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

Materials and Methods: Episcia lilacina has a single dorsal nectar gland. To ensure that the
gland is the only tissue, which produces nectar, it was removed. This took place before other
experiments were performed.
To make out the beginning of nectar production, the spur of the bud was opened and nectar
– if there was any - was absorbed by glass capillaries. At the beginning of the nectar production
the amount was too low to measure it.
To find out the maximum amount of secreted nectar the spur was dorsally cut open and the
nectar was removed every second hour. The measurement was not possible any longer than
several hours per flower because the flowers were very tenuous and got very easily damaged by
the glass capillaries. Furthermore the cut spur began to mortify. To remove and measure the
nectar, glass capillaries were used (0,5 µl, 1 µl and 3 µl disposable capillaries, Hirschmann
Laborgeräte, R≤ 0,5%, CV≤1,0%). In total, nectar was taken on three different days every two
hours. The removal was started at different times (11.30 p.m., 5.30 a.m., 7.45 a.m.).
Further on, at different times of the day several flowers were cut open and nectar was
removed to find out at which time the maximum was offered. Additionally, flowers in the male
and female stage were investigated if there were any differences in the maximum of produced
nectar.
Because of the small amount of nectar in a flower, the nectar of several flowers was put
together on a refractometer to measure the sugar concentration. After cutting the top of the spur
the nectar was transferred on it with glass capillaries and then the range was read. At a
temperature of 29°C two measurements on two different days were made. The flowers were
taken from two different investigation spots. The first time 16 flowers were collected near the
station. The second time 19 flowers were harvested near the “Rio Quebrada”.
Results: The flower of Episcia lilacina starts its production of nectar a couple of hours before
opening. Already at 11 p.m. of the day before nectar could be found in the spur of the flower.
The average amount of nectar produced in two hours is 0,5 µl (±0,2µl standard deviation). The
longest duration of nectar measuring was 14 hours. After these 14 hours in none of the flowers
(male or female) nectar could be measured any longer.
The maximum of nectar produced by one flower is 5,4 µl. The average value is 2 µl (±1,37 µl
standard deviation). No significant difference in nectar production during male and female stages
could be measured. The collected nectar had a sugar concentration of 27%.
Discussion: The flowers can get easily damaged by glass capillaries. The used method does
not seem be the most appropriate. As soon as the spur is cut it starts to wither, a fact that for
sure has had its influence on the nectar production.
67