Dahlia
The dahlia (Dahlia ), rarely even dahlias, form a genus of flowering plants in the sunflower family ( Asteraceae).
Features
Dahlias are perennial herbaceous plants, sometimes woody at the base of the stem slightly, rarely climbing epiphytes (Dahlia macdougallii ). They form tubers or tuberous rhizomes thickened as outlasting. Dahlia macdougallii forms aerial roots. The upright, usually unbranched stems are individually, in pairs until the fourth or numerous in bundles depending on the section. The real arranged opposite or in whorls threefold leaves are easily assembled to ternate fiedrig; the leaf edge can be finely ciliate. Stipules are often present.
The round bloom conditions are to long, slender and leafless inflorescence stems. The bracts are in two rows. The five (rarely four to seven) outer bracts are narrow-linear to ovate - roundish, narrowed at the base and at flowering time upright, spreading or repulsed, fleshy and green, the eight (rarely seven or nine ) inner are membranous, whitish at the edges - translucent or dry, otherwise brown to red, often sold purple or red at the tips, ovoid and at the tips of nearly acute to obtuse, crop time enlarging.
The achenes are beaked.
The chromosome numbers usually be 2n = 16, in some cases also 17 and 18, occasionally occurs tetraploidy.
Dissemination
The genus is native to the highlands of Mexico and Guatemala.
System
The genus is divided into four sections and contains about 35 species, including:
- Section Pseudodendron Dahlia imperialis
- Dahlia excelsa
- Dahlia tenuicaulis
- Section Epiphytum Dahlia macdougallii
- Section Entemophyllon Dahlia scapigeroides
- Dahlia foeniculifolia
- Dahlia linearis
- Dahlia rupicola
- Section Dahlia Merck dahlia ( Dahlia merckii )
- Dahlia cardiophylla
- Dahlia apiculata
- Dahlia purpusii
- Großfiedrige dahlia ( Dahlia pinnata )
- Dahlia Pteropoda
- Dahlia rudis
- Dahlia brevis
- Dahlia moorei
- Dahlia hintonii
- Dahlia mollis
- Dahlia atropurpurea
- Scarlet Dahlia (Dahlia coccinea)
- Dahlia australis
- Dahlia sherffii
- Dahlia scapigera
- Dahlia barkerae
- Dahlia tenuis
A hybrid is the
- Garden Dahlia (Dahlia hortensis × )
Botanical history
The first written records of dahlias we owe to the Spanish physician Francisco Hernandez from the end of the 16th century.
1791 then sent Vicente Cervantes from the Botanical Garden Mexico City dahlia seeds to Madrid to José Antonio Cavanilles, then employees and later director of the Real Jardin Botanico de Madrid. That same year, the plant flourished, and on the basis of Dahlia pinnata Cavanilles made the first scientific description of the genus to. Your name honors the Swedish botanist Andreas Dahl. Later Cavanilles described two other species, namely Dahlia rosea and Dahlia coccinea.
A later synonym for the genus is Georgina Georgina or after coming from Pomerania St. Petersburg botanist Johann Gottlieb Georgi. 1805 awarded in error by Carl Ludwig Willdenow, 1810 but corrected, the term stood among breeders and is in Scandinavia and Eastern Europe still in use today as a common name for the dahlias.
By further new taxa in particular the end of the 19th and the first half of the 20th century ( Hemsley, Sherff, Paul D. Sørensen ), the number of species included enlarged until 1969 to 24 by later authors, the number of species increased to now approximately 35
Use
Dahlias are popular as ornamental plants with large, decorative inflorescences in many colors and color combinations in countless hybrid breeding forms.
All crops go back to the intersection of only two types, namely, Dahlia coccinea and Dahlia pinnata. The number of varieties in the thousands, in breeding circles is a classification of ten groups in use, in which the varieties are classified according to size and type of inflorescence.
In Europe, they bloom from summer to autumn, but are not hardy, so that the tubers must be overwintered indoors.
Due to their popularity, there are numerous dahlias every year festivals, exhibitions, and breed shows, such as the dahlia garden in Gera.
Trivia
The Zwergdahlie Dahlia × hybrida ' Red Schorsch " was chosen as the Bavarian balcony plant of 2009.