Thursday 11 April 2019

DAHLIA

Dahlia is a genus of bushy, tuberous, herbaceous perennial plants native mainly in Mexico, but also Central America, and Colombia. A member of the Asteraceae or Compositae, dicotyledonous plants, related species include the sunflower, daisy, chrysanthemum and zinnia. There are at least 36 species of dahlia, with hybrids commonly grown as garden plants.

Flower forms are variable, with one head per stem; these can be as small as 5.1 cm diameter or up to 30 cm ("dinner plate"). This great variety results from dahlias being octoploids (that is, they have eight sets of homologous chromosomes), whereas most plants have only two. In addition, dahlias also contain many transposons (genetic pieces that move from place to place upon an allele), which contributes to their manifesting such great diversity.

The stems are leafy, ranging in height from as low as 30 cm to more than 1.8–2.4 m. The majority of species do not produce scented flowers or cultivars. Like most plants that do not attract pollinating insects through scent, they are brightly coloured, displaying most hues, with the exception of blue. Dahlias bloom all Summer and most of Autumn in temperate climates, making quite a show in our Autumn garden at the moment.

The dahlia was declared the national flower of Mexico in 1963. The tubers were grown as a food crop by the Aztecs, but this use largely died out after the Spanish Conquest. Attempts to introduce the tubers as a food crop in Europe were unsuccessful.

The variety shown here, 'York & Lancaster' is an unusual and very beautiful dahlia whose origins in history have been lost centuries ago. As well as being of striking appearance, it is a cultivar that most dahlia experts have never heard of, while for others it's a genetic conundrum that shouldn't really exist. For a dahlia it is surprisingly tough, almost hardy in light soils. Standing approximately 80 cm tall it produces large numbers of ball shaped flower heads. If it does throw up an occasional pure white flower it will always be followed by a brilliant white and carmine red bi-colour flower.

This post is part of the Floral Friday Fotos meme.

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