Dahlias

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Dahlias
Scarlet Dahlia (Dahlia coccinea)

Scarlet Dahlia ( Dahlia coccinea )

Systematics
Euasterids II
Order : Astern-like (Asterales)
Family : Daisy family (Asteraceae)
Subfamily : Asteroideae
Tribe : Coreopsideae
Genre : Dahlias
Scientific name
Dahlia
Cav.

The Dahlias ( Dahlia ), rarely even dahlias called, form a plant genus in the family of the daisy family (Asteraceae). Many varieties are used as ornamental plants .

description

Vegetative characteristics

Dahlias are perennial herbaceous plants that sometimes become somewhat lignified at the base of the stem, rarely climbing epiphytes ( Dahlia macdougallii ). They form tubers or bulbous, thickened rhizomes as persistence organs. Like Dahlia imperialis, they can reach heights of up to 8-10 meters. Dahlia macdougallii forms aerial roots . The upright, mostly unbranched stems are, depending on the section, individually, in pairs to four or numerous in bundles.

The real opposite or in threefold Wirteln arranged leaves are easily assembled to ternate fiedrig; the leaf margin may be ciliate. Stipules are often present.

Generative characteristics

The round, cup-shaped inflorescences are on long, slender and bare inflorescence stalks. The bracts are in two rows. The five (rarely four to seven) outer bracts are narrow linear, narrowed to ovate-rounded at the base and anthesis upright, spreading or repulsed, fleshy and green, the eight (rarely seven or nine) inside are membranous, whitish at the edges - translucent or dry, otherwise brown to red, often purple or red at the tips, egg-shaped and nearly pointed to blunt at the tips, enlarging at the time of fruiting.

The achenes are not beaked.

The chromosome numbers are usually 2n = 16, occasionally also 17 and 18, occasionally tetraploidy occurs.

distribution

The genus Dahlia is native to the plateaus of Mexico and Guatemala as far as Colombia.

Systematics

Section pseudodendron : Dahlia imperialis
Section pseudodendron : Dahlia tenuicaulis
Dahlia Section : Merck Dahlia ( Dahlia merckii )
Section Dahlia : Dahlia sherffii

The genus is divided into four sections and contains around 35 species:

  • Section Pseudodendron Sherff : The species in this section are lignified, have a trunk diameter between 1.5 centimeters and 10 centimeters and reach heights of 2–9 meters.
  • Section Epiphytum Sherff : With only one species:
    • Dahlia macdougallii Sherff : It is a liana with trunks that are up to 5 centimeters thick and up to 20 meters long. They can grow up to 10 meters tall. The species is only known from one location in the Mexican state of Oaxaca .
  • Section Dahlia : The species in this section reach heights of 30 centimeters to 3 meters.
    • Merck dahlia ( Dahlia merckii loam. ): It occurs in Mexico in the states of Guerrero , Hidalgo , Morelos , Nuevo León, Puebla , San Luis Potosí , Tamaulipas and Veracruz . It has the number of chromosomes 2n = 32.
    • Dahlia cordifolia (Sessé & Moc.) McVaugh (Syn .: Dahlia cardiophylla S.F. Blake & Sherff ): It occurs in the Mexican state of Guerrero . It has the number of chromosomes 2n = 32.
    • Dahlia apiculata (Sherff) PDSørensen : It occurs in the Mexican states of Oaxaca and Puebla . It has the number of chromosomes 2n = 32.
    • Dahlia purpusii Brandegee : It is only known from one location in the Mexican state of Chiapas .
    • Garden Dahlia ( Dahlia × pinnata Cav .; Syn .: Dahlia rosea Cav. , Dahlia variabilis (Willd.) Desf. , Dahlia × hortensis Guillaumin , Georgina variabilis Willd .; = Dahlia coccinea × Dahlia sorensenii ): It is only in culture known.
    • Dahlia sorensenii H.V. Hansen & Hjert. : It occurs in the Mexican states of Hidalgo, San Luis Potosí, México and in the federal district of Mexico City. It has the chromosome number 2n = 64.
    • Dahlia pteropoda Sherff : It occurs only in the Mexican state of Puebla. The number of chromosomes is 2n = 64.
    • Dahlia rudis P.D. Sørensen : It occurs in the Mexican state of Hidalgo and in the federal district of Mexico City. It has the number of chromosomes 2n = 32.
    • Dahlia brevis P.D. Sørensen : It occurs in the Mexican state of México. It has chromosome number 32.
    • Dahlia moorei Sherff : She is only known from one place in the Mexican state of Hidalgo .
    • Dahlia hintonii Sherff : It only occurs in the Mexican state of Guerrero.
    • Dahlia mollis P.D. Sørensen : It occurs in the Mexican state of Hidalgo . It has the number of chromosomes 2n = 32.
    • Dahlia barkerae Knowles & Westc. : It only occurs in the Mexican state of Michoacán . It has the chromosome number 2n = 64.
    • Dahlia atropurpurea P.D. Sørensen : It occurs in the Mexican states of Guerrero and México. It has the chromosome number 2n = 64.
    • Scarlet Dahlia ( Dahlia coccinea Cav. , Syn .: Dahlia popenovii Saff. ): The home is Mexico, Belize and Guatemala. It has the number of chromosomes 2n = 32 or 64.
    • Dahlia australis (Sherff) PD Sørensen : It occurs in the Mexican states of Chiapas , Oaxaca , maybe also Hidalgo and also in Guatemala in the departments of Huehuetenango and Totonicapán . It has the number of chromosomes 2n = 32 or 64.
    • Dahlia sherffii P.D. Sørensen : It occurs in the Mexican states of Chihuahua and Durango . It has chromosome number 32 or 64.
    • Dahlia scapigera (A. Dietr.) Knowles & Westc. : This species is dwarfed and only 20–40 centimeters tall. Their home is in the Mexican states of México, Michoacán and the federal district of Mexico City.
    • Dahlia tenuis B.L. Rob. & Greenm. : It only occurs in the Mexican state of Oaxaca . It has the number of chromosomes 2n = 32.
    • Dahlia tubulata P.D. Sørensen : It only occurs in the Mexican states of Nuevo León and Tamaulipas . It has the number of chromosomes 2n = 32.
    • Dahlia parvibracteata Saar & PDSørensen : This species, first described in 2000, only occurs in the Mexican state of Guerrero . It has the number of chromosomes 2n = 32.
    • Dahlia neglecta Saar : This species, first described in 2002, only occurs in the Mexican state of Hidalgo . It has the chromosome number 2n = 64.
    • Dahlia hjertingii H.V. Hansen & PDSørensen : This species, which was first described in 2003, only occurs in the Mexican state of Hidalgo . It has the number of chromosomes 2n = 32.
    • Dahlia cuspidata Saar, PDSørensen & Hjert. : This species, first described in 2003, is only known from one location in the Mexican state of Hidalgo .
    • Dahlia spectabilis Saar & PDSørensen : This species, which was first described in 2002, is only known from one place in the Mexican state of San Luis Potosí . It has the chromosome number 2n = 64.

Botanical history

We owe the first written records of dahlias to the Spanish doctor Francisco Hernandez from the end of the 16th century .

Then in 1791 Vicente Cervantes sent dahlia seeds from the Mexico City Botanical Garden to Madrid to Antonio José Cavanilles , then an employee and later director of the Real Jardín Botánico de Madrid . In the same year the plant bloomed, and Cavanilles made the first scientific description of the genus based on Dahlia pinnata . Her name honors the Swedish doctor and botanist Anders Dahl (1751–1789). Cavanilles later described two more species, namely Dahlia rosea , which is seen as a synonym for Dahlia pinnata , and Dahlia coccinea .

A later synonym for the genus is Georgine or Georgina after the St. Petersburg botanist Johann Gottlieb Georgi , who came from Pomerania . Erroneously assigned by Carl Ludwig Willdenow in 1805, but corrected in 1810, the name remained among breeders and is still in use today as a trivial name for dahlias in Scandinavia and Eastern Europe .

Further new descriptions, especially at the end of the 19th and first half of the 20th century ( Hemsley , Sherff , Paul D. Sørensen), increased the number of species recorded to 24 by 1969. Later authors increased the number of species to meanwhile around 35.

use

Dahlia hybrid

Dahlias are popular as ornamental plants in countless hybrid cultivars with large, decorative inflorescences in many colors and color combinations.

All cultivated plants go back to the crossing of only two species, namely Dahlia coccinea and Dahlia pinnata . The number of varieties is in the thousands, in breeding circles a system of ten groups is common, in which the varieties are divided according to size and type of inflorescences.

In Europe , they bloom from summer to autumn , but are not hardy , so the tubers have to be overwintered indoors.

The tuber of the dahlia is edible, but after the European conquest of South America it was more and more forgotten as a food crop.

Due to its popularity, there are numerous dahlia festivals, exhibitions and breeding shows every year, for example the dahlia garden in Gera or the annual dahlia show in Lindau / Bodensee (September and October).

Trivia

The flower of the dahlias in the German national colors is the symbol of the campaign Germany - Land of Ideas , which was launched in 2005. The dahlia was first brought to Germany by the researcher Alexander von Humboldt . It is intended to show Germany's willingness to innovate and research.

The dwarf dahlia Dahlia × hybrida 'Roter Schorsch' was chosen as the Bavarian balcony plant of the year 2009.

literature

Web links

Commons : Dahlias ( Dahlia )  - Collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj Hans V. Hansen: Simplified keys to four sections with 34 species in the genus Dahlia (Asteraceae - Coreopsidae) . In: Nordic Journal of Botany, vol. 24, p. 549-553, 2004
  2. ^ A b c d e Dahlia in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved May 2, 2016.
  3. ↑ Lotte Burkhardt: Directory of eponymous plant names . Extended Edition. Botanic Garden and Botanical Museum Berlin, Free University Berlin Berlin 2018. [1]
  4. ↑ Gordon Cheers (Ed.): Botanica. The ABC of plants. 10,000 species in text and images . Könemann, Königswinter 2003, ISBN 3-8331-1600-5 , p. 287.
  5. ↑ Ulrike Reeg, Pasquale Gallo "Interface interculturality: Contributions to didactics" p. 74
  6. ↑ Baptism of the Bavarian balcony plant of the year 2009 in Middle Franconia . Roter Schorsch is intended to carry garden lovers off into the summer. ( Online (PDF; 463 kB)).