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Dendrosicyos

Dendrosicyos

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Dendrosicyos is a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

 genus in the Cucurbitaceae
Cucurbitaceae
The plant family Cucurbitaceae consists of various squashes, melons, and gourds, including crops such as cucumber, pumpkins, luffas, and watermelons...

. The only species is Dendrosicyos socotranus, the cucumber tree. The species is endemic to the island of Socotra
Socotra
Socotra , also spelt Soqotra, is a small archipelago of four islands in the Indian Ocean. The largest island, also called Socotra, is about 95% of the landmass of the archipelago. It lies some east of the Horn of Africa and south of the Arabian Peninsula. The island is very isolated and through...

 in Yemen
Yemen
The Republic of Yemen , commonly known as Yemen , is a country located in the Middle East, occupying the southwestern to southern end of the Arabian Peninsula. It is bordered by Saudi Arabia to the north, the Red Sea to the west, and Oman to the east....

, and is the only species in the Cucurbitaceae to grow in a tree form.

Features


It has a bulbous trunk and a small crown. It was first described by Isaac Bayley Balfour
Isaac Bayley Balfour
Sir Isaac Bayley Balfour FRS FRSE was a Scottish botanist. He was the son of John Hutton Balfour who was also a botanist.-Biography:...

 in 1882. 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.

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.
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
Parenchyma
Parenchyma is a term used to describe a bulk of a substance. It is used in different ways in animals and in plants.The term is New Latin, f. Greek παρέγχυμα - parenkhuma, "visceral flesh", f. παρεγχεῖν - parenkhein, "to pour in" f. para-, "beside" + en-, "in" + khein, "to pour"...

. In it are embedded in small xylem
Xylem
Xylem is one of the two types of transport tissue in vascular plants. . The word xylem is derived from the Classical Greek word ξυλον , meaning "wood"; the best-known xylem tissue is wood, though it is found throughout the plant...

 strands that are linked to each other (anastomosis
Anastomosis
An anastomosis is the reconnection of two streams that previously branched out, such as blood vessels or leaf veins. The term is used in medicine, biology, mycology and geology....

). This Xylem strands have a cambium
Cambium (botany)
A cambium , in botany, is a tissue layer that provide undifferentiated cells for plant growth. It forms parallel rows of cells, which result in secondary tissues....

, the secondary phloem
Phloem
In vascular plants, phloem is the living tissue that carries organic nutrients , in particular, glucose, a sugar, to all parts of the plant where needed. In trees, the phloem is the innermost layer of the bark, hence the name, derived from the Greek word "bark"...

 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 flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

s 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
Cucurbitacin
Cucurbitacin is any of a class of biochemical compounds that some plants — notably members of the family Cucurbitaceae, that includes the common pumpkins and gourds — developed in order to defend themselves from herbivores...

 with an unusual ring formation.

Proliferation and locations


Described in 1882 by Isaac Bayley Balfour
Isaac Bayley Balfour
Sir Isaac Bayley Balfour FRS FRSE was a Scottish botanist. He was the son of John Hutton Balfour who was also a botanist.-Biography:...

, 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
Djibouti
Djibouti , officially the Republic of Djibouti , is a country in the Horn of Africa. It is bordered by Eritrea in the north, Ethiopia in the west and south, and Somalia in the southeast. The remainder of the border is formed by the Red Sea and the Gulf of Aden at the east...

. It is quite abundant on the dry parts of the island of Socotra
Socotra
Socotra , also spelt Soqotra, is a small archipelago of four islands in the Indian Ocean. The largest island, also called Socotra, is about 95% of the landmass of the archipelago. It lies some east of the Horn of Africa and south of the Arabian Peninsula. The island is very isolated and through...

, 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
Samhah
Samhah is an inhabited island of the Socotra archipelago, between the main island of Socotra, and Somalia. Like the whole group, it belongs to Yemen, specifically to Hadhramaut Governorate. Somalia also claims this Island. It measures 40 km² in area, making it the smallest of the three...

.
Dendrosicyos socotranus is only on the island of Socotra
Socotra
Socotra , also spelt Soqotra, is a small archipelago of four islands in the Indian Ocean. The largest island, also called Socotra, is about 95% of the landmass of the archipelago. It lies some east of the Horn of Africa and south of the Arabian Peninsula. The island is very isolated and through...

, an island off the front of Horn of Africa
Horn of Africa
The Horn of Africa is a peninsula in East Africa that juts hundreds of kilometers into the Arabian Sea and lies along the southern side of the Gulf of Aden. It is the easternmost projection of the African continent...

. 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
Tribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...

 made Coniandreae. Dendrosicyos is the basal tribe within the tribe, their sister group, are all other genera of the tribe

The name Dendrosicyos socotranus means cucumber tree of Socotra.