Bonnetiaceae

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Bonnetiaceae
Bonnetia sessilis (left) and Bonnetia paniculata (right), illustration

Bonnetia sessilis (left) and Bonnetia paniculata (right), illustration

Systematics
Eudicotyledons
Nuclear eudicotyledons
Rosids
Eurosiden I
Order : Malpighiales (Malpighiales)
Family : Bonnetiaceae
Scientific name
Bonnetiaceae
Nakai

The plant family Bonnetiaceae belongs to the order of the Malpighia-like (Malpighiales). The only three genera Bonnetia, Archytaea and Ploiarium with a total of about 33 species are common in tropical South America , Southeast Asia and Malaysia . The wood is used locally as a building material because of its high durability, but has no economic significance.

description

Illustration of Bonnetia anceps

Appearance

The species of Bonnetiaceae are evergreen shrubs or usually sparsely branched trees . The tallest trees in the family are found in the species Ploiarium alterniflorum, which can grow to heights of up to 25 meters. Their heartwood is reddish dark brown and heavy. The nodes are trilacunar with three leaf trace strands, or unilacunar with one leaf trace strand. The parts of the plant are bare; only in the leaf axils are there small accumulations of multicellular trichomes called collaterals that can secrete mucilage .

leaves

The spirally arranged leaves are close together and have short stems. The leaf stalks contain a cylindrical pith layer that penetrates the stem entirely or partially. The leaves are variable in the shape of the blade and their thickness depending on the species. The leaf margin is finely serrated. The highly developed parallel nerve, which is unique to the dicotyledonous and resembles that of some monocotyledons, is striking . This characteristic differentiates the family from the tea shrub family (Theaceae).

The stomata are paracytic. In some species there are special vascular bundles with a vascular bundle sheath consisting of two concentric layers: an inner layer with several layers of fibers, and an outer layer, the endodermis, made up of thin-walled cells with Casparian stripes . There are mucous cells on the top of the mesophyll .

The species are very variable in terms of the thickness of the cuticle, the relative proportion or thickness of palisade and sponge parenchyma, and the presence of stone cells (sclereids) or crystals in the mesophyll.

Inflorescences and flowers

The hermaphroditic flowers are in zymose inflorescences . Each flower stalk arises from the axilla of a single bract , but often up to two more bracts arise from the flower stalk, which can be very close to the calyx. The perianth is clearly differentiated into two petal circles. The five sepals (sepals) are free or only fused at the base. They are fleshy (about 10 to 20 cells thick), scale-shaped, and often different. While the sepals of Bonnetia and Archyteae are retained when the fruit is ripe, they fall off when the fruit is ripe in Ploiarium . With Bonntia the sepals are often reddish. In Bonntia kathleenae and Bonntia rubicunda collaterals are found on the sepals.

The crown is turned. The five petals (petals) are strongly thickened (thicker than the sepals), fleshy (about 8 to 15 cells thick) and scale-shaped. They are purple, mottled white, reddish or yellow. In Bonntia bolivarensis or Bonntia steyermarkii they are slimy.

The stamens are numerous, with Bonnetia are in a single stamen circle, from a row two to four wide. Often several are fused together to form a tube at the base. The row forms a complete circle at the base of the flower. With Archytaea and Ploiarium the stamens are in five groups. In Archytaea the lower two thirds are fused. The anthers are fused with the filaments at the base. They consist of the usual two counters and four pollen sacks. Often the lower pollen sacs are shorter than the upper ones. The pollen grains are between 28 and 60 micrometers long with a round opening. The genera Archytaea and Ploiarium form disc-shaped nectaries between the groups of stamens at the flower base .

The ovary consists of three (rarely four) carpels in Bonnetia and five carpels in the other two genera. The stylus is round, for example fasciculata but flattened. The punctiform scar is papillae . The numerous ovules are anatropic. The micropylene canal is formed by the external integuments (exostomal micropyle).

Fruits and seeds

The septicidal capsule fruits , a sub-form of the split capsules , contain many seeds . The seeds are unusually small, with an exceptionally thick woody seed coat .

ingredients

Bonnetiaceae are rich in xanthones and anthraquinones , which are also found in the closely related Clusiaceae and St. John's wort family (Hypericaceae).

Spread and endangerment

Distribution area of ​​the Bonnetiaceae

The Bonnetiaceae family is distributed in northern South America and the Caribbean, as well as in Southeast Asia, more precisely in West Malaysia, Cambodia, the Moluccas and New Guinea. The species of the genus Bonettia are found only in South America and with one species in Cuba, whereas Archytea and Ploiarium are also found in Asia. The diversity center of Bonnetia, that is, the area where most of the species are native, is located in the highlands of Guayana , where there are 27 species, all but Bonnetia paniculata there endemic are.

Archytea prefers open habitats on nutrient-poor soils . Ploiarium grows in the lowlands near the sea on marshy soil or on nutrient-poor sandy soil on Borneo. Bonnetia mainly grows on the table mountains in Guyana, where they thrive on damp scree slopes of sandstone and quartz sands.

Because many species in the Bonnetiaceae family are endemic, they are particularly endangered. The IUCN lists a total of 13 species from the genus Bonnetia on its Red List of Endangered Species . The species no longer found since 1978 Bonnetia ptariensis even as critically endangered ( critically endangered ) out. No species of the genera Archytea and Ploiarium is listed with the IUCN.

Systematics

The Bonnetiaceae are closely related to the Clusiaceae and the paraphyletic tea bush plants (Theaceae). A phylogenetic study from 2004 also revealed indications of a close relationship with the Kielmeyeroideae and the Ternstroemiaceae , but these are uncertain.

The relationship with the St. John's wort family (Hypericaceae) and the Podostemaceae seems certain. A 2007 cladogram looks like this:



Clusiaceae


   

Bonnetiaceae


   

Hypericaceae


   

Podostemaceae



Template: Klade / Maintenance / 3

An excerpt from the Wurdack & Davis 2009 cladogram :


other Malpighiales


 Clusioid clade 



Bonnetiaceae


   

Clusiaceae



   

Calophyllaceae


   

Hypericaceae


   

Podostemaceae






Template: Klade / Maintenance / Style

As with almost all tropical plant families, the internal system of the Bonnetiaceae is controversial. In 1996 Dickison and Weitzmann combined six genera in the family. A year later Weitzmann and Stevens deleted the genera Acopanea Steyerm. , Neblinaria Maguire and Neogleasonia Maguire but now three genera with a total of around 33 species remained:

Illustration of Archytaea triflora (left)
Branch with leaves and blossom of Bonnetia anceps
Bonnetia roraimae on the Roraima tepui , habitus
Bonnetia stricta
Ploiarium alternifolium
  • Ploiarium Korthals : It contains two or three species that occur in Southeast Asia to New Guinea:

Web links

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

literature

  • William C. Dickison, Anna L. Weitzmann: Floral morphology and anatomy of Bonnetiaceae . In: Journal of the Torrey Botanical Society . tape 125 , no. 4 , p. 268-286 .
  • Anna L. Weitzmann, Klaus Kubitzki, PF Stevens: Bonnetiaceae . In: Klaus Kubitzki (Ed.): The Families and Genera of Vascular Plants . tape 9 . Springer, Berlin / Heidelberg 2007, ISBN 3-540-32214-0 , pp. 36-39 , doi : 10.1007 / 978-3-540-32219-1 .

Individual evidence

  1. ^ Search for "Bonnetia" in the IUCN Red List of Threatened Species .
  2. ↑ Isolda Luna, Helga Ochoterena: Phylogenetic relationships of the genera of Theaceae based on morphology . In: Cladistics . tape 20 , no. 3 , June 2004, p. 223-270 , doi : 10.1111 / j.1096-0031.2004.00024.x .
  3. ↑ Malpighiales. Angiosperm Phylogeny Group, accessed August 26, 2007 .
  4. ↑ Kenneth J. Wurdack & Charles C. Davis: Malpighiales phylogenetics: Gaining ground on one of the most recalcitrant clades in the angiosperm tree of life . In: American Journal of Botany . 2009, Volume 96, pp. 1551–1570, section Systematics ( PDF; 788 kB ( Memento of the original dated February 6, 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link accordingly Instructions and then remove this notice. ). @1@ 2Template: Webachiv / IABot / www.people.fas.harvard.edu
  5. ↑ William C. Dickison, Anna Weitz man: Comparative anatomy of the young stem, and leaf node of bonnetiaceae, Including observations on a foliar endodermis . In: American Journal of Botany . tape 83 , no. 4 , April 1996, pp. 405-418 , doi : 10.2307 / 2446210 .
  6. ↑ Anna Weitzmann, PF Stevens: Notes on the circumscription of Bonnetiaceae and Clusiaceae, with taxa and new combinations . In: BioLlania . tape 6 . Edición Esp. , 1997, p. 551-564 .
  7. ^ A b David John Mabberley: Mabberley's Plant-Book. A portable dictionary of plants, their classification and uses . 3. Edition. Cambridge University Press 2008, ISBN 978-0-521-82071-4 .
This version was added to the list of articles worth reading on September 3, 2007 .