Wednesday, August 10, 2011

Botanical description of Gerbera flower




The gerbera is defined as a monoicous  plant, as it possesses both massculine organs (stamens) and female organs (pistils) on the same inflorescenence. The inflorescence, typical of the compositeae, are made of small flowers (florets or flowerets) inserted in a singlle spongy cup shaped receptacle (centre or central disc). The small flowers towards the centre are called tubulose flowers, whilst those near the outside are called ligulate flowers. The latter posses a small corolla at the base, a part of which lengthens to form a long, coloured, tongue-like shape, that also determines the coloration typical of the gerbera (red, white, yellow,etc).

The ligulate flowers (also called ray florets or ligulate ray florets) are functionally female, since even if thin file- like stamens (masculine flowers) are present, the anthers (pollen grain) are not formed. The number of ligulate flowers varies from type to type, but generally there are more than 50.

The tubular flowers is a central disc (also called disc florets) have a very small tubular corolla that frequently appears yellow before the anthesis (flowering). Subsequently the corolla opens two form two or more small edges (similar to tiny tongue- like shapes), whose external surfaces are generally of the same colour as the ligulate flowers.

Those flowers (tubular) are functionally male, since even if they posses a stamen with pollen, the external surface of the pistils (stigma) remains seemingly unreceptive (meaning that the pollen cannot enter onto the stigma)

Finally, intermediary forms of inflorescence also exist, generally located between the disc  and the ligulate flowers. These include, hermaphroditic flowers that produce pollen and posses receptive stigmas,and flowers have a base pappus composed of 200 hairs, while the tubuluse flowers have a pappus of around 60 hairs.
The central disc, heart or centreof the inflorescence has a different colour from the ligules. In fact, once it reaches maturity, it can be of a green or brown colour with different shades. The flowering of the head (inflorescence) is essentially proterogynic. Generally the peripheral female ligulate flowers mature first, and then the internal male ones, rendering self fertilization difficult, but favouring crossbreads between the varieties.

From the subsequent studies it also appears that:
Ø  The percentage of autogamy (self- fertility) is about 35%.
Ø  The production of seeds varies notably from variety to variety.
Ø  The plants least fertile with self pollination are also those least fertile with cross- pollination.
Ø  The highest production os seeds is in the period of May- June.
Ø  The inflorescence with a large central disc produce more seeds than those with a small central disc.

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