Asterogyne

Asterogyne is a neotropical palm genus. There are small palm trees in the understory of rainforests.

• 4.1 Notes and references

Features

The representatives are small to medium-sized palm trees. They form only a single root. This is usually erect, rarely slightly decumbent at the base. The trunk is smooth, brown cream to brownish. At the base form some species vegetative lateral branches that do not develop into einständigen tribes. Especially numerous are the side branches at Asterogyne ramosa with 5 to 30 branches that start about 20 to 40 cm below the crown shaft. Each of these side branches bears 4-7 small simple leaves and forms numerous roots. The palm trees are unarmed, several times flourishing and monoecious getrenntgeschlechtig ( monoecious ).

Some species form at the base of the stem adventitious roots that form a cone. In Astergoyne guianensis these aerial roots are up to 90 cm long.

The chromosome number is unknown.

At least the younger leaves are in a spiral arrangement and rather upright and are purple. The crown consists of 6 to 31 leaves. The leaf sheath is brown to cream-colored, short, Roehrig and tears over the petiole on. The edges of the leaf sheath are stiff - fibrous. The petiole is slender, hairy bald or brown. The leaf blade is usually bifid and simple, but can be torn in old age along. In the studied species, a chlorophyll hypodermal cell layer is formed only on the underside of leaves. In mesophyll no palisade layer is formed, numerous fibers with rather wide lumen are embedded individually in the mesophyll.

Inflorescences

The inflorescences are always among the leaves ( interfoliar ), individually and they are always proterandrous. Asterogyne guianensis and Astrogyne spicata own ears, while the inflorescences of the other species are even branched. The inflorescence stalk is long and slender. The cover page is fibrous and membranous, and is applied at or near the base of the inflorescence stem. The inflorescences are themselves of - depending on the type - including one or two bracts of the inflorescence axis. These are Roehrig and papery to membranous. The young, small inflorescence is enclosed straight and in these bracts. He then extended rapidly and comes through a crack at the end of the persistent bracts revealed. In its heyday, the inflorescences are upright to the fruit ripening turns they will be suspended. For species with branched inflorescence, the inflorescence axis is usually well educated, only at Asterogyne martiana they can be very short, so that the side axes seemingly emanate directly from the inflorescence stalk.

The axes are in the heyday salmon- pink to pink, to fruit ripening turns they are brown to reddish brown.

The flowers are in Grupben that are spirally arranged on the flower-bearing axes ( Rachillae ). The pits are covered in buds state of a plump lower lip, which is covered by a short upper lip. The lower lip curls back in the heyday, so the flowers are free. The pits bear - as with the Arecoideae usual - flowers triads from a female and two male flowers. Each triad corresponds to a short winding. The lower lip corresponding to the support page of the first male flower or the roll. There are three other bracts in the pit: the largest corresponds to the support sheet of the second male flower, the middle of the bract of the female flower and the smallest is the cover page of the female flower.

Flowers

The two male flowers of a triad are the side of the female flower. The three sepals are fused at the base and top free. The three petals are fused at the base, apically valvat. The number of stamens is depending on the type of between six and 27 The higher figures occur in species with inflorescences aged men, this feature applies within the tribe Geonomateae as derived. The stamens are up over half of its length fused into a tube at the top they are free. The anthers of some species are mobile. The counters are separated by a connective zweizipfeliges, this is regarded as a synapomorphy of the genus. The connective is tannic. In Asterogyne martiana the connective is swollen. In the bud the anthers are bent inwardly and introrse. At flowering, they project outwards and are extrors. In the center of the flower is a three-lobed stamp rudiment, which is fused to the middle with the stamen tube.

The three sepals are free and imbricat, the three petals are fused to one half. The carpels are alternating with the petals. The ovary is dreifächrig and upper constant. Each carpel contains a hanging, anatrope, crassinucellate ovule. Only one ovule per ovary matures. The ovule has only one integument, which is well differentiated and in the middle of five to six cell layers thick, near the micropyle six to ten cell layers.

Between the sides of the fruit leaves a clearly pronounced Septalnektarium, the three ports are located at the tip of the ovary.

The stylus is basal to lateral. The three stigmas papillose branches are bent and the heyday backwards.

There are 5-22 staminodes, which are fused to the middle to form a tube.

Fruit and seeds

Asterogyne forms drupes. These are ellipsoidal to ellipsoidal, ovoid and have a purple, black or garnet red color. The surface is smooth. The mesocarp is fleshy and juicy, it has an inner layer of longitudinal fibers. The endocarp is thin, crusty and shiny. The fruit contains a single seed. You are keeled conspicuously at the top. The seed is ellipsoidal and slightly flattened dorsiventral. The endosperm is homogeneous. The embryo sits basal.

Dissemination and locations

Asterogyne is found in Central and northern South America. One type ( Asterogyne martiana ) is widespread. Three species are endemic to Venezuela, where they occur in the Coastal Cordilleras. One type occurs only in French Guiana.

They are palm trees of the undergrowth of forests. Asterogyne martiana and Asterogyne ramosa can dominate in the understory. Asterogyne martiana grows in the understory of lowland tropical forests that are not flooded, rarely along rivers or seasonally flooded sites. The main range is 200 to 400 m above sea level. In Costa Rica and Colombia, the nature rises to 1400 m above sea level.

System

Asterogyne is classified within the palm family ( Arecaceae ) in the subfamily Arecoideae, Tribe Geonomateae. The genus is monophyletic. Their position within the tribe is not secured. You could be the sister group of a clade from Geonoma, Calyptronoma and Calyptrogyne.

In the World Checklist of Selected Plant Families of the Royal Botanic Gardens, Kew, the following types are recognized: These types are based on the generic revision of Stauffer et al., 2003.

• Asterogyne guianensis: only from two sites in French Guiana known, are 200 kilometers away from each
• Asterogyne martiana: from Belize to Bolivia widespread
• Asterogyne ramosa: limited to the cloud forests of the Peninsula de Paria in the state of Sucre ( Venezuela), 730-1250 m above sea level
• Asterogyne spicata: limited to the Guatopo National Park in the state of Miranda ( Venezuela), 600 to 1100 m in the border area of lowland rainforest to cloud forest.
• Asterogyne yaracuyense: in the cloud forests of Cerro La Chapa and Cerro Zapatero (Venezuela )

Within the genus there are three clades. The first clade consists of Asterogyne guianensis and Asterogyne spicata, which are characterized by eared inflorescence and male flowers with 21 stamens. The second clade consists of Asterogyne ramosa and Asterogyne yaracuyense that grow in the cloud forests of Venezuela and have more than 85 cm long inflorescence stems. The third clade was formed by Asterogyne martiana.

Documents

• John Dransfield, Natalie W. Uhl, Conny B. Asmussen, William J. Baker, Madeline M. Harley, Carl E. Lewis: Genera palmarum. The Evolution and Classification of Palms. Second edition, Royal Botanic Gardens, Kew 2008, ISBN 978-1-84246-182-2, pp. 480-482.
• Fred W. Stauffer, Conny B. Asmussen, Andrew Henderson, Peter K. Endress: A revision of Asterogyne ( Arecaceae: Arecoideae: Geonomeae ). Brittonia, Volume 55, 2003, pp. 326-356. doi: 10.1663/0007-196X (2003) 055 [ 0326: AROAAA ] 2.0.CO; 2