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Posted on 4:59 AM by Wanto and filed under
By James Marissa
The habits and formation of the dahlia are peculiarly suited to its natural environment. A native of Mexico, it experiences a high rainfall during the growing season, followed by an almost complete drought during the resting period.
A tuberous rooted, half-hardy perennial, like all its fellow members of the Compositae its blooms are actually composed of a number of flowers, consisting of a certain number of ray florets, in which the male organs have been changed into a strap shaped petal, surrounding a central disc of bisexual florets. The ray florets may be of a wide range of colours, but the disc florets are usually yellow.
The individual florets are separated by scales (bracteoles) which serve as calyces for the protection of the seed case (the ovary). These remain on the flower head after the florets have been removed or have dried out, closing round the developing seed to form a protective sheath.
Even as it is, dahlias will occasionally survive the winter if left in the ground, but this can hardly be recommended as a general practice. The tubers are designed to resist drought, but not the damp coldness of our soils during winter.
Doubling in the dahlia is not of recent origin as it is evident that at least one species, D. Variabilis, produced some semi-double blooms naturally. It is not surprising therefore that shortly after its introduction into Europe fully double dahlias were raised. The earliest had more or less flat florets and from these evolved the ball-shaped formal blooms which were to exclude practically all other forms for many years. A later variant had short tubular florets incurving at the margin: the forerunner of the Double Show and Fancy and the pompons still widely grown today.
At first the plant relies upon nourishment obtained from the tuber but at a later stage fresh roots develop from the base of each green shoot to supply the growing demands of the plant. These fresh roots themselves develop into tubers by the end of the growing season and the old root system then gradually dries out and will eventually rot away.
A tuberous rooted, half-hardy perennial, like all its fellow members of the Compositae its blooms are actually composed of a number of flowers, consisting of a certain number of ray florets, in which the male organs have been changed into a strap shaped petal, surrounding a central disc of bisexual florets. The ray florets may be of a wide range of colours, but the disc florets are usually yellow.
The individual florets are separated by scales (bracteoles) which serve as calyces for the protection of the seed case (the ovary). These remain on the flower head after the florets have been removed or have dried out, closing round the developing seed to form a protective sheath.
Even as it is, dahlias will occasionally survive the winter if left in the ground, but this can hardly be recommended as a general practice. The tubers are designed to resist drought, but not the damp coldness of our soils during winter.
Doubling in the dahlia is not of recent origin as it is evident that at least one species, D. Variabilis, produced some semi-double blooms naturally. It is not surprising therefore that shortly after its introduction into Europe fully double dahlias were raised. The earliest had more or less flat florets and from these evolved the ball-shaped formal blooms which were to exclude practically all other forms for many years. A later variant had short tubular florets incurving at the margin: the forerunner of the Double Show and Fancy and the pompons still widely grown today.
At first the plant relies upon nourishment obtained from the tuber but at a later stage fresh roots develop from the base of each green shoot to supply the growing demands of the plant. These fresh roots themselves develop into tubers by the end of the growing season and the old root system then gradually dries out and will eventually rot away.
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