Microcycas calocoma
| Microcycas calocoma | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Microcycas calocoma |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name of the genus | ||||||||||||
| Microcycas | ||||||||||||
| (Miq.) A.DC. | ||||||||||||
| Scientific name of the species | ||||||||||||
| Microcycas calocoma | ||||||||||||
| ( Miq. ) A.DC. |
Microcycas calocoma , also called dwarf palm fern, is the only species of the plant genus Microcycas in the family of the Zamiaceae within the cycads (Cycadophyta).
description
Vegetative characteristics
Microcycas calocoma is a very long-lived, evergreen, tree-shaped plant that can grow to heights of over 10 meters; this species is one of the species with the greatest heights among the cycads.
The leaves are simply pinnate fronds that look very similar to fern fronds . Unlike the similar palm fronds , the leaf veins in the cycads are forked ( dichotomous ). Most of the time, a wreath of new leaves forms at the same time, usually once a year. The older the plant, the more new leaves are formed each year. The tough leaf fronds are 0.6 to 1.2 meters long with 50 to 80 pairs of pinnate leaves. The leaflets in the central area are 15 to 25 inches long and 0.8 to 1.0 inches wide.
The trunks of cycads are mostly (apparently) unbranched, but very old specimens can simply be branched. Only with the formation of fertile leaves ( sporophylls ) does it come to branching at the base of the fertile sections, because the cones are actually special shoot sections. After the seed has formed, the cones are pushed aside by a side bud.
Generative characteristics
Microcycas calocoma is dioeciously segregated, so there are both male and female individuals ( diocyte ). In the Zamiaceae family, the plants of both sexes have cone-shaped inflorescences. The short (2 to 4 centimeters long) stalked male cones are yellowish brown and cylindrical with a length of 25 to 30 centimeters and a diameter of 5 to 8 centimeters. The short (2 to 4 centimeters long) stalked female cones are yellowish-brown and cylindrical with a length of 50 to 90 centimeters and a diameter of 13 to 16 centimeters. The pink to red seeds are egg-shaped with a length of 3.5 to 4 centimeters and a diameter of 2 to 2.5 centimeters.
The number of chromosomes is 2n = 26.
ecology
Microcycas calocoma has the largest egg cell (500 to 600 µm) in the plant kingdom. When the pollen reaches the female ovule on the mega sporophyll , the generative cell divides into a stem cell, which remains on the prothallium cell, and a so-called "spermatogenic cell". The spermatogenic cell then only forms up to about 20 spermatozoids in Microcycas calocoma (in all other plants there are much fewer), which are enclosed by the pollen tube cell . The spermatozoids are also quite large at 300 (up to 500) µm. This feature is very original. The spermatozoids swim to the egg cells with a helically wound hostage tape. Several months pass between pollination and fertilization .
Occurrence
Microcycas calocoma is endemic to several small areas in western Cuba , just in the province of Pinar del Río . Most of the specimens grow in the area of the hill karst areas ("Low Mogotes") in a semi-evergreen forest, but they are not closely tied to specific locations.
Most of the specimens have a registration number on the trunk. It is an endangered species.
Systematics
The first description of this species was in 1852 under the name ( Basionym ) Zamia calocoma by Friedrich Anton Wilhelm Miquel in Flore des serres et des jardins de l'Europe , Volume 7, page 141. The genus Microcycas was in 1868 by Alphonse Louis Pierre Pyrame de Candolle in Prodromus Systematis Naturalis Regni Vegetabilis , 16, 2, page 538 with the type species Microcycas calocoma (Miq.) A.DC. set up.
etymology
In Cuba this type of plant is called “Palma corcho”, this has been translated into cork oak in some German-language travel guides (misleading). The botanical name calocoma is derived from the Greek calos for beautiful and coma for hair; Microcycas means something like small species of Cycadophyta, but it is one of the largest modern species.
literature
- David L. Jones : Cycads of the World. Ancient Plants in Today's Landscape. 2nd edition. Smithsonian Institution Press, Washington DC 2002, ISBN 1-58834-043-0 .
Individual evidence
- ↑ Microcycas calocoma at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ^ Peter Sitte , Hubert Ziegler , Friedrich Ehrendorfer , Andreas Bresinsky : Strasburger . Textbook of botany for universities. 34th edition. Gustav Fischer, Stuttgart et al. 1998, ISBN 3-4372-5500-2 , p. 711 ff.
- ↑ Microcycas at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed March 15, 2019.
- ↑ Rafaël Govaerts (ed.): Microcycas. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved March 15, 2019.
Web links
- Microcycas calocoma at The Cycad Pages of the Royal Botanic Gardens Sydney.
- Microcycas calocoma in the endangered Red List species the IUCN 2018 Posted by: JD Bösenberg, 2009. Accessed on March 15 of 2019.
- Profile at the Botanical Garden in Tübingen.