Leaf colour patterns, vegetative and sexual reproduction of Episcia ...

Results: None of the covered flowers pollinated itself spontaneously and therefore
development of fruits did not take place. However, the pollination of the flowers that were
pollinated with their own pollen was successful i.e. self-compatibility is possible. The same is true
for the experiments testing on allogamy.
Discussion: The conducted experiments show that self-compatibility in Episcia lilacina is
indeed possible, but is successfully prevented by two mechanisms in their natural environment.
The first method is the curling of filaments so that the anthers are placed in the back area of the
flowers. Due to the proximity of the anthers to the stigma during this process there is a
possibility of self-pollination, which is prevented by another mechanism: The stigma stays
unreceptive till the curling of the filaments has finished. In this way it is assured that the receptive
stigma will not ever come in contact with the plants’ own pollen.
Self-pollination is not necessary, because Episcia lilacina successfully spreads vegetatively via
stolons. Additionally, selfing is seen rarely in the family of Gesneriaceae (Weber 2004).
P/O Ratio
According to Cruden (1977), the pollen-ovule ratio reflects the reproductive system. By
pollen-ovule ratio Cruden means the proportion of the pollen grain numbers as compared to the
number of ovules in a bisexual flower. A high P/O ratio suggests xenogamy, a lower one implies
autogamy to cleistogamy. He even considered that P/O ratios better reflect the breeding system
than morphological characteristics. To characterize the reproductive system of Episcia lilacina the
number of the pollen grains and the number of ovule per flower were counted.
Materials and Methods: Altogether, five buds were investigated. To be sure that the whole
amount of pollen grains was still in the anthers, the pollen grains were counted with buds shortly
before anthesis. The content of each anther was counted per hand using a stereomicroscope and
a grid.
For the determination of the number of ovules the same buds as before were used. The
gynoecium was dissected out under a stereoscope and the ovules were counted afterwards.
The pollen-ovule ratio per flower was calculated by the following formula:
P =
O
number of
number
pollen grains per flower
of ovules per flower
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