Chigua

Chigua is a genus of cycads ( Cycadales ) with only two species, both are listed on Appendix I of the CITES Convention ( CITES). The genus is endemic to Colombia.

Features

The stems grow underground, are bulbous and elliptical. Each plant has a single bulb, which measures up to 10 inches in diameter. Branching is rare. The petiole is busy nearly cylindrical and with numerous short spines, the major axis of the leaves ( rachis ) is semi-cylindrical and also the thorny approach towards short.

The usually two to five leaves per plant are simple feathery, 1 to 2 m long and with stipules. The leaflets are sessile, hairless papers and wedge-shaped at the base. The approach to the sheet located toward leaflets are alternate, the middle nearly opposite, the extreme opposite sides. Your middle ribs are clearly highlighted, the side fins are branched dichotomously. The Lower leaves are triangular, they also have stipules.

The male cones are cylindrical and filled with brown - red hair, the stem is hairless. The microsporophyll is approximately umbrella-shaped, hexagonal tip is sterile. The female cones have a longer stalk than the male cones, which gradually merges into the base of the pin and is hairless. The pins are cylindrical. the Megasporophyll is umbrella -shaped, the sterile tips are hexagonal, with a hump in every corner. The seeds are oval and mature red.

Dissemination and locations

The known species occur in Colombia before the Department of Córdoba. They grow in moist rainforest in altitudes of 75 to 200 m. Chigua is threatened as a result of dam projects with extinction because of the dam would flood the entire known area.

Botanical history and systematics

The genus was first described in 1990 as far last cycad genus, the genus name is the common names, the types of Zamiaceae be designated by the Colombian Pacific Coast. First specimens were discovered in 1918 by Francis Pennell and then placed in the genus Zamia, the material consisted only of a sheet and a part of an unbranched tuber.

In the 1980s, Sergio Sabato recognized during a revision of the genus Zamia the particular features such as clear midrib of the leaflets that are not otherwise found in Zamia. For expeditions in 1986 and 1987 several specimens were of two different types found by Rodrigo Bernal. About the outsourcing of these two species in a separate genus, there were different opinions. Isozyme analysis indicated about out that they belong to Zamia. Also biogeographic and phylogenetic studies confirm this close to the Zamia The question is not currently decided to Stevenson should only provide information on a comprehensive molecular genetic analysis of the neotropical cycads whether Chigua are part of Zamia or not. The question of whether there are two or only one type is open, as a diagnostic feature used so far only the shape of the middle leaves.

The two types are:

  • Chigua bernalii
  • Chigua restrepoi

Documents

  • Loran M. Whitelock: The Cycads. Timber Press, Portland, OR 2002, ISBN 0-88192-522-5, pp. 77 ff
  • Dennis Wm Stevenson: Cycadales ( = Flora de Colombia Vol 21, ISSN 0120-4351. ). Universidad Nacional de Colombia, Bogotá 2001, pp. 23-25 ​​.
  • Cycads
  • Cycadopsida
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