Brachynema (Olacaceae)

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Brachynema
Systematics
Class : Bedecktsamer (Magnoliopsida)
Eudicotyledons
Nuclear eudicotyledons
Order : Sandalwoods (Santalales)
Family : Olacaceae
Genre : Brachynema
Scientific name
Brachynema
Benth.

Brachynema is a genus of small deciduous trees from the tropical rainforest of South America. It was long considered monotypical until a second species was described in 1995.

The name of the genus is homonymous to the genus Brachynema (family of stink bugs or Pentatomidae).

features

These are small trees or bushes with a stature height of mostly 3 to 5, occasionally 8, rarely up to 10 meters. They grow upright and are not very branched, with a roughly cylindrical trunk and are usually quite sparsely leafy. The alternate leaves are stalked, their outline elongated ovate to lanceolate, pointed at the front, with a wedge-shaped base. The leaf margin is almost entire to shallow, the tips or ends of the leaf veins each with a gland. They are very variable in size, even on the same tree, and can be (10) 20 to 40 centimeters in length by (4) 5 to 12 (-20) centimeters wide. The midrib of the leaf is clear on both the upper and the lower side, there are 8 to 10 (rarely up to 13) secondary leaf nerves that are bent towards the tip of the leaf and converge at the edge. The petiole is slightly swollen both at the base and at the base of the leaf.

The flowers are bisexual. They sit in bracteless, umbrella-shaped inflorescences of up to 20 flowers, in Brachynema ramiflorum directly on the older, leafless trunk sections ( kauliflor ), in Brachynema axillare in leaf axils on young twigs. The greenish-white calyx is dome-shaped with five short calyx lobes or almost entire. It extends noticeably after flowering until the fruit is ripe. The corolla is fused into a long tube, which ends at the tip to five pointed corolla lobes. The crown is white in color, with Brachynema ramiflorum noticeably darkly striped with rows of hairs inside, with Brachynema axillare white with a purple base, the corolla tube is about 2.5 to 3 centimeters long and about 4 millimeters in diameter. The five stamens are fused with the corolla tube at the base, they sit in the spaces between the corolla lobes. The Upper permanent, sedentary ovary has four or five subjects, with an axillary hanging ovule in each of them. The scar is seated, head-like and barely articulated. The solitary stone fruit is almost spherical with a hard, purple to green fruit skin, and when the fruit is ripe it is almost enclosed by the elongated calyx.

distribution

The genus Brachynema occurs only in the Amazon basin in South America. Brachynema ramiflorum is endemic to Brazil, in Amazonas (Brazil) , Mato Grosso and Pará . Brachynema axillare grows in the western Amazon basin, Amazon (Brazil), Amazon (Venezuela), and the Ucayali region of Peru.

Location

The species grow, relatively rarely, in the undergrowth of tropical lowland rainforests.

Phylogeny and Kinship

The family position of the genus is still disputed today. Morphological features such as the cupped, glandular leaf margin and the multiple ovary with axillary ovules are not only in the family Olacaceae, but also within the whole order of the sandalwood-like features deviating from the basic pattern, they cause some authors to doubt the usual arrangement in the family Olacaceae. According to a more recent, previously unpublished phylogenomic analysis, sister group is the genus Maburea with the only species Maburea trinervis . This places the species in the family Olacaceae in a broader sense. The family was split into seven smaller families by Daniel L. Nickrent and colleagues in 2010, which would put the genus in the new family Erythropalaceae. However, this split was not recognized by the Angiosperm Phylogeny Group in its fourth revision in 2016, which most botanists consider to be decisive.

species

There are only two types:

Individual evidence

  1. ^ A b Hermann Otto Sleumer: Olacaceae . In: The New York Botanical Garden (Ed.): Flora Neotropica . tape 38 . New York Botanical Garden Press, New York 1984, ISBN 0-89327-254-X , pp. 1-158 , JSTOR : 4393778 .
  2. ^ A b Rodrigo Duno de Stefano, Paul E. Berry, Giovannina Orsini Velásquez: A New Species of Brachynema (Olacaceae) from South America . In: Novon . tape 5 , no. 3 , 1995, p. 238-240 , JSTOR : 3392256 .
  3. ^ Job Kuijt, Bertel Hansen: Flowering Plants. Eudicots: Santalales, Balanophorales . In: Klaus Kubitzki (Ed.): The Families and Genera of Vascular Plants . tape 12 . Springer, Cham 2014, ISBN 978-3-319-09296-6 , pp. 130-131 , doi : 10.1007 / 978-3-319-09296-6 .
  4. ^ Valéry Malécot, Daniel L. Nickrent, Pieter Baas, Leen van den Oever, Danielle Lobreau-Callen: A Morphological Cladistic Analysis of Olacaceae . In: Systematic Botany . tape 29 , no. 3 , 2004, p. 569-586 , JSTOR : 25063993 .
  5. ^ Daniel L. Nickrent, Kurt Maximilian Neubig, Huei-Jiun Su: Multigene phylogeny places Brachynema in Erythropalaceae (Santalales). Summary, Conference Paper, Botany 2016 (Savannah, Georgia).
  6. ^ Daniel L. Nickrent, Valéry Malécot, Romina Vidal-Russell, Joshua P. Der: A revised classification of Santalales . In: Taxon . tape 59 , no. 2 , 2010, p. 538-558 , doi : 10.2307 / 25677612 .
  7. ^ The Angiosperm Phylogeny Group: An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV. In: Botanical Journal of the Linnean Society . tape 181 , no. 1 , May 2016, p. 1-20 , doi : 10.1111 / boj.12385 .