Dendrosicyos

Dendrosicyos
Dendrosicyos
An 1890s photograph by Henry Ogg Forbes
Conservation status
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Cucurbitales
Family: Cucurbitaceae
Subfamily: Cucurbitoideae
Tribe: Melothrieae
Subtribe: Dendrosicyinae
Genus: Dendrosicyos
Balf.f.
Species: D. socotranus
Binomial name
Dendrosicyos socotranus
Balf.f.

Dendrosicyos is a monotypic genus in the Cucurbitaceae. The only species is Dendrosicyos socotranus, the cucumber tree. The species is endemic to the island of Socotra in Yemen, and is the only species in the Cucurbitaceae to grow in a tree form.

Contents

Features

It has a bulbous trunk and a small crown.[1] It was first described by Isaac Bayley Balfour in 1882.[2] A recent molecular phylogenetic analysis of the family Cucurbitaceae found that the Dendrosicyos lineage is about twice as old as the island, and thus seems to be an island relict of a progenitor lineage that went extinct on the mainland.[3]

It measures up to 6 m high, and 2 m in diameter. The leaves are nearly round, covered with fine bristles, and slightly toothed. The yellow flowers (3 cm), males and females are present on the same plant for cross pollination. It reproduces only by seed. Fruits (3 x 5 cm) are green, turning red when ripe brick.

Seedlings subjected to overgrazing and regeneration may be compromised over time, except for seedlings protected by Cissus subaphylla to prevent the goats graze. The species is considered vulnerable. In Soqotri, his name is qamhiyn.

Contrary to what would suggest its region of origin, Dendrosicyos socotrana responds well to a drench and fertilizer, if the temperature is greater than 20º C. Individuals in habitat can attain 10 feet/3 m in height. The plants grew relatively fast, but didn't get taller than a meter. Trunks were succulent, but not bottle-shaped when young. The plant produced flowers at five years from seed. [4]

Dendrosicyos socotranus will grow to 7 m and has a bottle-shaped base made of soft wood (Pachycaulie). The trunk reaches a diameter of up to one meter. Numerous small twigs and branches grow from the stem, one difference from other representatives is the bottle tree growth form. The main stem grows sympodial tends to shoot tip, until it is no longer the highest point of the plant, now the highest point rises a new shoot, which takes over the top growth. This process is repeated again and again.

The base consists largely of parenchyma. In it are embedded in small xylem strands that are linked to each other (anastomosis). This Xylem strands have a cambium, the secondary phloem forms. There is not a consistently active cambium, it will always continue sequentially formed on the periphery of a new cambium (cambium successively). Dendrosicyos is the first member of the Cucurbitaceae, in which such meristem has been demonstrated.

The leaves are about 10 inches long and wide, its leaf edge is a little thorny. On the underside of leaves sit trichome from two to seven cells, the cells often contain two cystoliths. The epidermal cells are lignified, the surface carries a thick cells however secrete.

The flowers are in inflorescences in the leaf axils. The species is monoecious is, therefore, male and female flowers on one plant. The flowers are yellowish-orange with long Petal (corolla lobes). The fruit are ovate and jump on to maturity. The seeds are about 6 mm .

The plant contains Dendrosycin, an Iso cucurbitacin with an unusual ring formation. [5]

Proliferation and locations

Described in 1882 by Isaac Bayley Balfour, the species is generally described as endemic to the island of Socotra, although some sources (1887) mentioned that she was present on the African continent in Djibouti. It is quite abundant on the dry parts of the island of Socotra, associated with Croton socotranus in the plains, and on calcareous soils to 500 m elevation. There are also isolated specimens on the close island of Samhah. Dendrosicyos socotranus is only on the island of Socotra, an island off the front of Horn of Africa. It grows here in the bush. By the anatomic characteristics of stem (much parenchyma) and leaves. The species is well adapted to dry sites.

Nomenclature

The genus is in the pumpkin plants in the subfamily Cucurbitoideae and here in the Tribe made Coniandreae. Dendrosicyos is the basal tribe within the tribe, their sister group, are all other genera of the tribe [6]

The name Dendrosicyos socotranus means cucumber tree of Socotra.

References

  1. ^ Kingdon, Jonathan (1989). Island Africa: The Evolution of Africa's Rare Plants and Animals. Princeton, New Jersey: Princeton University Press. pp. 40–41. ISBN 0-691-08560-9. 
  2. ^ Miller, A. (2004). Dendrosicyos socotrana. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 19 November 2009.
  3. ^ Schaefer, H.; Heibl, C; Renner, S (2009). "Gourds afloat: a dated phylogeny reveals an Asian origin of the gourd family (Cucurbitaceae) and numerous oversea dispersal events". Proceedings of the Royal Society B 276 (1658): 843–851. doi:10.1098/rspb.2008.1447. PMC 2664369. PMID 19033142. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2664369. 
  4. ^ http://biology.fullerton.edu/facilities/greenhouse/stories_out_of_school/dendrosicyos.html
  5. ^ HA Hussein, O.B. Abdel-Halim, S.M. Marwan, A.A. El-Gamal, R. Mosana:Dendrocyin: to isocucurbitacin with novel cyclic side chain from Dendrosicyos socotranaPhytochemistry, Volume 65, 2004, p. 2551-2556..[volume & issue needed]
  6. ^ Kocyan Alexander, 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.[volume & issue needed] [~ http://www.umsl.edu/ renners/Kocyan_Cucurbits_MPE2007.pdf (PDF)]
  • M. E. Olson: Stem and leaf anatomy of the arborescent Cucurbitaceae Dendrosicyos socotrana with comments on the evolution of pachycauls from lianas. Plant Systematics and Evolution, Band 239, 2003, S. 199–214 doi:10.1007/s00606-003-0006-1


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