Asterogyne

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Asterogyne
Asterogyne martiana

Asterogyne martiana

Systematics
Commelinids
Order : Palm- like arecales
Family : Palm family (Arecaceae)
Subfamily : Arecoideae
Tribe : Geonomateae
Genre : Asterogyne
Scientific name
Asterogyne
H. Wendl. ex Hook.f.

Asterogyne is a neotropical genus of palm . There are small palm trees in the undergrowth of the woods.

features

The Asterogyne species are small to medium-sized palm trees. They only form a single trunk. This is usually upright, rarely lying slightly down at the base. The trunk is smooth, brown to brownish cream in color. At the base of some species form vegetative side branches that do not develop into independent trunks. The side branches of Asterogyne ramosa are particularly numerous with 5 to 30 branches that start around 20 to 40 cm below the crown shaft. Each of these side branches has 4 to 7 small simple leaves and forms numerous roots. The palms are unarmed, blooming several times and single-sexed ( monoecious ).

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

The number of chromosomes is unknown.

leaves

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, tubular and tears open opposite the leaf stalk. The edges of the leaf sheath are stiff and fibrous. The petiole is slender, hairless or hairy brown. The leaf blade is usually bifid and simple, but can also be torn lengthways with age. In the species examined, a chlorophyll-free hypodermic cell layer is only formed on the underside of the leaf. In mesophyll none palisade layer is formed, numerous fibers having rather wide lumens are individually embedded in the mesophyll.

Inflorescences

The inflorescences are always between the leaves (interfoliar), single and they are always proterandrisch . Asterogyne guianensis and Astrogyne spicata have spikes , while the inflorescences of the other species are branched once. The peduncle is long and slender. The cover sheet is fibrous to membranous and starts at or near the base of the peduncle. The inflorescences themselves are enclosed by - depending on the species - one or two bracts on the inflorescence axis . These are tubular and paper-like to membranous. The young, small inflorescence is straight and enclosed in these bracts. It then quickly elongates and appears through a crack at the end of the persistent bracts. At flowering time the inflorescences are upright, when the fruit ripens, they become drooping. In the species with branched inflorescence the inflorescence axis is usually well developed, only in Asterogyne martiana it can be very short, so that the side axes appear to arise directly from the inflorescence stalk.

The axes are salmon pink to pink at flowering time, and when the fruit ripens they turn brown to reddish brown.

The flowers are in clusters, which are arranged in a spiral on the flower-bearing axes (rachillae). In the bud state, the pits are covered by a rounded lower lip, which is covered by a short upper lip. The lower lip rolls back during flowering, which releases the flowers. As is common with the Arecoideae , the pits bear flower triads of one female and two male flowers. Each triad corresponds to a short wrap . The lower lip corresponds to the bract of the first male flower or the wrap. There are three other bracts in the pit: the largest corresponds to the bract of the second male flower, the middle one to the bract of the female flower and the smallest is the bract of the female flower.

blossoms

Male flowers

The two male flowers of a triad are to the side of the female flower. The three sepals are fused at the base and free at the top. The three petals are fused at the base, apical valvat . The number of stamens is between six and 27, depending on the species. The higher numbers occur in the species with annual inflorescences, this characteristic is considered to be derived within the tribe Geonomateae . The stamens are fused to form a tube up to over half their length, at the tip they are free. The anthers of some species are motile. The counters are separated by a two-way connective, this is considered a synapomorphism of the genus. The connective is tannic . In Asterogyne martiana the connective is swollen. In the bud, the anthers are bent inward and intrors. When they bloom, they protrude outwards and are extrors. In the center of the flower there is a three-lobed rudiment of pistil, which is fused with the stamen up to the middle.

Female flowers

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

Between the sides of the carpels there is a clearly defined septal nectarium , the three openings are at the tip of the ovary.

The stylus is basal to lateral. The three scar branches are papillae and curved backwards at the time of flowering.

There are between 5 and 22 staminodes , which have grown together to form a tube up to the middle.

Fruits and seeds

Asterogyne forms drupes . These are ellipsoidal to ellipsoidal-egg-shaped 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 fruits contain a single seed. They are conspicuously keeled at the top. The seed is ellipsoidal and slightly flattened dorsiventrally. The endosperm is homogeneous. The embryo is basal.

Locations

They are palm trees of the undergrowth of forests. Asterogyne martiana and Asterogyne ramosa can dominate the understory. Asterogyne martiana grows in the understory of lowland rainforests that are not flooded, rarely along rivers or in seasonally flooded locations. They mainly thrive at altitudes of 200 to 400 meters. In Costa Rica and Colombia, the species Asterogyne martiana rises to an altitude of 1400 meters.

Systematics and distribution

The genus Asterogyne is monophyletic . Asterogyne H. Wendl. ex Hook. f. belongs to the tribe Geonomateae in the subfamily Arecoideae within the palm family (Arecaceae). Their position within the tribe is not secured. They could be the sister group of a clade from Geonoma , Calyptronoma and Calyptrogyne . There are three clades within the genus . The first clade consists of Asterogyne guianensis and Asterogyne spicata , which are characterized by their annual inflorescences and male flowers with over 21 stamens. The second clade consists of Asterogyne ramosa and Asterogyne yaracuyense , which grow in the mountain forests of Venezuela and have inflorescence stalks over 85 centimeters long. The third clade was formed by Asterogyne martiana .

The neotropical genus Asterogyne is common in central and northern South America. One species ( Asterogyne martiana ) is widespread. Three species are endemic to the Venezuelan coastal cordillera . One species occurs only in French Guiana .

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

supporting 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

Individual evidence

  1. ↑ Rafaël Govaerts (ed.): Asterogyne. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved March 12, 2011.

Web links

  • Asterogyne on the homepage of the Fairchild Tropical Botanic Garden