Nicotiana africana
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Nicotiana africana is a plant type from the genus tobacco ( Nicotiana ). It is the only species of the genus thatis nativeto Africa . Within the genus it is the only found in Australia occurring section Suaveolentes classified.
description
Vegetative characteristics
Nicotiana africana is a perennial , bushy, branched plant that grows up to 2.5 meters high and is slightly woody at the base. The entire plant is densely hairy with glandular trichomes . The stems reach a diameter of up to 2 centimeters, their hair consists of little to multicellular trichomes, the tip of which always consists of a single cell. The native foliage leaves wither relatively early, on the stems the leaves are growing closer and closer to the tip, but become smaller in the process. The shape of the leaf blade of the stem leaves ranges from ovoid to elliptical or obovate in the case of the upper leaves, it becomes 20 to 38 centimeters long and 8 to 18 centimeters wide. The base is drawn together to form broad wings that run down a short stem and half enclose it with two auricles, but less noticeable on the upper leaves. The leaf blade is round towards the tip. The leaf margin is predominantly whole, towards the base it can often be slightly wavy. The leaf surfaces are also covered with glandular trichomes that have single-celled tips, and hydathodes are sparse .
Inflorescences and flowers
The flowers are in narrow cylindrical thyrs , several of which sometimes form a sparse overall inflorescence . The side branches are double wraps or wraps of (rarely only one) five to ten flowers, which are mainly at the tips of the inflorescences. In cultivated specimens, partial inflorescences can be formed from up to 25 flowers. The flowers are on 7 to 15 (rarely up to 21) millimeter long, glandular hairy pedicels .
The flowers themselves are 3 to 4 centimeters long, have dense glandular hairs on the outside, slightly zygomorphic and do not close even in sunshine. The calyx is cylindrical, 10 to 13 (rarely up to 15) millimeters long and has triangular, blunt and somewhat unevenly shaped calyx tips. These are about 1/3 as long as the chalice. The basal part of the crown is 9 to 11 millimeters long and measures 3 to 4 millimeters. In the area covered by the chalice, five slightly deepened, whitish longitudinal grooves are formed. The front part of the corolla tube is 23 to 29 millimeters long and widens from 4 to 5 to 6 to 7 millimeters in diameter. The outside of the curved corolla tube is light green and covered with trichomes with glandular, multicellular heads. The inside is whitish green and hairless. The coronary hem sits crooked on the corolla tube, is colored white and measures 6 to 7 millimeters. It is weak, lobed to about 1/3 of the width with outstretched lobes. The border of the flowers is strongly and irregularly bent back.
The five stamens protrude 10 to 12 (rarely 9 to 16) millimeters from the corolla tube. They come in three different lengths: one pair is long, a second pair is medium in length, and the single remaining stamen is the shortest. The starting points of the stamens are also at three slightly different heights at the base of the front part of the corolla tube, where the stamens are also hairy somewhat downy. The stylus is similar in length to the stamens and is S-shaped in the lower third.
Fruits and seeds
The fruit is a broad, egg-shaped capsule that is 11 to 14 millimeters long and either as long as the calyx or just protrudes slightly above it. The capsule opens with four flaps. The dark brown seeds are 0.7 to 0.9 millimeters long, are obliquely conical to pyramidal and have a net-like surface made of irregularly curved ribs.
Chromosome number
The number of chromosomes is 2n = 46.
Distribution and locations
The species is widespread in the Middle Namib and occurs there in isolated granite stocks.
Systematics
Within the genus Nicotiana , Nicotiana africana is classified in the section Suaveolentes . Molecular biological investigations could show that the species probably separated from the Australian-based representatives of the section early on and is to be regarded as the sister taxon of the rest of the section.
Research history
A specimen of Nicotiana africana was first collected in 1965 on the Omandumba-West Farm and placed in the collection of the Herbarium in Windhoek . A duplicate of the herbarium evidence went to the Botanical State Collection in Munich . Since the genus Nicotiana was not considered to be native to Africa, no great attention was paid to the specimen, as it was assumed that it was a cultivated, feral or dragged plant. Nonetheless, some of the seeds were cultivated in the Munich-Nymphenburg Botanical Garden . It turned out that the plant could not be assigned to any of the known Nicotiana species, so more detailed investigations began. This enabled further locations of the species to be identified in Namibia, and morphological and karyological analyzes were also carried out. It was not until 1975, when it could be ruled out that it was a hybrid species and that it was found in Namibia in the natural habitat of the plant, that Hermann Merxmüller published the first description of the new species in the "Mitteilungen der Botanische Staatssammlung München".
Hazards and protective measures
Although this species has only a limited range, no specific threats are known, so the IUCN classifies this species as Least Concern .
proof
- ↑ Nicotiana africana at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ↑ James J. Clarkson et al .: Phylogenetic relationships in Nicotiana (Solanaceae) inferred from multiple plastid DNA regions . In: Molecular Phylogenetics and Evolution , Volume 33, 2004. pp. 75-90. doi : 10.1016 / j.ympev.2004.05.002
- ↑ H. Merxmüller and KP Buttler: Nicotiana in the African Namib - a botanical and phylogenetic riddle. In: Mitteilungen der Botanische Staatssammlung München , Volume 12, December 15, 1975. pp. 91-103.
- ↑ Nicotiana africana in the IUCN Red List of Threatened Species 2013.2. Posted by: Craven, P., 2004. Retrieved May 18, 2014.