Calamus (genus)
| Calamus | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Calamus | ||||||||||||
| L. |
Calamus is a genus of palm that is native to Africa and Asia. They are often climbing rattan palms . It is the main supplier of rattan along with a few other types . With 516 species it is the most species-rich genus of the palm family.
features
The representatives are extremely variable. Most of the species are climbing palms, some are also stemless (acaulescent) or upright. They grow single or multi-stemmed. They are several times blooming and dioeciously separated sexes ( diocesan ). The trunk has short or long internodes . Side shoots arise strictly axillary .
The number of chromosomes is 2n = 26.
leaves
The leaves are pinnate, rarely in two parts (bifid). Sometimes they have a terminal tendril . The leaf sheaths tear open in the acaulescent species. In the free area they are mostly densely reinforced with scattered or whorled spines. In the species Calamus polystachys , the spines are interlaced and form galleries that are colonized by ants. There is often an indument on the vaginal surface . A Ochrea is common. In some species, this can be swollen and harbor ants. A knee is present in most climbing species.
Species that lack a tendril often have a flagellum : a whip- shaped climbing aid that has emerged from a sterile inflorescence .
A petiole may be missing or well developed. It is reinforced in different ways. The rachis is often covered with distant groups of backward-pointing spines. The tendril, if present, is also covered with backward-pointing spines.
The few to numerous leaflets are simply folded, with entire margins (only bitten off in Calamus caryotoides ), linear to lanceolate or rhombic . The two terminal leaflets can be fused together on their inner edges. The leaflets are covered with hair, bristles, spines and scales in different ways.
Inflorescences
The inflorescences are axillary, but are fused with the internode and the leaf sheath of the next following leaf. Male and female inflorescences are similar to each other, but the male ones are usually branched in three orders, the female in two. The inflorescences are often whip-shaped, very rarely they can take root at their tip and thus form new vegetative shoots. A peduncle is missing or may be present, sometimes very long. It is upright or hanging and reinforced in different ways. The cover sheet is usually inconspicuous, two-keeled, tubular, closely fitting, differently reinforced or unreinforced. It is seldom inflated, papery or leathery. The bracts on the inflorescence axis resemble the previous leaf. They are close, rarely at a distance. They are reinforced in different ways, mostly tubular and remain tubular even if they tear open. In the axilla of each bract there arises a side branch of the first order or a partial inflorescence . This is often fused to a piece with the inflorescence axis, it rarely breaks through the bract. The side axis of the first order bears a double-sided, tubular front leaf and almost double-row (subdistich) standing, tubular bracts, which are unreinforced or variously reinforced. In the armpits are the side axes of the second order, which are mostly fused with the side axis of the first order. The flower-bearing axes (rachillae) are designed very differently within the genus. They can be wide or very short and drawn out. They usually have a basal, two-keeled cover sheet and conspicuous, mostly distiche, tubular bracts with triangular tips that are differently reinforced or unreinforced. The bracts are very rarely crowded and spiral. In the male inflorescences, a bract has a single male flower with a bractole , in the female inflorescences a triad of two lateral female and one central sterile male flower.
blossoms
The male flowers are symmetrical. The calyx is tubular at the base, three-lobed at the top. The crown is usually longer than the calyx and divided into three valvate lobes, with the exception of the tubular base. There are six stamens , only twelve in Calamus ornatus . They stand at the mouth of the corolla tube. The filaments are often fleshy, sometimes abruptly narrowed. The anther are medifix, short to long, and latrors or intrors. The rudiment of the stamp is small or clearly present. The pollen is ellipsoidal, bisymmetrical and has equatorial, disulcate germ openings. The sterile male flowers are similar to the fertile ones, only their anthers are empty.
The female flowers are usually larger than the male. The calyx is tubular and weakly three-lobed. The crown is hardly longer than the chalice. The six staminodes are epipetal, the filaments are free or form a short ring, the anthers are empty. The gynoeceum consists of three carpels, each with an ovule . It is spherical to ellipsoidal and covered with scales pointing downwards. The three scars are apical, fleshy, bent back and sometimes stand on a beak. The subjects are incomplete. The ovules are basal and anatropic .
Fruits and seeds
The fruit is usually solitary, rarely containing two or three seeds. The scar remains are apical. The exocarp is studded with regular rows of backward-facing scales. The mesocarp is usually thin when the fruit is ripe, an endocarp is not differentiated. The seed has a thick, sweet, sour or astringent tasting sarcotesta . The inner part of the seed is rounded, furrowed, angular or sharply winged. The endosperm is homogeneous or ruminate. The embryo is basal or lateral.
Distribution and locations
The genus has a palaeotropic distribution: One species occurs in the humid tropics of Africa. The further area extends from southern India and Ceylon via Burma and southern China via the Malay archipelago to Queensland in Australia and Fiji. It reaches the greatest biodiversity in the area of the Sunda Islands, especially in Borneo . A second diversity center is located in New Guinea .
The ecological demands are very different. However, only a few species occur in seasonally dry locations such as monsoon forests, and the genus is completely absent in semi-arid areas. Some species like Calamus erinaceus occur in mangrove- like conditions. Some species have very strict ecological requirements, such as sandstone or ultra-basic rock as a subsoil. Calamus species occur from sea level up to over 3000 m (such as Calamus gibbsianus on Kinabalu ).
Systematics
The genus Calamus is placed within the family Arecaceae in the subfamily Calamoideae , Tribus Calameae and Subtribus Calaminae . The genus is almost certainly not monophyletic , the other genera of the subtribe, according to molecular genetic cladograms , lie within the genus. The calaminae therefore break down into three large clades . The first clade includes some of the Calamus species and the genus Retispatha . The remaining three genera of the subtribes are the sister group of the remaining Calamus species.
The genus Calamus comprises 516 species in mid-2020. A list of species can be found in the World Checklist of Selected Plant Families at the Royal Botanic Gardens, Kew .
literature
- 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. 191-197.
Individual evidence
- ↑ Andrew Henderson. 2020. A Revision of Calamus (Arecaceae, Calamoideae, Calameae, Calaminae). Phytotaxa. 445 (1); 1-656. DOI: 10.11646 / phytotaxa.445.1.1
- ↑ Rafaël Govaerts (ed.): Calamus. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved August 2, 2018.
Web links
- Calamus on the homepage of the Fairchild Tropical Botanic Garden