Today
more than 100
different species are known to the genus Pinguicula.
There
exist several growth types. Distinctive
features are the formation of different
leaf types within the annual growth cycle. The different growth types
reflect adaptation of different species through evolution to different
habitats and climates.
Generally
butterwort
species can be divided into 2 groups:
The
first group is called temperate
growth type. This group is characterized by the fact that due
to cold temperatures plant growth ends with formation of a winter bud
(hibernaculum). If the plants form beside the leaves of the winter bud only one additional set of leaves during the
growing season, they belong to the temperate-heterophyllous
growth type. Whereas the generative and vegetative rosettes
consist of different leaf forms, plants belong to the temperate-anisophyllous
growth type. Very interesting is the fact that temperate
butterwort species from the Andean region down to Cape Horn do not form
a winter bud. This leads to the conclusion that they have not lost
their "tropical heritage" and suggests that the origin of Pinguicula
species was the Carribean/Mesoamerican region.
The
second group of
plants is characterized by a growth cycle the whole year around (tropical
growth type). When climate conditions do not vary a lot there
is only a formation of one single set of leaves (tropical-homophyllous
growth type). Is there a winter and summer period, plants can
form two sets of leaves. Leaves in the wet summer season have
carnivorous characteristics, while in the more dry and cool winter
period leaves are small, succulent and non-carnivorous (tropical-heterophyllous
growth type).
|