Dendrosicyos socotranus
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Dendrosicyos socotranus |
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Dendrosicyos socotranus is a member of the cucurbit family (Cucurbitaceae). The species is the only representative of the genus Dendrosicyos . It occurs only on the island of Socotra and grows tree-shaped.
features
Dendrosicyos socotranus is one of the very few species of the cucurbit family that grows tree-shaped. It is up to 7 m high and has a bottle-shaped trunk made of soft wood ( pachycaulie ). The trunk reaches a diameter of up to one meter. Numerous branches and small twigs also grow out of the trunk, a difference to other representatives of the bottle tree. The main stem grows sympodially : the tip of the shoot tilts until it is no longer the highest point of the plant; from the now highest point a new shoot arises, which takes over the top growth. This process repeats itself over and over again.
The trunk consists largely of parenchyma . Embedded in it are small xylem strands that are interconnected ( anastomose ). These xylem strands have a cambium that forms a secondary phloem . There is not one continuously active cambium, a new cambium is formed one after the other at the periphery (successive cambium). Dendrosicyos is the first representative of the cucurbit family in which such a follow-up eristem was proven.
The leaves are about 10 cm long and wide, their leaf margin is somewhat thorny. On the underside of the leaf there are hairs made up of two to seven cells, with the two cells at the top often containing cystolites . The epidermal cells are lignified , the surface has a thick layer of cutin.
The flowers are in arm- flowered inflorescences in the leaf axils. The species is monözisch , so forms male and female flowers on one plant. The flowers are yellowish-orange with long corolla lobes . The fruits are egg-shaped and spring up when ripe. The seeds are around 6 mm in size.
The plant contains Dendrosycin, an iso cucurbitacin with unusual ring formation.
Distribution and locations
Dendrosicyos socotranus occurs only on the island of Socotra , an island off the Horn of Africa . It grows here in the bush forest. Due to the anatomical features of the trunk (lots of parenchyma) and leaves, the species is well adapted to dry locations.
Systematics
The genus is placed within the cucurbits in the subfamily Cucurbitoideae and here in the tribe Coniandreae. Dendrosicyos is the most basic clan within the tribe, its sister group are all other genera of the tribe.
Species and genus were first described by Isaac Bayley Balfour in 1882 . The name Dendrosicyos socotranus means cucumber tree from Socotra .
literature
- ME Olson: Stem and leaf anatomy of the arborescent Cucurbitaceae Dendrosicyos socotrana with comments on the evolution of pachycauls from lianas . Plant Systematics and Evolution, Volume 239, 2003, pp. 199-214 doi : 10.1007 / s00606-003-0006-1
Web links
Individual evidence
- ↑ California State University, Fullerton page , accessed May 4, 2008.
- ^ HA Hussein, OB Abdel-Halim, SM Marwan, AA El-Gamal, R. Mosana: Dendrocyin: an isocucurbitacin with novel cyclic side chain from Dendrosicyos socotrana. Phytochemistry, Vol. 65, 2004, pp. 2551-2556. doi : 10.1016 / j.phytochem.2004.07.016
- ↑ Alexander Kocyan, Li-Bing Zhang, Hanno Schaefer, Susanne S. Renner: A multi-locus chloroplast phylogeny for the Cucurbitaceae and its implications for character evolution and classification . Molecular Phylogenetics and Evolution, Volume 44, August 2007, pp. 553-577. doi : 10.1016 / j.ympev.2006.12.022 , (PDF; 381 kB)