Bread palm ferns

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Bread palm ferns
Encephalartos ferox

Encephalartos ferox

Systematics
Class : Cycadopsida
Order : Cycads (Cycadales)
Family : Zamiaceae
Subfamily : Encephalartoideae
Tribe : Encephalarteae
Genre : Bread palm ferns
Scientific name
Encephalartus
Clay.

The encephalartos ( Encephalartos ) are a genus of flowering plants in the family of Zamiaceae within the order of cycads (Cycadales). The genus Encephalartos is restricted from distribution to Africa . All around 65 species of Encephalartos are threatened and are listed in Appendix I of the Washington Convention on Endangered Species (CITES).

description

Encephalartos barteri , illustration

The stem axis is formed underground or as an above-ground trunk. Underground it reaches a diameter of 15 centimeters. Tree-shaped trunks reach heights of up to 15 meters. The stems are cylindrical and pachycaul . Many species form additional shoots at the base of the trunk so that old plants can form a large clump. Otherwise branching is extremely rare.

The leaves are in a spiral arrangement at the end of the trunk. The cataphylls formed between the leaves are simply pinnate and very variable. The length ranges from 60 to 600 centimeters, the surface is dull to shiny, the color ranges from blue-gray to yellow-green to dark green. The rachis is curved inwards, straight or curved outwards to strongly bent back. The leaflets are often almost vertical from the rachis. They are narrow to wide, unreinforced or thorny. The lower leaflets are often completely transformed into thorns.

The female cones stand individually or up to eight on a plant. The size ranges from 30 cm long and 15 cm wide to 80 cm long and 40 cm wide. They are seated or stalked, erect or nodding. The color ranges from blue-gray to light and dark green to brown, chestnut brown, yellow, orange, pink and red. The surface of the cone can be smooth, pimply or wrinkled, bald to thickly hairy. The sporophylls are simple, fleshy, and have two (rarely three) orthotropic ovules on the adaxial side , the micropyle of which points towards the cone axis.

The male cones are more numerous than the female. The stems are usually longer than the female ones, otherwise the cones resemble the female ones. On each sporophyll there are numerous pollen sacs on the underside (abaxial). These open with slits. The pollen is boat-shaped (cymbiform) and has a germ fold (monosulcat).

The seeds are elongated to ellipsoidal, the sarcotesta is fleshy and red, yellow, orange or brown in color. The endosperm is habloid and is formed by the female gametophyte . The embryo has two cotyledons, which are usually connected at the tip, and a long, spiral suspensor . The germination extends kryptokotylar.

The number of chromosomes is 2n = 18.

Distribution map (labeled in English)

Distribution and locations

The genus bread palm ferns ( Encephalartos ) is restricted to Africa. The northern limit of their occurrence runs from Sudan via the Central African Republic, Nigeria to Ghana. In the south it occurs to South Africa. The focus is on eastern and southern Africa, with only Encephalartos barteri on the west coast .

The locations are extremely diverse, bread palm ferns grow in deserts, savannas and forests, but they are absent in rainforests. They occur at altitudes from sea level up to 2400 meters.

Systematics

The genus Encephalartos alone forms the Subtribus Encephalartinae , and together with the Subtribus Microzamiinae the tribe Encephalarteae . Up to 2002, about 63 species were distinguished within the genus; in the meantime other species ( Encephalartos flavistrobilus , Encephalartos mackenziei ) were added.

The types described so far are:

Botanical history

The genus Encephalartos was first described by the German botanist Johann Georg Christian Lehmann in 1834 . Before that, all cycads were grouped into the genus Zamia . The generic name Encephalartos means something like bread in the head and alludes to the use of the stem pulp as a starch supplier. Lehmann had also classified the Australian species of the family in the genus Encephalartos , which have now been transferred to their own genera Macrozamia and Lepidozamia .

use

Different types of Encephalartos were used to provide starch . Both the seeds and the pulp were processed into flour, mainly in times of need. The toxins were removed by repeated washing.

Several species of Encephalartos are used primarily in their natural range as ornamental plants in parks and gardens, especially in South Africa.

literature

Individual evidence

  1. Loran M. Whitelock: The Cycads. 2002. pp. 175-241.
  2. a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br bs Rafaël Govaerts (Ed.): Encephalartos. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved March 14, 2019.
  3. a b c d e Walter Erhardt among others: The great pikeperch. Encyclopedia of Plant Names . Volume 2, page 1387. Verlag Eugen Ulmer, Stuttgart 2008. ISBN 978-3-8001-5406-7
  4. ^ South African National Biodiversity Institute : Encephalartos woodii Sander . May 2002. Retrieved April 27, 2020.
  5. Novarum et Minus Cognitarum Stirpium Pugillus. Volume 6, 1834, p. 3. ( online )
  6. Entry on Encephalartos woodii at plantzafrica.com . (English)

Web links

Commons : Bread Palm Ferns  - Album with pictures, videos and audio files