''Aextoxicon'' is a genus of

dioecious Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is ...

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

s native to southern Chile and Argentina. It is the only genus in the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

family Aextoxicaceae, and is itself represented by the olivillo (''Aextoxicon punctatum''). It is a large

evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...

tree native to the forests of the

Valdivian temperate rain forests The Valdivian temperate forests (NT0404) is an terrestrial ecoregion, ecoregion on the west coast of southern South America, in Chile and Argentina. It is part of the Neotropical realm. The forests are named after the city of Valdivia, Chile, Val ...

and

Magellanic subpolar forests The Magellanic subpolar forests () are a terrestrial ecoregion of southernmost South America, covering parts of southern Chile and Argentina, and are part of the Neotropical realm. It is a temperate broadleaf and mixed forests ecoregion, and ...

of the Pacific coast of southern Chile, where it forms is a

canopy Canopy may refer to: Plants * Canopy (biology), aboveground portion of plant community or crop (including forests) * Canopy (grape), aboveground portion of grapes Religion and ceremonies * Baldachin or canopy of state, typically placed over an a ...

tree in the

broadleaf forest A forest is an ecosystem characterized by a dense community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological functio ...

s. It can reach 15 m tall. The

APG system The APG system (Angiosperm Phylogeny Group system) of plant classification is the first version of a modern, mostly molecular-based, system of plant taxonomy. Published in 1998 by the Angiosperm Phylogeny Group, it was replaced by the improved ...

(1998) and the

APG II system The APG II system (Angiosperm Phylogeny Group II system) of plant classification is the second, now obsolete, version of a modern, mostly Molecular phylogenetics, molecular-based, list of systems of plant taxonomy, system of plant taxonomy that ...

(2003) left the family Aextoxicaceae unplaced in the

core eudicots The eudicots or eudicotyledons are flowering plants that have two seed leaves (cotyledons) upon germination. The term derives from ''dicotyledon'' (etymologically, ''eu'' = true; ''di'' = two; ''cotyledon'' = seed leaf). Historically, authors h ...

. It has since been included in the order

Berberidopsidales Berberidopsidales is an order of Southern Hemisphere woody flowering plants. The name is newly accepted in the APG III system of plant taxonomy. APG II system, of 2003, mentions the possibility of recognizing the order, as comprising the familie ...

. The genus was formerly often included in the family

Euphorbiaceae Euphorbiaceae (), the spurge family, is a large family of flowering plants. In English, they are also commonly called euphorbias, which is also the name of Euphorbia, the type genus of the family. Most spurges, such as ''Euphorbia paralias'', ar ...

Description

''Aextoxicon punctatum'' is a large tree often found in the

or emergent. It has opposite leaves with dark green coloration on the top and lighter green below, and is covered in rusty peltate scales. The flowers are

actinomorphic Floral symmetry describes whether, and how, a flower, in particular its perianth, can be divided into two or more identical or mirror-image parts. Uncommonly, flowers may have no axis of symmetry at all, typically because their parts are spirall ...

and unisexual, in hanging

racemes A raceme () or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the shoo ...

. The flowers have 5

sepals A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

and 5

petals Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''coroll ...

. Male flowers have 5

stamens The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filamen ...

opposite the sepals while female flowers have two

carpels Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ...

that fuse to form a bilocular ovary. The

fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...

is a single seeded

drupe In botany, a drupe (or stone fruit) is a type of fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pip'' (UK), ''pit'' (US), ''stone'', or ''pyrena'') of hardened endocarp with a seed ...

that resembles an olive, thus giving the plant its common name. File:Aextoxicon punctatum, flor masculina - Flickr - Pato Novoa.jpg, Male flower File:Aextoxicon punctatum flor femenina - Flickr - Pato Novoa.jpg, Female flower File:Aextoxicon punctatum (53136865463).jpg, Leaves

Distribution and habitat

''Aextoxicon punctatum'' is found in Chile, usually in damp places from the Bosque de Fray Jorge National Park southwards to the

Chiloé Archipelago The Chiloé Archipelago (, , ) is a group of islands lying off the coast of Chile, in the Los Lagos Region. It is separated from mainland Chile by the Chacao Channel in the north, the Sea of Chiloé in the east and the Gulf of Corcovado in the s ...

, also in the Valdivian forest and Magellanic forests of the southern Pacific coast. In Argentina it is present in the middle reaches of the Rio Negro valley, being invasive on the island of

Choele Choel Choele Choel is the capital of the department of Avellaneda in the Argentine province of Río Negro, and the most important settlement within the ''Valle Medio'' ("Middle Valley") agricultural area of the Río Negro River in Patagonia. Overvie ...

, and it is common in the Lago Puelo National Park, Chubut.

Uses

The tree is used for its high-quality timber.

References

External links

''Aextoxicon punctatum'' in Encyclopedia of the Chilean Flora

in L. Watson and M.J. Dallwitz (1992 onwards)
''The families of flowering plants''

Hansen & Rahn: Aextoxicaceae

NCBI Taxonomy Browser: Aextoxicaceae

CSDL: Aextoxicaceae
{{Taxonbar, from1=Q1070232, from2=Q292660 Berberidopsidales Flora of the Andes Flora of central Chile Trees of Chile Trees of Argentina Trees of mild maritime climate Trees of subpolar oceanic climate Flora of the Valdivian temperate forests Monotypic eudicot genera Data deficient plants Dioecious plants Taxa named by José Antonio Pavón Jiménez Taxa named by Ernest Friedrich Gilg Taxa named by Adolf Engler