Areceae

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Areceae
Betel nut palm (Areca catechu)

Betel nut palm ( Areca catechu )

Systematics
Monocots
Commelinids
Order : Palm- like arecales
Family : Palm family (Arecaceae)
Subfamily : Arecoideae
Tribe : Areceae
Scientific name
Areceae

The Areceae are a tribe of the palm family (Arecaceae). They occur in the Indo-Pacific region and are morphologically characterized primarily by the presence of only one ovule or one seed per fruit .

features

The representatives of the Areceae are small to large palm trees, they can be stemless, upright or, rarely, climbing. They can be reinforced or unreinforced. The leaves are pinnate or whole and two-part. The tips of the leaflets are whole or bitten off. The leaf sheaths usually form a crown shaft, but this can also be absent.

The inflorescences are under or between the leaves, they are spike-shaped or strongly branched. The bracts on the inflorescence usually consist of a cover sheet and a single bract on the inflorescence stalk . The flowers are in the lower area of ​​the inflorescence in triads, distally then often only individually and in pairs, then only more than male flowers. The triads are often sunk into the axis. The female flowers have free or fused petals in the lowest area . The staminodes are mostly free, very rarely fused to form a conspicuous ring. The gynoeceum is pseudomonomer, so it appears to consist of only one carpel .

The scar remains on the fruit are basal or apical. The exocarp is smooth.

distribution

The representatives are based in the Indo-Pacific region. The distribution area extends from Madagascar over the south of India and Southeast Asia in the north almost to Japan, in the south over Indonesia and the north of Australia to the north island of New Zealand. The biodiversity is particularly high on the arch of the islands in the western Pacific.

Systematics

The Areceae as defined by Dransfield et al. (2008) are identified as natural relatives ( Monophylum ) in most studies . Because of their distribution and characteristics, the Areceae are also known as the Indo-Pacific pseudomonomers clade. Their exact position is not clearly established, but their membership of the core arecoid clade within the Arecoideae is . A wide variety of sister groups were proposed.

Within the Areceae tribe, Dransfield et al. (2008) eleven subtribes. The relationships between these tribes are largely unclear. However, there are moderately secured clades from western Pacific subtribes: Rhopalostylidinae, Basseliniinae, Carpoxylinae, Laccospadicinae, Clinsopermatinae, Ptychospermatinae, Archonotphoenicinae as well as Dransfieldia and Heterospathe . In addition, there are ten genera that clearly belong to the Areceae, but cannot be assigned to any subtribe. These are therefore listed as incertae sedis .

Due to the uncertain relationship, the subtribs are listed in alphabetical order:

Archontophoenicinae

The representatives are medium to large palm trees. The leaves are pinnate, the leaflets with entire margins. The crown shaft is always well developed. The inflorescences are branched two to three times. The cover leaf and bract on the peduncle are similar. The gynoeceum is pseudomonomer. Representatives are limited to New Guinea, Australia and New Caledonia. A group of four of the five species is often viewed as monophyletic, Actinorhytis is less often part of the same clade, their position is still uncertain.

Arecinae

The three genera are native to the rainforests of Southeast Asia and Malesia , some of which are still native to the western Pacific. They lack the bracts on the peduncle. They are small to medium-sized palm trees. The leaf sheaths almost always form a crown shaft. The inflorescence is spiky or branched one to three times. There is a membranous cover sheet that includes the inflorescence to the anthesis . The scar remains on the fruit are apical.

Basseliniinae

The group's area includes New Caledonia, Vanuatu, Fiji, the Solomon Islands and the Bismarck Archipelago. The incompletely tubular cover sheet on the inflorescence is characteristic. The endocarp is often ornamented. The palms are small to medium-sized, a crown shaft is formed, is only absent in Cyphosperma and is poorly developed in Burretiokentia . The inflorescences are heavily branched. The group's monophyly is not clearly understood, but it is morphologically well defined.

Carpoxylinae

The representatives are sturdy palms with pinnate leaves. The tips of the leaflets are entire. The leaf sheaths form a crown shaft. The cover sheet is much shorter than the bracts on the peduncle. There are one or two enlarged bracts that completely envelop the inflorescence at the bud stage. The three genus are very scattered in the western Pacific: one on Vanuatu, one on Vanuatu and Fiji, and the third on the Ryūkyū Islands .

Clinospermatinae

The representatives are medium-sized palms with pinnate leaves. The tips of the leaflets are entire. The leaf sheaths usually form a distinct crown shaft. The inflorescences are usually strongly branched. The cover sheet is completely tubular. There are usually two bracts on the peduncle. The anthers connectives almost completely lacking. The subtribe is endemic to New Caledonia .

Dypsidinae

Dypsis lutescens

The representatives are small to very large palm trees, without a trunk or upright or rarely climbing. The leaves are in two parts and have entire margins, or pinnate. The leaf sheaths often form a crown shaft. The inflorescences are hermaphroditic, they are rarely unisexual. There are 3 to 6 stamens, rarely more than 50. In general, there is a great morphological diversity within the subtribes. They only have in common the occurrence in Madagascar. The monophyly of the subtribes is not definitely confirmed.

Laccospadicinae

Howea forsteriana

The representatives are rather small and slim. Characteristic features are: the leaf sheaths do not form a crown shaft, the inflorescences are always spike-shaped and the flower triads sit in pits. The cover sheet is preserved, mostly it is hidden between the leaf sheaths. The species occur in New Guinea, the Moluccas, in Australia and on Lord Howe Island . The monophyly of the group is assured, with the exception of the assignment of calyptrocalyx , which is not always assigned to this group.

In Genera Palmarum 2 the subtribe was still carried under the name Linospadicinae. However, since this is an illegitimate name, the name Laccospadicinae was introduced for the subtribes in 2011 and adopted by Baker and Dransfield in their family classification in 2016.

Oncospermatinae

The representatives are medium-sized to large, upright palms that are armed with spines, at least when young. The leaf sheaths form a distinct crown shaft. The inflorescences are between the leaves, are hermaphroditic and at least twofold branched. The cover leaf and bract on the peduncle are similar in shape and size, and both usually fall off during flowering. The male flowers are mostly asymmetrical. The representatives are based on the islands of the Indian Ocean and the adjacent areas of the Asian mainland and western Malesia .

Ptychospermatinae

The representatives are small to large palms with pinnate leaves and torn leaf tips, and a clearly developed crown shaft. The inflorescences are widely branched. Cover sheet and bract on the peduncle are similar, sit close together; however, the bract can also be much larger and penetrate the previous sheet. The male flowers are larger than the female and are cartridge-shaped. There are numerous stamens. The subtribe is widespread in eastern Malesia and extends to Fiji, Samoa and Australia. There is a disjoint occurrence in Palawan (Philippines) and one in the Carolines . The subtribe is seen in most studies as monophyletic.

Rhopalostylidinae

Rhopalostylis baueri

The representatives are medium-sized, monocular palms with pinnate leaves, the pinnate leaves have entire ends. The leaf sheaths form a clear, short and compact crown shaft. The inflorescences are between the leaves, the peduncle is very short. The cover leaf and bract on the inflorescence stalk cover the inflorescence in the bud stage. The male flowers are asymmetrical and have 6 to 10 stamens.

Verschaffeltiinae

The representatives are small to medium-sized palms armed with thorns. The leaf sheaths usually do not form a clear crown shaft. The inflorescences are between the leaves, bear flowers of both sexes and at least twofold branched. The cover sheet is usually much longer than the bract on the peduncle, it is usually persistent. The male flowers are mostly symmetrical. The subtribe consists of four monotypical genera, all of which are limited to the Seychelles .

Incertae sedis Areceae

The following genera are placed in the Areceae as incertae sedis without being assigned to a subtribe:

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. 2nd edition, Royal Botanic Gardens, Kew 2008, ISBN 978-1-84246-182-2 , p. 493 ff.

Individual evidence

  1. ^ John Dransfield, Natalie W. Uhl, Conny B. Asmussen, William J. Baker, Madeline Harley, Carl E. Lewis: Validation of Laccospadicinae (Arecaceae: Areceae). In: Palms. Volume 55, 2011, p. 199. palms.org (PDF).
  2. ^ William J. Baker, John Dransfield: Beyond Genera Palmarum : progress and prospects in palm systematics . Botanical Journal of the Linnean Society, 2016, doi : 10.1111 / boj.12401

Web links

Commons : Areceae  - collection of images, videos and audio files