Potato ( Solanum tuberosum )

Systematics
 Nuclear eudicotyledons Asterids Euasterids I Order : Nightshade (Solanales) Family : Nightshade family (Solanaceae) Genre : Nightshade
Scientific name
Solanum
L.

Nightshade ( Solanum ) is a genus in the nightshade family (Solanaceae). The genus contains about 1400 species . As a rule, they are herbaceous plants that grow upright to creeping, sometimes also creeping. In the tropics there are also lignifying species: shrubs and even trees up to 20 m high.

Well-known useful plants of the genus are the potato ( Solanum tuberosum ), the aubergine ( Solanum melongena ) and the tomato ( Solanum lycopersicum ), but there are many other species that are important as food, medicinal plants ( Solanum nigrum and Solanum dulcamara ) or ornamental plants have for humans. Many nightshades are poisonous to humans or have poisonous parts. The cause are mostly various alkaloids .

Due to the size of the genus, among other things, the system is still very uncertain. For example, tomatoes and tamarillos have long been classified in the independent genera Lycopersicon and Cyphomandra , currently these groups are subordinated to the genus nightshade.

## description

### Vegetative characteristics

Nightshade species are short-lived or perennial herbaceous plants or woody plants that grow as shrubs, lianas or trees and can reach heights of up to 20 m or are prostrate or climbing. The stem axis shows a sympodial branching scheme, that is, the stem axis divides further and further into secondary branches during growth. There stolon- , rhizome , tuberous or brut bodying agents. Some of the shoots have spines or are hairy with trichomes . The latter can be very diverse, there are simple, glandular, star-shaped, tree-like or sea urchin-like branched forms. The spines can usually be found on the sprouts, the leaves or the calyx, they can be straight or bent back, thin and needle-like or have a broadened base. The leaves are simple or compound, preserved or, more rarely, perched. The leaf margin is entire, serrated, lobed or curved. The leaves of all nightshade species are alternate, but the leaf positions often appear opposite or in pairs, which can be caused by complex growth patterns.

### Flowers and inflorescences

The inflorescences develop terminally, in the branch axils, opposite the leaves or outside of branches. They form dichotomous or uniaxially branching, occasionally also wrap-like umbels from two to ten, more rarely up to 20, but also up to 300 flowers . They are often arranged in clusters or in umbels , but in many species the inflorescences are reduced to simple, clustered, single-bifurcated structures.

The flowers are mostly small, are rarely solitary, are almost sessile or short-stalked, occasionally zygomorphic (monosymmetric). Single-sex flowers occur very rarely, usually there are completely bisexual flowers at the base of the inflorescence, while the outer flowers only have male reproductive organs, dioeciousness occurs only in exceptional cases. The inflorescence is usually five-fold, but occasionally also four, six or ten-fold. The bell-shaped calyx consists of five calyx lobes or segments, some of which enlarge after the flowering phase. The corolla is colored white, green, yellow, pink or purple, it lacks the inner ring of trichomes, it is wheel-shaped, broadly bell-shaped-wheel-shaped or star-shaped. Purely bell-shaped crowns as in Solanum fiebrigii are known only from very few species. The corolla tube is very short, the hem is five-angled, heavily divided or slightly lobed, with the lobes or segments protruding or bent back. The flowers are fertilized mainly by pollen-collecting bees .

The five stamens are usually the same length, but sometimes stamens of different lengths appear within a flower, then one stamen is longer than the other four. The stamens are generally much shorter than the anthers , only rarely are they the same length or even longer. The stamens are usually divided into two sectors: The basal part is fused with the corresponding parts of the neighboring stamens and completely with the corolla tube, the part further away from the base is usually a little shorter than the first part, is occasionally free, but can also grow together with the neighboring parts, so that a 0.2 to 1.5 mm wide ring is created. The anthers are partially pointed towards the tip, sometimes a little wider at the tip than at the base. They may or may not be affectionate to one another; in exceptional cases they are partially or completely grown together. Usually starting from the top they jump up with holes or holes along the longitudinal axis; sometimes a crack follows along the longitudinal axis, which can be short but can also reach the base of the dust bag. The species of the section Lycopersicum (the earlier genus of tomatoes) deviate from this scheme , in which the anthers pop open with elongated cracks. The pollen grains are usually three-fold, in some species a part is also four-fold, the outer layer of the pollen grain wall is granular. In those cases in which dioeciousness occurs, the pollen that is formed in the female flowers is apertureless . The size of the pollen grains is mostly small (10 to 25 µm), more rarely medium (25 to 28 (30) µm) and in exceptional cases larger (41 to 45 µm).

The female flower parts consist of two carpels , the ovary is two-chambered, the nectaries are missing. The stylus is hairless or covered with trichomes, straight or curved, cylindrical or enlarged in the basal two-thirds, rarely inverted awl-shaped. In some of the species the styles are dimorphic, there then exist flowers with short and long styles at the same time. The scar is spherical and not flattened, saddle-shaped or disc-shaped and not flattened.

### fruit

Black nightshade fruits ( Solanum nigrum )

The fruits are berries with a juicy, slimy or fleshy pericarp with or without stone cells , sometimes there are deviations, then the fruits can be woody or dry, popping up and becoming a capsule fruit . The shape of the berries is usually more or less spherical, (5) 9 to 20 (35) mm in diameter, but sometimes even larger. The calyx remains on the fruit, partially bends back and / or enlarges. Usually there are around 20 to 80 seeds in a fruit , but there are also species with up to 1,600 to 1,800 seeds per fruit. The seeds are disc-shaped or kidney-shaped, heavily indented, 1.2 to 4 (rarely up to 7 or 8) mm long, usually somewhat pitted. The embryo is strongly helical, the cotyledons are shorter than the rest of the embryo, the endosperm is abundant.

## Distribution and habitats

The nightshades have worldwide distribution with the exception of the areas near the North Pole . Centers of diversity and endemism are mainly in the Andes, as well as in North America and Mexico , Central America , eastern Brazil , the Caribbean , Australia , Africa and Madagascar .

Within these distribution areas, the nightshades have adapted to a large number of different habitats . They occur at altitudes from 0 to 4500 m and also populate areas with extreme environmental conditions such as deserts and rainforests .

## Chromosome number

Due to the size of the genus and the sometimes unclear systematics, there is still no complete investigation of the number of chromosomes within the genus. Most of the species studied, however, have a base number of chromosomes , are diploid, and thus have 24 chromosomes. Polyploidy is very common, so there are representatives with chromosome sets of , and . Exceptions are seven known species of the Australian section Archaesolanum with , Solanum bullatum with and the cow udder plant with . ${\ displaystyle x = 12}$${\ displaystyle 2n = 4x = 48}$${\ displaystyle 2n = 6x = 72}$${\ displaystyle 2n = 8x = 96}$${\ displaystyle x = 23}$${\ displaystyle n = 15}$${\ displaystyle n = 11}$

Solanum bonariense

## Systematics

### Internal system

The most widespread systematics based on morphological features is the systematics established by William D'Arcy in 1972 and expanded in 1991. It divides the genus into the following seven sub-genera. These sub-genres were initially divided into 52, and in the extended system into 64 sections. Armando Hunziker's 2001 work "The Genera of Solanaceae" refers to D'Arcy's 1972 system, but due to more recent morphological work does not take over all sections and rearranges others within the genre. 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 setting a separate classification. The following list shows the classification of the genus according to the status of Hunziker.

1. Solanum subg. Archaesolanum Marzell
2. Solanum subg. Bassovia (Aubl.) Bitter
3. Solanum subg. Leptostemonum (Dunal) bitter
4. Solanum subg. Lyciosolanum bitter
5. Solanum subg. Minon Raf. (after D'Arcy 1972 and Hunziker 2001 subg.Brevantherum (Seithe) D'Arcy )
Sections Brevantherum Seithe , Holophyllum (G.Don) Walp.
6. Solanum subg. Potatoe (G. Don) D'Arcy
Sections Petota , Neolycopersicon , Dulcamara , Glaucophyllum A. Child , Basarthrum , Jasminosolanum Seithe , Rhychantherum
7. Solanum subg. Solanum
Sections Quadrangulare , Benderianum , Afrosolanum , Lemurisolanum , Macronesiotes , Solanum , Episarcophyllum Bitter , Delitescens Barboza & Hunz. , Capanulisolanum bitter , Geminata , Pseudocapsica Roem. & Schult. , Chamaesarachidium

According to Hunziker, the Herpystichum , Herposolanum , Cyphomandropsis and Regmandra sections remain without being classified in any of the sub-genera . The Normania described by D'Arcy as a section are given the status of an independent genus again according to Hunziker.

A phylogenetic study using ndhF ( nicotinamide adenine dinucleotide - dehydrogenase type F) data on 115 nightshade species by Lynn Bohs revealed that some of the subgenera used by D'Arcy are not monophyletic . According to their results, the genus Solanum can be divided into twelve large clades . In contrast to D'Arcy's system, the tomatoes ( Lycopersicon ), Tamarillos ( Cyphomandra ), Normania and Triguera are regarded as sections within the genus Solanum .

However, a final systematics cannot yet be established based on these investigations, because on the one hand the relationships among the clades cannot be clearly determined by the results and, on the other hand, the results would have to be confirmed by corresponding investigations of other genes, as well as morphological and biochemical properties.

## Botanical history

Early illustration of the potato ( Solanum tuberosum ) by Charles de l'Écluse (1583)

The genus was first described in 1753 by Carl von Linné in his work Species Plantarum , he listed a total of 23 species under the generic name Solanum , mainly European and American species. Among other things, he referred to the work of Dillenius from 1732. In the period that followed, the number of species assigned to this genus increased steadily. In Michel Félix Dunal's work Histoire naturelle, médicale et économique des Solanum et des genres qui ont été confundus avec eux , published in 1813 , a total of 235 species were distinguished, in the revised version from 1816 already 321. For the Prodromus systematis published by Alphonse Pyrame de Candolle naturalis regni vegetabilis , Dunal wrote a comprehensive monograph of the genus until 1852 with a range of around 900 species. The genera Lycopersicon and Cyphomandra , which are now counted as sections Lycopersicum and Pachyphylla to the genus Solanum , he led as separate genera in this work.

Dunal initially divided the nightshade into two groups, Inermia for species with spines and Aculeata for species without spines. To 1852 he developed therefrom to divide the genus in the sections, which also other morphological features such as the form of a first lug, dust bag noticed. Georg Bitter presented a further subdivision in 1919, but referred to the same characteristics as Dunal.

The distinction between the genus presented in 1962 by Almuth Seithe did not refer to anthers and spines, but solely to the morphology of the trichomes. This system was expanded in 1970 by S. Danert to include 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 established in 1972 by William D'Arcy and which divides the genus into seven sub-genres, which for a long time was the most commonly used system. D'Arcy expanded his system in 1991 to include more sections and renamed one section. Further approaches to subdivide the genus were presented by Michael Nee in 1999 (but only for species of the New World) and in 2001 by A. Child and RN Lester. Armando Hunziker , in his book The Genera of Solanaceae , published in 2001, refers to the classification by D'Arcy with the status of 1972, but makes minor changes to include more recent scientific findings in the classification. Most of the works list features or the characteristic species of the subgenera, sections and series, a complete list of the species contained is only drawn up by Nee. This makes it difficult to compare the different types of work.

Despite intensive research into the genus, no complete treatment of the genus down to the species level has been published since Dunal's publication in 1852. Research groups headed by Lynn Bohs ( University of Utah ), Sandra Knapp ( Natural History Museum , London), Michael Nee ( New York Botanical Garden ) and David Spooner ( University of Wisconsin ) have been working on a new, complete monograph of the genus since 2004 . The joint project is funded by the US National Science Foundation . An important result of this work is the subdivision according to cladistic points of view established by Lynn Bohs in 2005 and by Terri Weese and Lynn Bohs in 2007 , which describes a total of 13 major clades within the genre.

## Origin of name

The name Nachtschatten (formerly also Nachtschatt ) is derived from the Old High German nahtscato or Middle High German seamschate . There are several theories for the interpretation of the name. On the one hand, the dark berries of the black nightshade could be meant by "nocturnal shade" , on the other hand the medicinal effect of the plants (especially of the black nightshade, but also of the "red" nightshade, Solanum dulcamara , and other nightshade plants) is possible Derivation. Otto Brunfels wrote in 1532 in his Contrafayt Kreüterbuch : “This herb would also be used in other ways, against the damage that the witches inflict on the people, and the sometimes white, still opportunity of the damage encountered, not on special supersticion and magic. That is why it is called Nightshade in sonderheyt . ” Johann Christoph Adelung (1808) sees the origin of the name in connection with the headache (damage) caused by the flowers of the plants, which are strongly scented at night.

The name Solanum was taken over by Linnaeus from other authors, the meaning at that time included deadly nightshade ( Atropa ), paprika ( Capsicum ), thorn apple ( Datura ), bladder cherries ( Physalis ) and the nightshade ( Solanum ). But also very different groups of plants that name were subordinated to some extent, for example, magic flowers ( Mirabilis ), oneberries ( Paris ) and pokeweed ( Phytolacca ). The origin of the scientific name as well as that of the German name has not been clarified. The connection to the Latin sōl (sun), which is mentioned by some authors, is not to be assumed according to Exactly , the derivation from the Latin solari (to comfort, to alleviate) is more likely , which could indicate the medicinal effects of small doses of nightshade family.

## swell

1. a b c d Sandra Knapp: A revision of the Dulcamaroid Clade of Solanum L. (Solanaceae). In: PhytoKeys , Volume 22, May 10, 2013. pp. 1-428. doi : 10.3897 / phytokeys.22.4041
2. Armando T. Hunziker: The Genera of Solanaceae . ARG Gantner Verlag KG, Ruggell, Liechtenstein 2001, ISBN 3-904144-77-4 .
3. a b Solanum Morphology . From: PBI Solanum: A worldwide treatment , accessed on August 5, 2007
4. ^ Solanum Distribution . From: PBI Solanum: A worldwide treatment , accessed on August 5, 2007
5. a b Lynn Bohs: Major Clades in Solanum based on ndhF Sequence Data. In: Solanaceae: William G. D'Arcy Memorial , V. Hollowell et al. (Editors). Monographs in Systematic Botany from the Missouri Botanical Garden. 2005. Pages 27-49.
6. Caroli Linneani: Species Plantarum . Volume 1, 1753. pp. 184-188
7. a b c d Terri L. Weese and Lyn Bohs: A Three-Gene Phylogeny of the Genus Solanum (Solanaceae). In: Systematic Botany , Volume 32, Number 2, 2007. pp. 445-463. doi : 10.1600 / 036364407781179671
8. Project description PBI Solanum: A worldwide treatment. Retrieved August 4, 2007
9. Quoted from Marzell, Volume 4, page 366
10. ^ Heinrich Marzell, Heinz Paul: Dictionary of German Plant Names . Licensed edition Parkland Verlag, Cologne 2000. Photomechanical reprint of the first edition 1979, ISBN 3-88059-982-3 .
11. Helmut Genaust: Etymological dictionary of botanical plant names. 3rd, completely revised and expanded edition. Birkhäuser, Basel / Boston / Berlin 1996, ISBN 3-7643-2390-6 .