Ximenia

Ximenia americana

Ximenia is a genus of shrubs and small trees, which is usually placed in the family of Olacaceae. The genus includes ten species and is pantropical spread.

• 8.1 Notes and references

Description

Vegetative characteristics

The Ximenia species are shrubs or small, not exceeding 12 m high trees. The branches are often spines at their ends or there are spikes in the leaf axils. The spirally arranged, petiolate leaves are often crowded together on short shoots. The simple and undivided, fiedernervigen, ganzrandigen leaf blades are up front trimmed blunt but usually have a short be translated Spitzchen. Stipules absent.

The wood of Ximenia americana is hard and quite heavy. The bulk density is 838-930 kg/m3 at 12 % moisture content. The heartwood is reddish - yellow, and rather sharply off against the lighter sapwood. The grain is straight to irregular, with a fine texture and a fairly high gloss. The wood may have a mild, pleasant odor.

Generative features

The inflorescences are in the leaf axils, often at the ends of short shoots. You can also sit on thorns, which are then converted to interpret as short shoots. It is up to 15 mm long stalked, wenigblütige, sometimes umbel -like cymes sessile or tufts, in some species, such as in horrida Ximenia and X. perrieri, even to individual flowers. Near the base of the flower stems are 2-4 bracteoles or they are missing.

The radial symmetry flowers are usually hermaphroditic, but functionally unisexual in several species. The small, broad cup-shaped calyx has (3 -) 4 (-5) teeth. He remains after the heyday, but increases little or no fruit to maturity. There are usually four, rarely five free, klappige in the bud, linealische to oblong petals present. These are bebärtet densely villous on the outside glabrous or pubescent and on the inside. Fully blossomed its front half is bent back. After flowering, the petals fall off. The stamens are fused together or with the petals. Most styles are available according to the number of petals eight or ten stamens present, each one half between stands before the sepals and petals in front of the other half. Ximenia horrida has only 4 (-5) stamens, which are arranged in front of the petals. The oblong- linealischen to almost egg-shaped anthers are basifix so attached at its base to the thread-like stamens. They have a thick connective and open lengthwise. In functionally female flowers no pollen is distributed. A discus is missing. The bottle-shaped ovary is upper constant and mostly vierfächerig almost to the top, rarely trilocular. The columnar pen is slim and has a small little head shaped scar. In functionally male flowers of the ovary is generally smaller and have a slightly different shape. In addition, the pen is sometimes very short or even missing. At the top of the central angle constant placenta in each ovary trade a single hanging, anatrope, bitegmische or different by the fusion degree unitegmische ovule. In functionally male flowers the ovules are missing.

The fruits are ovoid drupes with a relatively thin fleshy mesocarp and a crusty to woody endocarp. It develops in each fruit only a seed. This includes plenty of oily endosperm and a very small embryo.

Chromosomes

Regarding the number of chromosomes has only been Ximenia americana examined. For this type, two different figures were noted. It has therefore a diploid chromosome set of 2n = 24 and 2n = 26

Distribution and habitat

The distribution of the genus is pantropical, meaning they can be found in almost all tropical and subtropical regions. In the Americas, these plants grow between Baja California Sur, Florida and northern Argentina, in Africa extends the distribution area from Senegal and Sudan into northern regions of South Africa. In addition, the genus in tropical Asia and northeastern Australia occurs. In the Pacific there are deposits, for example in the Fiji Islands and the Tuamotu Archipelago. The largest area of ​​distribution has the pantropical species Ximenia americana, the colonized almost the entire area of the genus. Ximenia caffra occurs in eastern and southern Africa, the remaining eight species inhabit relatively small areas on the islands of Cuba, Hispaniola and Madagascar as well as in Mexico, Brazil and Paraguay.

The species of the genus occur within the tropics preferably in regions with dry forests and savannas.

Parasitism

Ximenia americana is an optional, non -host-specific semi parasite that can tap into the roots of other plants with haustoria to deprive them of water and nutrients. Also Autoparasitismus and the adhesion of haustoria on non-living objects are known.

Taxonomy and systematics

The genus was described in 1753 by Ximenia Swedish naturalist Carl Linnaeus in his work Species Plantarum. This took over here and even in his earlier work Hortus Cliffortianus an older genus name that the French botanist and monk Charles Plumier had influenced generations in his work Nova plantarum Americanarum. As Lektotypus 1920 Ximenia americana has been selected, the only previously described by Plumier and named as " Ximenia aculeata flore villoso, fructu luteo " Art as a second species of the genus Linnaeus also described Ximenia aegyptiaca, a kind of Balanites aegyptiaca in the day as a very different relationship is found. Heymassoli Aubl. , Pimecaria Raf., Rottboelia Scop. Ximeniopsis and Alain are synonyms of Ximenia.

The genus belongs to the tribe Ximenia Ximenieae that forms the subfamily Ximenioideae the Olacaceae family. Beside her are three genera of this tribe: Curupira, Douradoa and Malania.

Etymology

The genus is named in honor of the Spanish friar Francisco Ximénez, who in his four-volume work Quatro libros de la Naturaleza the first comprehensive natural history treatise published in 1615, which was relocated in America.

Species

The genus includes ten species.

Use

The wood of Ximenia americana is used for its pleasant smell and its color to a small extent as a substitute for sandalwood. But it rarely reaches dimensions which are sufficient for the production of furniture. The wood is easy to work and has a strong natural shine. The durability is quite high. The wood is also used for the production of charcoal.

The medical applicability of Articles Ximenia americana was examined among others by biologists of Ahamadu Bello University in Nigeria. It was confirmed that the bark extracts have a soothing effect on the nagana disease. An anti-cancer effect of ingredients of this plant was documented in 2005 in studies at the German Cancer Research Center Heidelberg in 17 tumor types in vivo and in vitro.

Swell

• Garcia J. G. 1963: 48th Olacaceae. In: Exell AW, Fernandes, A. & Wild H. (ed.): Flora Zambesiaca. Vol 2, part 1, Crown Agents for Oversea Governments and Administrations, London, pp. 328-336. - Ximenia - Online
• Sleumer H. O. 1984: Olacaceae. (Flora Neotropica Monographs 38). The New York Botanical Garden, New York, ISBN 0-89327-254 -X, 159 pp.
• Qiu Huaxing, Gilbert M. G. 2003: Olacaceae. In: Flora of China. Vol 5: Ulmaceae through Basellaceae. Science Press, Beijing, Missouri Botanical Garden Press, St. Louis, ISBN 1-930723 -27 X, pp. 200-204. - Ximenia - Online