Solanum
Potato ( Solanum tuberosum)
Nightshade (Solanum ) is a genus in the family of nightshade (Solanaceae ). The genus contains about 1400 species. In general, there are herbaceous plants, to creeping, sometimes grow upright and trailing. In the tropics there are also woody species: shrubs and even up to 20 m high trees.
Major crops of the genus are the potato ( Solanum tuberosum), the eggplant (Solanum melongena ) and tomato ( Solanum lycopersicum ), but there are still a number of other species that have medicinal or ornamental plant relevance to humans as food. Many nightshade are toxic to humans or have poisonous parts. Cause are usually several alkaloids.
Among other things, due to the size of the genus, the system is still very uncertain. For example, the tomato and tamarillo were filed long time in the separate genus Lycopersicon or Cyphomandra, currently these groups of the genus Solanum are subordinate.
- 4.1 Internal systematics
Description
Vegetative characteristics
Solanum species are short-lived or perennial herbaceous plants or woody plants that grow as shrubs, vines or trees and can grow up to 20 m high, or are prostrate or climbing. The shoot axis has a sympodiales branching scheme on, that is, the stem axis divides during growth continues in addition to step on. There are streamers, rhizome, tuber- brut or bodying agents. Some of the shoots have sting or are hairy with trichomes. The latter can be very diverse, there are simple, glandular, star-shaped, tree -like or urchin -like branched forms. The spines are usually on the rungs to find the leaves or on the calyx, they can be straight or bent back, be provided thin and needle-like, or even with a broadened base. The leaves are simple or compound, bestielt or more rarely sessile. The leaf margin is entire, toothed, lobed or sinuate. The leaves of all solanaceous species are alternate, often, however, the leaf objects appear opposite or in pairs, which can be caused by complex growth schemes.
Flowers and inflorescences
The inflorescences arise terminally, in the branch axils, the leaves opposite or outside of branches. They form dichotomous branching or uniaxial, occasionally winding -like umbels of two to ten, rarely to 20, but also up to 300 flowers. They are often arranged in racemose or doldenrispig, in many species, the inflorescences, however, are reduced to simple, racemose, then input structures.
The flowers are mostly small, are rarely alone, nearly sessile or short-stalked, occasionally zygomorphic (mono balanced). Unisexual flowers are very rare, usually then stand at the base of the inflorescence fully hermaphroditic flowers, while the outer flowers have only male reproductive organs, dioecious occurs only in exceptional cases. The perianth is usually fünfzählig, but occasionally four -, six- or zehnzählig. The bell-shaped calyx consists of five calyx lobes or segments that increase in part after the flowering stage. The corolla is white, green, yellow, pink or purple colored, it lacks the inner ring of trichomes, it is wheel-shaped, broadly bell-shaped, wheel-shaped or star-shaped. Clean bell-shaped crowns as in Solanum fiebrigii are only known from very few species. The corolla tube is very short, the hem is fünfwinkelig, strongly divided or slightly lobed, the lobes or segments are projecting or reflexed. The fertilization of flowers mainly by pollen-collecting bees.
The five stamens are usually the same length, but sometimes also occur stamens of different length within a flower, then a stamen is longer than the other four. The stamens are generally much shorter than the anthers, rarely they are the same length or even longer. The stamens are divided usually into two sectors: the basal part is fused with the corresponding parts of adjacent stamens and complete with the corolla tube, which is distant from the base usually slightly shorter than the first part, is occasionally free, but can also grown together with the adjacent parts, so that a 0.2 to 1.5 mm wide ring is formed. The anthers are partially tapered towards the top, sometimes at the top slightly wider than at the base. You may be inclined to each other or not, in exceptional cases, they are partially or completely fused together. They usually jump starting of holes or full of holes from above along the longitudinal axis, partially follows a crack along the longitudinal axis, which may be short, but can also reach the base of the dust bag. Notwithstanding this scheme, the species of section Lycopersicum are (the former genus of tomatoes), which jump the anthers with longitudinal cracks. The pollen grains are usually threefold, in some ways a part is also vierfaltig, the outer layer of the pollen grain wall is granular. In the cases in which dioecious occurs, the pollen is formed in the female flowers, aperturlos. The size of the pollen grains is usually small ( 10 to 25 microns ), less often medium sized (25 to 28 ( 30) microns ) and, in exceptional cases, larger (41 to 45 microns ).
The female flower parts consist of two carpels, the ovary is zweikammerig, the nectaries are lacking. The stylus is busy glabrous or with trichomes, enlarged straight or curved, cylindrical or in the basal 2/3, rarely vice versa pfriemförmig. In some of the species is the pen of dimorphic, there are then simultaneously flowers with short and long pistils. The scar is spherical and not flattened, saddle-shaped or disc-shaped and non- flattened.
Fruits
The fruits are berries with juicy, slimy or fleshy pericarp, with or without stone cells, some of which there are deviations, then the fruit can be woody or dry, jumping up and to the capsule fruit becoming. The shape of the berries is usually more or less spherical, ( 5) 9-20 (35 ) mm in diameter, but in some cases even larger. The calyx persists on the fruit, bends partly and / or increases. Usually located in a fruit about 20 to 80 seeds, there are also types of up to 1600 to 1800 seeds per fruit. The seeds are disc-or kidney-shaped, strongly pressed, 1.2 to 4 (rarely to 7 or 8 ) mm long, usually slightly pitted. The embryo is highly helical, the cotyledons are shorter than the remainder of the embryo the endosperm is richly marked.
Distribution and habitats
The Nightshade have worldwide distribution with the exception of areas near the North Pole. Diversity and Endemismuszentren lie mainly in the Andes as well as in North America and Mexico, Central America, the eastern Brazil, the Caribbean, Australia, Africa and Madagascar.
Within this distribution areas of the nightshade have adapted to a large number of different habitats. They come in altitudes from 0 to 4500 m before and also populate areas with extreme environmental conditions such as deserts and rainforests.
Chromosome number
Due to the size of the species and of unclear systematics there is still no complete study of the chromosome number within the genus. However, most of the studied species have a base chromosome number of, so. Polyploidy is very common, so there are representatives of sets of chromosomes, and. Exceptions are seven known species of the Australian section Archaesolanum with, Solanum bullatum with and Kuheuterpflanze with.
System
Inside systematics
The most widely used classification based on morphological characteristics, is the 1972 by William D' Arcy established in 1991 and expanded system. He divided the genus into the following seven sub- genres. These subgenera were first divided by him in 52, in the enlarged system in 64 sections. Armando Hunziker cites in his 2001 work "The Genera of Solanaceae " on the scheme D' Arcy's 1972, but does not due to recent morphological work, all sections, and assigns other to within the genus. In the case of the subgenus Leptostemonum Hunziker discusses the classifications of D' Arcy (22 sections), Whalen (33 groups) and Nee ( 10 sections ), but without committing to a separate classification. The following table shows the classification of the genus according to the state Hunziker.
Without classification in one of the classes remain the sections Herpystichum, Herposolanum, Cyphomandropsis and Regmandra by Hunziker. The Normania described by D' Arcy as a section obtained by Hunziker again the status of a separate genus.
A phylogenetic analysis based on ndhF data from 115 Solanum species by Lynn Bohs showed that some of the subgenera used by D' Arcy are not monophyletic. According to their results, the genus Solanum can be divided into twelve major clades. In contrast to the D' Arcy's systematics tomato (Lycopersicon ), Tamarillo ( Cyphomandra ) Normania and Triguera are here considered as sections within the genus Solanum.
A final classification can not be set up due to these studies, since not only the relationships among the clades are not uniquely determine by the results and the results should be confirmed on the other by appropriate investigations of other genes as well as morphological and biochemical properties.
Botanical history
The first description of the genus was made in 1753 by Carl Linnaeus in his work Species Plantarum, he listed a total of 23 species under the genus name Solanum, mainly European and American species. Among other things, he took it to the works of Dillenius from the reference year 1732. In the following years, the number of species that have been assigned to this genus, is steadily increasing. In the 1813 paper published in Michel Félix Dunals Histoire naturelle, médicale et économique of Solanum et des genres qui ont été Confundus avec eux total of 235 species were distinguished, in the revised version of 1816 already 321 For issued by Alphonse Pyrame de Candolle Prodromus systematis naturalis regni vegetabilis wrote Dunal to 1852, a comprehensive monograph of the genus with a circumference of about 900 species. The genera Lycopersicon and Cyphomandra that are now counted as sections Lycopersicum or pachyphylla to the genus Solanum, he led in this work as separate genera.
Dunal shared the nightshade initially into two groups, Inermia for species with spines and Aculeata for species without spines. Until 1852, he developed it into a first approach to divide the genus into sections, which also noticed other morphological features such as the shape of the dust bag. A further subdivision presented Georg Bitter 1919 before, but was referring to the same features as Dunal.
However, the 1962 presented distinction of the genus by Almuth Seithe did not refer dust bag and spikes, but solely on the morphology of trichomes. This system was extended in 1970 by S. Danert to features of the branching scheme of the shoot axis and the shoot. All these features formed the basis for the systematics of the genus, which was erected in 1972 by William D' Arcy and the genus is divided into seven sub- genres, which for a long time represented the most commonly used system. D' Arcy expanded its system in 1991 to more sections and named it one section at. Further approaches to subdivision of the genus presented 1999 Michael Nee (but only for species of the New World ) and 2001 A. Child and RN Lester ago. Armando Hunziker cites in his book published in 2001, The Genera of Solanaceae on the classification by D' Arcy with the level of 1972, but makes minor changes to include more recent scientific findings in the division. While most works list characteristics or the characteristic species of the subgenera, sections and series, a complete list of species included is established only by Nee. Thus, a comparison of the different work is very difficult.
Despite intensive research on the genus not a complete description of this genus has been published up to the species level since Dunals publication in 1852. Since 2004, research groups are working under the direction of Lynn Bohs ( University of Utah ), Sandra Knapp ( Natural History Museum, London ), Michael Nee (New York Botanical Garden) and David Spooner ( University of Wisconsin ) on a new, full monograph of the genus. It will support the joint project by the U.S. National Science Foundation. An important result of this work is the 2005 by Lynn Bohs and 2007 by Terri Lynn Weese and Bohs established subdivision cladistic point of view, describing a total of 13 major clades within the genus.
Origin of the name
The name Solanum is derived from the Old High German or Middle High German nahtscato seam chats. For the interpretation of the name, there are several theories. For one could with " night shade " the dark berries of black nightshade be meant, on the other hand is also the medicinal properties of plants, a possible derivation. Otto Brunfels writes in 1532 in his Contrafayt Kreüterbuch: " Diss herb Württemberg otherwise used, against the damage which the witch people cause, and the uff mancherley white, nor occasion of widerfarenden made damage, not on sonderliche superstición and magia. Wherefore Württemberg in sonderheyt Nachtschatt called. " Johann Christoph Adelung (1808 ) sees the origin of the name in connection with the headache ( damage) that cause the strong night -scented flowers of the plants.
The name Solanum was taken over by Linnaeus by other authors, the former importance included, among other deadly nightshade ( Atropa ), peppers ( capsicum), datura ( Datura ), jujubes (Physalis ) and nightshade (Solanum ). However, quite different groups of plants were subordinated to that name part, such as magic flowers ( Mirabilis ), oneberries (Paris) and pokeweed (Phytolacca ). The origin of the scientific name is the same as that of the German name not released. The connection to the Latin sol ( sun), which is called by some authors is not to accept loud Genaust more likely to derive from the Latin Solari is ( comfort, ease ), which could indicate the medicinal effects of low doses of the nightshade family.