Dahlia Information
Like a great many other flowers in the garden the dahlia is a member of the natural order of the Compositae, a family which ranges from the lowly daisy of the fields to the majestic flower about which this book is written. More accurately it is included in a sub-order of the Compositae, the Helianthoid eae, along with the sunflower and the aster.
The soil in which it grows is sandy and yet rich so that although the great demand for water is met by the heavy rainfall the fleshy tubers are not endangered by boggy conditions as excess moisture quickly drains away.
The commonest mistake made is to regard it as a sub-tropical plant. This is not true of the types from which our garden hybrids have developed, as these are found only on the high plains of Mexico, at altitudes of 3,000 ft or over, where the climate is temperate, except that frost is seldom experienced. There is every reason to believe that if it were not for our wet winters the dahlia could have been naturalised in this country, at least in the milder areas.
Nevertheless it is unlikely that the doubling of the flower will ever be so complete that the flower is itself sterile; usually some disc florets will appear, albeit rather late in the life of the individual blooms, and it is thus possible to obtain some seed.
The greatest obstacle to obtaining seed from the intensely double giant decorative varieties is the length of time taken for the bloom to develop to the fertile stage, and the absence of long periods of sun. In this country, which has comparatively short, cool and damp seasons, it is not uncommon to find it impossible to obtain seeds from such varieties.
Some revulsion against the intense formality of the globular dahlias later became apparent, and for some years interest declined until the introduction of a new factor brought renewed life. This was the advent about 1890 of seedlings from D. Juarqii, an almost sterile hybrid with loosely arranged, somewhat pointed florets: representative of a type that had been bred practically out of existence.
