Abstract:
Monochoria vaginalis (Burm.f.) Presl and Monochoria hastata (L.) Solms-Laub. are both known
by the common name ‘Diya habarala’ in Sinhala (Pontederiaceae). Diya habarala is a medicinal
plant used as a remedy for many illnesses and, no distinction is made between the two species. A
recent morphometric analysis recognised three phenetic groups within M. vaginalis and an
interesting character that was recorded in one of these phenetic groups was the presence of red
colour glands in the sub-palisade layer that gave a rough texture to the leaf lamina. These
phenetic groups were also supported by molecular and phytochemical data. Splitting of taxa into
new species should be based on many evidences which in turn would help in creating a stable
entity. The present study was conducted with the aim of collecting leaf anatomical evidence in
support of recognizing the taxonomic position of the phenetic groups identified within M.
vaginalis. Both free hand and microtome sections of fresh leaves representing the three phenetic
groups of M. vaginalis (1, 2 and 3 respectively) and M. hastata were examined under the light
microscope. Characters showing variation among the groups; presence and abundance of red
colour glands in the sub-palisade layer; triangle shaped, transparent, enlarged cells in between
palisade layer and, raphides and styloids were recorded. Red colour glands were present only in
the phenetic group 2 and 3, where the abundance was higher in the group 3 (2-3 glands/view
under the mid power); triangle shaped, transparent, enlarged cells were present in all where it
was less abundant in M. hastata and M. vaginalis group 1 (7-9 cells/view under the mid power)
while they were high in group 2 and 3 (14-16 cells and 12-14 cells/view under the mid power
respectively). Styloids were present only in M. hastata while raphides occurred in all but in high
abundance in M. hastata and low in all groups of M. vaginalis. Absence of glands and presence
of styloids separates M. hastata from the M. vaginalis. Within M. vaginalis, the absence of
glands and less abundance of triangular cells separates the group 1 from both 2 and 3. Even
though the occurrence of glands and triangular cells between the group 2 and 3 differ, both
groups could be considered as possessing a similar leaf anatomy. This data would be of value
during species limit determination of the three phenetic groups of M. vaginalis.
