Solanum viarum
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Solanum viarum |
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Solanum viarum is a plant type from the genus of Solanaceae ( Solanum ). Within the genus, it is classified in the subgenus Leptostemonum , which is mainly characterized by the conspicuous spines. Solanum viarum is consideredan invasive weed in the southeastern United States and Australia .
description
Vegetative characteristics
Solanum viarum is an upright shrub 0.5 to 2 m high with a large number of splaying branches. The shoots are covered with uniform, simple, glandular trichomes that are 0.4-0.5 mm in length. The plant is weakly covered with spines . The longest spines reach a length of 8 mm, are bent back and strongly broadened at the base, while the shorter ones are often only 1 mm long and rather thin, straight and splaying. The base of the spines is covered with short, fine trichomes with glandular tips, as well as with somewhat longer, pointed trichomes with a length of up to 0.2 mm.
A sympodial unit consists of two leaves that are usually arranged in pairs. One leaf is about twice as large as the second, the larger ones have a leaf area of 7 to 10 (15) × 6 to 8 (15) cm and are usually as long as they are wide. The petioles of the larger leaves are 3 to 6 cm long. The thin leaves are ovate to almost circular, the base of the leaves is heart-shaped to blunt. The leaf margin usually has three to five pairs of blunt or pointed lobes, which in turn can be entire or lobed. The tip of the leaf is pointed or blunt. On the side facing the axis, they are hairy with two- to three-cell, translucent, 0.4 to 1 mm long trichomes. The side facing away from the axis is densely covered with simple, glandular, about 0.4 mm long trichomes, but there are also slightly longer, simple, translucent trichomes up to 0.8 mm in length and sessile four- (rarely five) -radiated, star-shaped trichomes with one Diameter of 0.8 to 1 mm and a height of 0.5 to 0.8 mm. The leaf stalks are covered with trichomes similar to those found on the shoot, but there are also some simple, three-cell, translucent trichomes up to 1.2 mm in length. Both sides of the leaf are sparsely covered with spines, these vary from straight, needle-like spines to very fine spines that sit on the thinner leaf veins. The spines on the petioles are needle-shaped and 5 to 18 mm longer than those on the shoot.
Inflorescences and flowers
Solanum viarum blooms all year, but strengthened in the period from September to April. The inflorescences standing outside the leaf axils are sessile or almost sessile, are unbranched and consist of three to five flowers . Usually only the lowest flower, rarely the lowest two flowers, is fertile. The axes of the inflorescences are densely haired with simple, glandular trichomes with a length of 0.4 to 0.6 mm, in between there are individual simple, translucent trichomes that can be up to 1.2 mm long. There are either no spines on the inflorescence stalks or there are only a few, up to 2 mm long. The flower stalks, which are wound around the shoot and lie close to the inflorescence axis, are 7 to 11 mm long during flowering, and when the fruit is ripe they have enlarged to 10 to 21 mm. The cross-section of the flower stalks is round, the diameter is 2 mm, towards the tip it is hardly enlarged.
The flowers have a 3 to 4 mm long, triangular calyx , the tube 2 mm and the pointed lobes 0.8 to 2 mm long. At the base it is about 0.6 to 0.8 mm wide. The hairiness is similar to that of the flower stalks, but the number of simple, transparent trichomes is usually slightly higher. The calyx is not bristled or only has a few trichomes up to 2 mm long. The calyx is enlarged on the fruit, the calyx lobes are 4 to 6.5 mm long and 3.2 to 4 mm wide at the base. The greenish or whitish crown is very delicate, has a diameter of about 2 cm, is 10 to 13 mm long and star-shaped. The corolla tube is 2 to 3 mm long, the narrowly lanceolate corolla lobes 7 to 10 mm long and at the base 2.5 to 3 mm wide, tapering towards the tip. The outside is covered with simple, glandular trichomes up to 0.6 mm long, the inside is hairless. The stamens consist of a 1 to 1.8 mm long filament, on which a light yellow to cream-colored, 5.5 to 6.9 mm long and at the base 1 to 1.5 mm wide anthers freely stands, which is pointed to the front and opens there with small pores. The ovary is densely hairy with simple, pointed trichomes that are between 0.2 and 0.35 mm long, with a few shorter, glandular hairs in between. When the ovary enlarges, the hair falls off, and when the ovary reaches a diameter of about 5 mm, there are no more trichomes. The pistil of the fertile flowers is 6.8 to 8.2 mm long, 0.5 mm in diameter, cylindrical and hairless, the stigma is head-shaped.
Fruits and seeds
The fruits are spherical berries with a diameter of 2.2 to 2.5 cm. When unripe the fruits are light green with dark green spots, when ripe they turn yellow. Inside there is an approximately 5 mm thick, whitish or greenish mesocarp with a spongy consistency. Per fruit there are between 190 and 385 light red-brown seeds that are flat, kidney-shaped and 2.2 to 2.8 × 2.0 to 2.5 mm in size.
Chromosome number
The number of chromosomes is 2n = 24.
Distribution and habitat
The original distribution area of the species ranges from Paraguay to northeast Argentina and Uruguay to large parts of eastern Brazil . There the plants grow mainly on pastures, on roads, on garbage dumps, cultivated areas and on the edge of forests in low altitudes, usually below 1000 m. The species can now be found in India , Africa , China , Vietnam , Australia , Central America and the West Indies , and has been spreading in the southeastern United States since the 1980s, where it is considered a dangerous, invasive weed .
Systematics
Solanum viarum is classified in an unnamed series of the subgenus Leptostemonum , section Acanthophora . In addition to Solanum viarum, this series consists of the species Solanum myriacanthum, which occurs in Mexico and northern Central America , and the species Solanum aculeatissiumum, which can be found in Brazil, Africa and the Indian subcontinent . The cladistic relationships of three species of this monophyletic series have not yet been determined beyond all doubt.
meaning
Solanum viarum is considered an invasive weed in many of the areas where the species was introduced. Due to the prickly leaves and stems, the plant is not of interest to livestock as a forage plant, so that it grows into dense, impenetrable thickets. The fruits, however, are eaten by cattle and smaller mammals, so that this promotes further spread in the area. Especially in areas of central and southern Texas , the species has covered large areas of pasture, so that these are no longer suitable as standing areas for livestock. Estimates of the affected areas are 400,000 to 500,000 hectares for the state of Florida in 1995 and 1996, respectively. Herbicides or plowing are often used against the species, but often only with limited success. In 1994, a program to combat the spread of the species was started in the United States. For this purpose, natural predators from Brazil, Paraguay and Argentina were searched for, with which the spread can be contained. For this reason the leaf beetle (Coleoptera) Gratiana boliviana was introduced in Florida in 2003 , the larvae and adult specimens of which feed on the plants. In some cases, a decline in Solanum viarum populations of up to 90% could already be determined within three years , but the species could not be completely contained in this way. In a 2006 survey, 80% of Florida's cattle farmers surveyed said the species was found on their pastures, and over 65% identified it as a serious problem in raising livestock. Overall, the losses that the cattle farmers of Florida in 2006 by the way came to 15 million were US dollar appreciated. In addition to cattle breeding, the cultivation of plants is also impaired by the spread of the species, as they are carriers or host plants for pests and diseases of economically important nightshade plants such as tomatoes ( Solanum lycopersicum ), peppers ( Capsicum ), eggplant ( Solanum melongena ) and tobacco ( Nicotiana tabacum ) can be.
swell
- ↑ Department of Agriculture and Fisheries, Biosecurity Queensland [1] , Online, accessed on 21 August 2017th
- ↑ a b c d e f PBI Solanum: Solanum viarum , Online, accessed October 1, 2007.
- ↑ Solanum viarum at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ↑ a b c d Rodrigo Diaz et al .: Biology and Host Specificity of Anthonomus tenebrosus (Coleoptera: Curculionidae): A Herbivore of Tropical Soda Apple. In: Annals of the Entomological Society of America , Volume 106, Number 4, 2013. Pages 491-502. doi : 10.1603 / AN13020
- ^ Rachel A. Levin, Kimberly Watson and Lynn Bohs: A four-gene study of the evolutionary relationships in Solanum section Acanthophora . In: American Journal of Botany , Volume 92, Number 4, 2005. Pages 603-612.
- ↑ a b c Tajudeen Salaudeen et al .: Economic Impact of Tropical Soda Apple (Solanum viarum) on Florida Cattle Production. In: Weed Technology , Volume 27, Number 2, 2013. Pages 389-394. doi : 10.1614 / WT-D-12-00027.1
