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

Euglossini are a tribe within the family Apidae, which are also called orchid bees. The
proboscises of orchid bees are up to 41 mm long (Roubik and Hanson 2004). Euglossine bees
use the nectar of the flowers of Gesneriaceae as an important food resource (Endress 1994).
Butterflies do not forage on flowers with a corolla depth that exceeds their tongue length
(Corbet 2000). From that, it can be concluded that its proboscis has to be of at least equal length
as the tube. Because there is a positive relationship between body length and proboscis length in
the family of Lepidoptera (Kunte 2007), conclusions considering their size can be drawn. Thus
smaller butterfly species can be excluded from the group of possible pollinators.
Length of tube alone delivers no further indication to exclude one of the insects that are
considered possible pollinators until now.
The narrow entrance to the flower is supposed to prevent pollinators from penetrating too
deep into the inside of the flower. Additionally, the insect is positioned correctly to be brought in
contact with the pollen as well as being able to pollinate the style. During this process the pollen
is supposedly placed on its head or proboscis. It is quite interesting that the tube broadens right
after the narrow entrance significantly to almost double the size of the narrowest part before
narrowing again in the rear section. Such an expanse can also be observed with other tubular
flowers in the family of Gesneriaceae, e.g. Nauticalyx or Paradrymonia. The entrance of the flower
is alike the narrowest part of the tube because both cross-section areas differ only rarely in size.
Because of the narrowest part being located in the rear part of the flower it likely serves as
guidance for the proboscis so that it can reach the nectar.
The size of the floral display can matter in attraction of pollinators. Within most plant
species, pollinators generally select in favour of large flowers (Pellmyr 2002). The limb diameter
of averaged 42 mm forms a spacious landing area for insects. Thus the flower is almost as long as
it is wide. The attracting effect of the big limb is quite considerable.
If the sum of the length of style and height of ovary is compared to the length of stamina
approximately equal values are reached. This indicates that the stigma indeed comes to a halt on
roughly the same position that had held the anthers before. Thus the application of pollen from
the body of the pollinator on the stigma is guaranteed.
Bud Development
Before referring to the process of anthesis more exactly, the bud development shall be taken
into observation. The morphological changes in bud development and growth are described,
rather than absolute changes in bud size or stem growth, because they are more indicative of
development than mere increase in size and length.
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