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 butterwort species
from the Andean region down to Cape Horn do not form a
winter bud during the cold winter period. 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). Also within the tropical-heterophyllous
growth type there are species that do form two distinct
sets of carnivorous summer leaves and are therefore also
anisophyllous.
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