Collerette type dahlias take on the form of a single dahlia but with a difference. They still retain the simple outer row of almost flat petals that can often overlap, and the centre of the flower is clearly visible as a disc. However, the disc is encircled by a ‘collar’ of small florets or petaloids that create an almost fluffy or ruffled look to the flower as a whole.
Dahlia is a genus of bushy, tuberous, herbaceous perennial plants native to Mexico. A member of the Asteraceae [or Compositae], dicotyledonous plants, related species include the sunflower, daisy, chrysanthemum and zinnia. There are 42 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 2 in [5.1 cm] diameter or up to 1 ft [30 cm] or “dinner plate”.