Wright ex Grisebach (1866)
southwestern part of Cuba's main island in the Pinar del
Rio province and in the northern region of the Isla de
la Juventud there are swampy areas at sea level which
are called "sabanas arenosas", home of P. filifolia
ssp. filifolia. Plants grow there in open areas
between grasses and beside small palms and pine trees.
Plants are growing in full sun light only slightly
shaded by the neighboring grasses. The moist upper layer
of the soil consists of fine white quartz sand, while
the soil layer underneath has a high percentage of
organic matter. The high solar radiation is even
intensified by the reflection of the sunlight through
the white sand particles. Air humidity is high all year
around, although the local climate has a wet and a
dry season. During the rainy season temperatures are in
a range between 25 and 28 °C (with night temperatures
not dropping below 10 °C), while during the dry season
it is hotter with maximum temperatures between 30 and 35
°C during daytime. The dry season ranges from January
until April. The life cycle of the plants seem to be
highly impacted by the local climatic conditions. During
the dry season plants are normally dying and therefore
the species is mostly annual. After the first higher
precipitations seeds germinate quickly and new plants
are growing. Only in 2014 there was a new subspecies
described from an isolated area in the northwestern part
of the Pinar del Rio province. Due to the solely white
colour of the corolla lobes the subspecies was named P.
filifolia ssp. alba. Plants of the
new subspecies also differs from P. filifolia
ssp. filifolia by their shorter leaves, by their
higher number of flowers per plant, by their shorter and
broader spur and by their smaller seed capsules.
studies have shown, that during the juvenile stage P.
filifolia first forms spathulate leaves, only up
to 3 mm long with a rounded apex, that lie in form of a
rosette close to the soil. Only afterwards the typical
long, fine upright leaves do occur (from which the latin
species name "filifolia" is derived from). These
yellowish-green leaves can up to 20 cm and are densely
covered with glandular hairs. At first sight the plants
resemble the North American sundew species Drosera
of P. filifolia starts in the middle of the
rainy season end of July or beginning of August. While P.
filifolia ssp. filifolia forms between 2
and 3 flower scapes, for P. filifolia ssp. alba
a number of 6 to 8 flowers per plant is more typical.
The flower scapes can get ever larger than the leaves.
The corolla lobes are of equal size, but can vary in
form from broadly obovate to more spathulate. While the
colour of the corolla lobes with P. filifolia
ssp. filifolia vary between white, pale violet,
pink and blueish (rarely there have even yellow corollas
observed), the colour of the corolla lobes of P.
filifolia ssp. alba are only white.
The cylindrical corolla tube is of yellow or violet
colour, slightly bent towards the end and covered with
brownish or violett parallel running veins. The
spur is subcylindrical and gets bigger towards the apex.
To obtain seed a pollinator is needed, as in cultivation
without the presence of insects there were never any
cultivation of this species under Central European
conditions seems to be very difficult. The requirements
of high solar radiation, hight humidity and tropical
temperatures are difficult to simulate. A good aeration
of the plants impacts plant health significantly. Under
more suboptimal cultivation conditions plants tend to
reduce its size continuously and finally rot. A
cultivation in pure peat seems possible, but special
care has to be take that no larvae of fungus gnats do
develop in the soil, as the larvae also eat on the roots
of the plants, that could lead to fungus infection of
the roots and the plants.