Screw trees

from Wikipedia, the free encyclopedia
Screw trees
Pandanus tectorius, habit and inflorescence.

Pandanus tectorius , habit and inflorescence.

Systematics
Subdivision : Seed plants (Spermatophytina)
Class : Bedecktsamer (Magnoliopsida)
Monocots
Order : Screw tree-like (Pandanales)
Family : Screw tree plants (Pandanaceae)
Genre : Screw trees
Scientific name
Pandanus
Parkinson's

The screw trees ( Pandanus ), also called screw palms or pandans , are a genus of plants from the family of the screw tree plants (Pandanaceae) in the order of the screw tree-like (Pandanales). They have a paleotropic distribution.

description

Screw tree species grow as evergreen , tree- or shrub-shaped, perennial plants . They have simple or branched trunks and sometimes aerial or stilt roots . The leaves, which are arranged in a triple spiral, are large, simple, linear, thorny on the edge and the central rib.

Screw tree species are dioecious separately sexed ( dioecious ). Terminal inflorescences are formed. The unisexual flowers are without a flower cover . The innumerable, tiny, not clearly distinguishable, mostly stalked male flowers , with one to several or very many, free or overgrown stamens in doldy or racemose groups and rarely also pestillos, are in mostly branched, dense panicles or bunches with colored bracts in and under the inflorescence. The female, just distinguishable and seated flowers, with several free or fused carpels with mostly just an ovule and seated scars or short pencils , bear a simple piston or in simple or compound head . Staminodes can also rarely occur. Simple, solitary or compound and multi-seeded stone fruits are formed, which are in a fruit association ; more precisely stand together in a stone fruit bandage .

distribution

The genus Pandanus includes more than 600 species in the warmer countries of the eastern hemisphere; most of them are common on the islands of the Indian Ocean and the Mascarene Islands , where they grow near the sea and sometimes cover large stretches of land with impenetrable vegetation .

use

Some species are used in a variety of ways, such as Pandanus utilis , Pandanus amaryllifolius , Pandanus odorifer , Pandanus furcatus or Pandanus tectorius .

Systematics

The genus Pandanus was established in 1773 by Sydney C. Parkinson in Journal of a voyage to the South Seas , p. 46. Type species is Pandanus tectorius Parkinson . Synonyms for Pandanus Parkinson are Keura Forssk. , Dorystigma Gaudich. , Foullioya Gaudich. , Heterostigma Gaudich. , Souleyetia Gaudich. , Vinsonia Gaudich.

species

Here is a list of the species recognized in the Kew Checklist 2007, whereby in addition to the botanical author abbreviation, the publication with the year of publication of the first description is given (no longer corresponds to the Kew Checklist version in 2011 or 2017):

Pandanus candelabrum , habitus
Pandanus tectorius , collective fruit
Pandanus utilis , habitus
Pandanus utilis , infructescence

photos

  • Screw tree ( Pandanus spec.), Trunk

  • Screw tree ( Pandanus spec.), Habitus

  • Screw tree ( Pandanus spec.), Stilt roots.

Individual evidence

  1. ↑ RMT Dahlgren, HT Clifford, P.F. Yeo: The Families of the Monocotyledons. Springer, 1985, ISBN 978-3-642-64903-5 , (Reprint), p. 481.
  2. ^ AB Rendle: The Classification of Flowering Plants. Second Edition, Volume 1, 1930, ISBN 0-521-06056-7 (Reprint), pp. 187, 194 ff.
  3. ↑ Pandanus in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland.
  4. ^ Pandanus at Tropicos.org. Missouri Botanical Garden, St. Louis
  5. ↑ a b c Rafaël Govaerts (Ed.): Pandanus. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved March 17, 2020.

Web links

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