Afrocarpus dawei
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Afrocarpus dawei is a plant from the genus of afrocarpus ( Afrocarpus ) in the family of podocarpaceae (Podocarpaceae). The natural distribution area is in Africa in Tanzania and Uganda , where the species grows in temporarily flooded swamp forests. The wood is used as construction timber and for carpentry work.
description
Appearance
Afrocarpus dawei grows as an evergreen tree and reaches heights of up to 33 meters. The long trunk reaches chest height diameters of up to 100 centimeters. The trunk bark is dark brown, gray when exposed to the weather and smooth in young trees. In large trees it flakes off in small round or rectangular scales. The branches are rising and spread out and form a small, flat crown. The leaves grow close to numerous branches. Young side branches are more or less square and grooved in cross section.
Buds and leaves
Terminal buds are relatively small, about 2 millimeters in diameter and can also be missing. The bud scales are triangular or rounded, the tip can be beaked.
The leaves of seedlings and young plant specimens are mostly opposite and are narrow, linear-lanceolate, up to 17 centimeters long and 4 to 8 millimeters wide, straight or crescent-shaped and tapering to a thin point. Leaves of adult specimens are shorter, only from 2 usually 3 to 5 and sometimes up to 6 centimeters long and from 1.5 usually 2 to 4 and sometimes up to 5 millimeters wide. The leaves are arranged in a spiral and are spread or ascending. They are twisted at the narrowed base so that the adaxial side points downwards, gray-green, straight or only slightly crescent-shaped, linear-elliptical to linear, and converge abruptly or slowly after three quarters of the length towards the pointed upper end. The adaxial side has a clearly protruding central rib. Numerous interrupted stomata lines are formed on both sides of the leaves , which are only indistinctly separated by the midrib.
Cones and seeds
The pollen cones grow individually or in twos or threes on short stalks or almost sitting, often in the leaf axils together with several paper-like bracts . The pollen cones are initially round, later elongate and are cylindrical when ripe, 10 to 20 rarely up to 25 millimeters long with a diameter of 2.5 to 3.5 millimeters. The microsporophylls are arranged in a spiral, triangular to diamond-shaped, about 1 millimeter wide and have a toothed-bitten edge and a pointed or pointed end. Two round pollen sacs are formed for each sporophyll .
The seed cones grow individually on narrow, scaly or leafy branches in or under the leaf axils. They consist of several sterile and one larger, terminal and fertile cover scale. Mature seed cones have a single seed that grows opposite a single, small cover scale. The seed is surrounded by a firm, fleshy epimatium that changes color from green to glaucous green and, when ripe, to yellow. It is then round and 25 to 35 millimeters long. The actual seed is egg-shaped and laterally slightly flattened, 16 to 21 millimeters long and 12 to 15 millimeters wide. The surface is wrinkled and hard, the seed coat 2 to 4 millimeters thick.
Distribution and ecology
The natural range is in Tanzania in the provinces of Kagera and Mara and in Uganda. There, Afrocarpus dawei and other species are the dominant tree species during the rainy season of flooded swamp forests, which are located on slowly flowing streams east and south of Lake Victoria at altitudes of 1,100 to 1,200 meters. The species is most often found together with Baikiaea minor and species of the genus Mimusops .
Hazard and protection
Afrocarpus dawei was classified by the IUCN in the Red List in 2011 as "potentially endangered" = "Near Threatened". The range of occurrence ("extent of occurrence") with about 175,000 square kilometers and the stocks, which exist on about 3200 square kilometers, are both too large to derive a risk from it, and the influence of the people in the distribution area is only slight. However, it appears to have resulted in a decrease in stocks, which is estimated at over 20 percent.
Systematics and Etymology
The first description was in 1917 under the name ( Basionym ) Podocarpus dawei by Otto Stapf in the Flora of Tropical Africa , Volume 6, page 342. The new combination to Afrocarpus dawei (Stapf) CNPage was 1989 by Christopher Nigel Page in the Notes from the Royal Botanic Published Garden, Edinburgh , Volume 45, page 384. Further synonyms for Afrocarpus dawei (Stapf) CNPage are: Afrocarpus mannii subsp. dawei (Stapf) Silba , Nageia mannii var. dawei (Stapf) Silba , Podocarpus usambarensis var. dawei (Stapf) Melville .
Afrocarpus dawei is a kind from the genus of afrocarpus Afrocarpus within the family Podocarpaceae . James Eckenwalder sees the differences to Afrocarpus falcatus as insufficient and the transitions as too continuous to give the specimens species status. He therefore sees the name Afrocarpus dawei only as a synonym for Afrocarpus falcatus .
The generic name Afrocarpus is derived from the Latin afro for "African" and carpus for "fruit". The name was given to the genus to distinguish it from the name of the genus Podocarpus , from which it was separated. The specific epithet dawei honors the botanist Morley Thomas Dawe (1880–1943) who found the type specimen .
use
The wood from Afrocarpus dawei is of high quality, the trunks are very large and only form branches at great heights. It is used as lumber and for carpentry work. Despite the sometimes difficult accessibility of the areas, the trees are selected and felled individually. However, the wood is not exported, but processed regionally. The species is not cultivated.
swell
literature
- Aljos Farjon: A Handbook of the World's Conifers . tape 1 . Brill, Leiden-Boston 2010, ISBN 978-90-04-17718-5 , pp. 136-138 .
- James E. Eckenwalder: Conifers of the World. The Complete Reference . Timber Press, Portland, OR / London 2009, ISBN 978-0-88192-974-4 , pp. 126, 127 .
Individual evidence
- ↑ a b c d e f Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 137.
- ↑ Afrocarpus dawei in the endangered Red List species the IUCN 2013. Posted by: A. Farjon, 2011. Accessed February 7, 2014.
- ↑ a b Afrocarpus dawei at Tropicos.org. Missouri Botanical Garden, St. Louis, Retrieved May 18, 2019.
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↑
- Christopher J. Earle: Afrocarpus dawei. In: The Gymnosperm Database. www.conifers.org, November 23, 2012, accessed February 7, 2014 .
- ↑ James E. Eckenwalder: Conifers of the World , p. 127.
- ^ A b Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 136.
- ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 138.