on their exceptional gynoecia. In: American Journal of Botany , Volume 101, Issue 2, February 2014, pp. 225–243. doi : 10.3732 / ajb.1400009
Individual evidence
- ↑ CC Davis, M. Latvis, DL Nickrent, KJ Wurdack, DA Baum: Floral gigantism in Rafflesiaceae. In: Science. Volume 315, number 5820, March 2007, p. 1812, doi : 10.1126 / science.1135260 , PMID 17218493 .
- ↑ The family peraceae in APWebsite (English)
- ^ The Rafflesiaceae family on the AP website.
Web links
- Rafflesiaceae on the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland.