Screw tree plants
|Screw tree plants|
Pandanus humilis , illustration
The screw tree plants (Pandanaceae), also seldom referred to as pseudo palm plants or piston palm plants , are a family in the order of the screw tree-like (Pandanales) within the monocotyledons . This small family contains only four genera with around 800 to 885 species. Of some species, the leaves are processed, and some species are ornamental plants for parks and gardens, and of one species, varieties are used as house plants.
Habit and leaves
The species of the family are evergreen , woody plants that grow tree-shaped, shrub-shaped or as lianas ; some types are epiphytes . There is no secondary growth in thickness and therefore one does not speak of trees. In many species aerial or stilt roots are formed. Some species are helophytes and thrive in shallow salt water. If stems are present then they are usually single or sometimes bifurcated. The shoot axes are often curled by the ring-shaped leaf scars.
The alternate and seemingly schraubig (hence the German name), but in fact rarely two, usually three or four lines rarely arranged leaves are sessile and simple. There are open leaf sheaths. The hairless, sometimes floured, leathery leaf blade is linear to lanceolate, often very long and sometimes keeled on the underside and often ends in a spiked tip. Often the leaf blade is serrated on the edge and often also on the midrib; the leaf margin can also be whole. There is parallel vein , but there are also many horizontal secondary leaf veins . Tetracytic stomata are present.
Inflorescences and flowers
The taxa are mostly separate sexes either dioecious ( dioecious ) or monoecious ( monoecious ). On an inflorescence there are usually only flowers of one sex; the male and female inflorescences look different. Very few Freycinetia species have hermaphroditic flowers. The terminal or lateral, mostly branched total inflorescences are composed of racemose , spike-like , head-shaped or piston-shaped partial inflorescences ; sometimes the inflorescence is simple, especially on female inflorescences. There are bracts (called spathe here), which in some species can be large and intensely colored.
The flowers are mostly unisexual, but hermaphroditic flowers are also found in some species. In many taxa no bracts are recognizable, so they are rudimentary . There are 10 to 100 stamens in male flowers . The smooth ( Pandanus ) or papillary ( Freycinetia ) stamens are free or grown together in groups, often with "stemonophores". The basifixen dust bag consist of two counters with two pollen sacs . The two-celled pollen grains are furrowed or bumpy with an aperture and the pollen surface is often prickly. There are 1 to 80 free to fused carpels and sometimes staminodes in female flowers . Each upper carpel contains one to several anatropic ovules in basal or parietal placentation. There is at most a short stylus.
Fruits and seeds
When fruits are drupes ( Pandanus ) or berries ( Freycinetia ) formed. In some species the fruits are grouped together to form collective fruits, which are very differently structured, depending on the species. The fruits contain one to many tiny seeds. The endosperm can be starchy ( Freycinetia ) or oily ( Pandanus ) and fleshy. The basal embryo is tiny.
The number of chromosomes is n = 25, 28 or 30.
Systematics and distribution
The family Pandanaceae was first published in 1810 by Robert Brown under the name "Pandaneae" in Prodromus florae Novae Hollandiae et insulae Van-Diemen, exhibens characteres plantarum quas annis 1802-1805 per oras utriusque insulae collegit et descripsit Robertus Brown , p. 340. The type genus is Pandanus Parkinson .
The species of the family of the Freycinetiaceae Le Maout & Decaisne are assigned to the screw tree plants (Pandanaceae) today.
The Cyclanthaceae are a sister group of the Pandanaceae, these two families are most closely related to the Stemonaceae and Triuridaceae and within the order of the Pandanales the Pandanaceae are most distantly related to the Velloziaceae .
The family originated in the early to mid- Cretaceous period about 96 million years ago on the Gondwana continent when it broke up. There was a rapid adaptive radiation and this explains the current distribution of the genera. However, some species in Madagascar got there much later through long-distance distribution.
They have a distribution from the tropics to the warm temperate latitudes of the Old World . Their natural distribution areas are in tropical Central and West Africa , in Madagascar and nearby islands, from India to Thailand to China and from the Malay Archipelago to Australia to New Zealand and the Pacific Islands.
The family comprises only four genera with around 900 species:
- Freycinetia Gaudich. : With about 310 species. They are found in the tropics from Sri Lanka to the Pacific Marquesas Islands and Hawaii , in northern Australia and New Zealand . They usually grow as lianas and form berries.
Martellidendron (Pic. Serm.) Callm. & Chassot (Syn .: Pandanus subg. Martellidendron Pic. Serm. ): It is a relatively new genus that wasseparatedfrom Pandanus in2003. With about six types:
- Martellidendron androcephalanthos (Martelli) Callm. & Chassot : It occurs in northern Madagascar.
- Martellidendron cruciatum (Pic.Serm.) Callm. & Chassot : It occurs in eastern Madagascar.
- Martellidendron gallinarum (Callm.) Callm. : It occurs in eastern Madagascar.
- Martellidendron hornei (Balf.f.) Callm. & Chassot : It occurs in the Seychelles.
- Martellidendron karaka (Martelli) Callm. : It occurs in northern and eastern Madagascar.
- Martellidendron kariangense (Huynh) Callm. : It occurs in eastern Madagascar.
- Screw trees ( Pandanus Parkinson ): With eight subgenera and about 600 species. The screw trees produce stone fruits. They are common from the tropics and subtropics of the ancient world to the islands in the Pacific.
- Sararanga Hemsl. : It is the most original genus of the family with clearly recognizable three or four bracts. With only two tree-shaped species:
Some species of the screw tree family are used economically, for example Pandanus utilis, which is native to Madagascar . Flour is made from its fruits, and it is grown for fiber in the West Indies and Central America . An extract for perfume production is obtained from the Pandanus odorifer , which occurs in South Asia, Polynesia and Australia .
The bracts are used by some Freycinetia species and the fiber-rich leaves are used for weaving mats and baskets, binding material or for roofing.
- The Pandanaceae family on the AP website. (Sections Description and Systematics)
- The Pandanaceae family at DELTA by L. Watson & MJ Dallwitz. (Section description)
- Kun Sun, Robert A. DeFilipps: Pandanaceae , p. 127 - the same text online as the printed work , (PDF file; 93 kB) , In: Wu Zheng-yi, Peter H. Raven, Deyuan Hong (ed.): Flora of China , Volume 23 - Acoraceae through Cyperaceae , Science Press and Missouri Botanical Garden Press, Beijing and St. Louis, 2010, ISBN 978-1-930723-99-3 . (Sections Description and Distribution).
- Robert Brown: Prodromus florae Novae Hollandiae et insulae Van-Diemen, exhibens characteres plantarum quas annis 1802–1805 per oras utriusque insulae collegit et descripsit Robertus Brown. Robert Taylor, London 1810, p. 340, http: //vorlage_digitalisat.test/1%3Dhttp%3A%2F%2Fwww.biodiversitylibrary.org%2Fpage%2F2954496~GB%3D~IA%3D~MDZ%3D%0A~SZ%3D~ double-sided%3D~LT% 3D ~ PUR% 3D .
- Pandanaceae at Tropicos.org. Missouri Botanical Garden, St. Louis
- Pandanaceae in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved June 26, 2018.
- Rafaël Govaerts (Ed.): Pandanaceae. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved March 18, 2020.
- Martin W. Callmander, Philippe Chassot, Philippe Küpfer, Porter P. Lowry II: Recognition of Martellidendron, a new genus of Pandanaceae, and its biogeographic implications. In: Taxon Volume 52, No. 4, 2003, pp. 747-762, DOI: 10.2307 / 3647349 .
- Bryan A. Niedenberger, Anne Kadar Duzan: Family website. (engl.)