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

Discussion: A fruit set of 19% seems quite low with regard to the fruit set of Paraboa rufescens
(Gesneriaceae) of about 40% (Gao et al 2006) and the fruit set of Cyrtandra grandiflora
(Gesneriaceae) of 32-39% (Roelofs 1979). Even though no legitimate pollinator could be
observed, pollination did occur without a doubt. The only regular visitor was a species of
Meliponinae. Due to SanMartin-Gajardo & Sazima (2004) pollen collectors can act as pollinators
even if they are not the legitimate pollinator. Either the pollinator just could not be encountered
during the observation period or it was deterred by the presence of the observer. However, selfpollination
can be excluded to explain the fruit set results (see below in „pollination in the field“).
The observed fruit set is most likely caused by the visitation of meliponine bees. The stingless
bee touched the stigma in search of pollen and thus pollinated the flower in case it had visited a
flower in the male stage before. There are a lot of flowers that show a special floral syndrome but
are visited by pollinators that do not fit. Waser and Price (1990) quote Delphinium nelsonii as an
example, whose blue asymmetrical flowers conform to a bee syndrome, but attract humming
birds along with hawkmoths, solitary bees, and several species of bumblebees.
Pollination Experiments
The anatomy of the flower as well as proterandry decreases the possibility of self-pollination
enormously. Therefore, different pollination experiments were performed to investigate if
spontaneous self-pollination occurs or if manual self-pollination is possible.
Materials and Methods: To test spontaneous self-pollination, on the day before the buds
opened they were bagged. The bag remained until the anthesis of the flowers had ended.
Afterwards the development of fruits was checked and documented.
To test self-compatibility, the anthers were cut out from the flower during the male stage.
The anthers were put into a container. On the following day, the pollen was transferred to the
stigma of the same flower. From the beginning the flower was covered with a bag to protect it
against flower visitors. After the end of the anthesis the bag was removed and the following
development was documented and photos were taken.
To ensure that cross-pollination (allogamy) is possible, pollen of a different flower must be
used for pollination. After the opening of the flower the anthers were cut out. Afterwards the
flowers were covered to prevent visits of pollinators. During the female stage the stigma was
pollinated with pollen from a different plant. The flower was covered again. In the following days
the fruit set was observed and documented.
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