Pinguicula moranensis is a perennial rosette-forming
insectivorous herb native to Mexico and Guatemala. A species of
butterwort, it forms summer rosettes of flat, succulent leaves up to
10 centimeters (4 in) long, which are covered in mucilagenous
(sticky) glands that attract, trap, and digest arthropod prey.
Nutrients derived from the prey are used to supplement the
nutrient-poor substrate that the plant grows in. In the winter the
plant forms a non-carnivorous rosette of small, fleshy leaves that
conserves energy while food and moisture supplies are low. Single
pink, purple, or violet flowers appear twice a year on upright
stalks up to 25 centimeters long.
The species was first collected by Humboldt and Bonpland on the
outskirts of Mina de Morán in the Sierra de Pachuca of the
modern-day Mexican state of Hidalgo on their Latin American
expedition of 1799–1804. Based on these collections, Humboldt,
Bonpland and Carl Sigismund Kunth described this species in Nova
Genera et Species Plantarum in 1817. The extremely variable species
has been redefined at least twice since, while several new
species have been segregated from it based on various geographical
or morphological distinctions, although the legitimacy of some of
these is still debated. P. moranensis remains the most common and
most widely distributed member of the Section Orcheosanthus. It has
long been cultivated for its carnivorous nature and attractive
flowers, and is one of the most common butterworts in cultivation.
The generic name Pinguicula is derived from the Latin pinguis
(meaning "fat") due to the buttery texture of the surface of the
carnivorous leaves. The specific epithet moranensis refers to its
type location, Mina de Moran.
P. moranensis is seasonally dimorphic, in that it undergoes two
distinct growth habits throughout the year. During the summer when
rain and insect prey are most plentiful, the plant forms a ground
hugging rosette composed of 6–8 generally obovate leaves, each up to
95 millimeters (3¾ in) long. These leaves are carnivorous, having a
large surface area densely covered with stalked mucilagenous glands
with which they attract, trap, and digest arthropod prey, most
commonly flies. These so-called "summer leaves" are replaced by
"winter rosettes" of small, glandless succulent leaves with the
onset of the dry season in October. This protective winter rosette
allows the plant to undergo winter dormancy until the first rains
begin in May. Flowers born singly on upright 10–25 centimeters (4–10
in.) peduncles emerge twice during the year (from the summer rosette
and again from the winter rosette), a feature rare among the Mexican
species. In the summer these appear in June, peak in August and
September, and disappear with the return to the winter rosette in
October or November.
Leaves and carnivory
Leaf color can be variable, even within a population. Oaxaca, Mexico
The leaf blades of the summer rosettes of P. moranensis are
smooth, rigid, and succulent, varying from bright yellow-green to
maroon in colour. The laminae are generally obovate to orbicular,
between 5.5 and 13 centimeters (2–5 in.) long and supported by a 1
to 3.5 centimetre (⅜–1 ⅜ in.) petiole.
As with all members of the genus, these leaf blades are densely
covered by peduncular (stalked) mucilagenous glands and sessile
(flat) digestive glands. The peduncular glands consist of a few
secretory cells on top of a single-celled stalk. These cells produce
a mucilagenous secretion which forms visible droplets across the
leaf surface. This wet appearance probably helps lure prey in search
of water; a similar phenomenon is observed in the sundews. The
droplets secrete only limited enzymes and serve mainly to entrap
insects. On contact with an insect, the peduncular glands release
additional mucilage from special reservoir cells located at the base
of their stalks. The insect struggles, triggering more glands and
encasing itself in mucilage. P. moranensis can bend its leaf edges
slightly by thigmotropism, bringing additional glands into contact
with the trapped insect. The sessile glands, which lie flat on the
leaf surface, serve to digest the insect prey. Once the prey is
entrapped by the peduncular glands and digestion begins, the initial
flow of nitrogen triggers enzyme release by the sessile glands.
These enzymes, which include amylase, esterase, phosphatase,
protease, and ribonuclease break down the digestible components of
the insect body. These fluids are then absorbed back into the leaf
surface through cuticular holes, leaving only the chitin exoskeleton
of the larger insects on the leaf surface.
The holes in the cuticle which allow for this digestive mechanism
pose a challenge for the plant, since they serve as breaks in the
cuticle (waxy layer) that protects the plant from desiccation.
As a result, P. moranensis is usually found in relatively humid
environments. The production of the stalked capture glands and
sessile digestive glands is also costly. A recent study found that
the density of these respective glands can be correlated to
environmental gradients. For example, capture gland density was
found to be highest where prey availability was low, whereas
digestive glands density showed direct correlation to prey
availability. These results suggest that the amount of investment in
carnivorous features is an adaptation to the environmental
An inflorescence emerging from a winter rosette
 Winter rosette
The "winter" or "resting" rosette of P. moranensis is two to
three (maximum five) centimeters (¾–2 in.) in diameter and consists
of 60 to 100 or more small, fleshy, non-glandular leaves. These are
each 10 to 30 millimeters (⅜–1 ¼ in.) long and three to eight
millimeters (⅛–5⁄16 in.) wide, generally spatulate or oblong-spatulate,
and densely covered with fine hairs. The rosette is either open or
compact and bulb-like, depending on variety (see below).
P. moranensis produces one to seven flowers during each flowering
period. These are borne singly on upright flower stalks which are
green to brown-green in color and usually, like the upper surface of
the carnivorous leaves, are densely covered in glandular hairs; the
peduncles do, in fact, trap insect prey. The peduncles are 10 to 25
centimeters (4–10 in.) long and taper from two to three millimeters
(⅛ in.) at the base to one millimeter (1⁄16 in.) at the top.
P. moranensis flower profile
The flowers themselves are composed of five petals which are
fused at one end. The throat, the portion of the flower near the
attachment point which holds the reproductive organs, is funnel
shaped, and the petals flare out from there into a five-lobed
zygomorphic corolla. The flowers 30 to 50 millimeters (1 ¼–2 in.)
long. Below the attachment point to the stem the petals are fused
into a 15–30 millimeter long spur which protrudes backwards roughly
perpendicular to the rest of the flower.
The ovary and attached pistil protrude from the top of the floral
tube near its opening, with the receptive stigma surface toward the
front. Two 1 millimeter anthers hang from recurved, 2 millimeter
filaments behind the pistil. Pollinators exiting after
collecting nectar from the spur brush against the anther,
transferring pollen to the stigma of the next flower they visit. The
flowers can last up to 10 days but will wilt once they are
pollinated. Pollinated ovaries ripen into 5 millimeter (3⁄16 in.)
dehiscent seed capsules containing numerous 1 millimeter long seeds.
The chromosome count for this species is 2n=44.
Flower form from Querétaro, Mexico
The color and morphology of the flowers of this species is
extremely variable, a source of delight to the horticulturist and
headache to the taxonomist. Some generalizations, however, can be
The corolla flares open into five lobes, two upper lobes and
three lower lobes. The upper lobes are 7–16 millimeters (¼–⅜ in.)
long by 4–9 millimeters (5⁄32–⅜ in.) wide and generally oblong,
obovate, or cuneate. The lower lobes are similarly shaped and are
7–20 millimeters (¼–¾ in.) long by 4–18 millimeters (5⁄32–¾ in.)
wide. The central lower lobe is usually slightly longer than its
neighbors. All of the petal lobes have rounded ends. The floral tube
that houses the reproductive organs and is visible at the base of
corolla lobes is white or lilac in color and 4–6 millimeters (5⁄32–¼
in.) long. The white color of the floral tube can extend to a
variable distance onto the corolla lobes, particularly in a stripe
on the lower middle lobe. The color of the corolla lobes
generally varies from pink to purple, but has been described by
collectors as being "purple, scarlet, rosy-lavender to
bluish-purple, dark pink to lavender, pinkish-purple, deep
violet-purple, dark purple, bright mauve-pink, bright purple-pink,
magenta with [white eye], [and] reddish pale with white eye." A
rare white-flowered form is also known.
Flower color and morphology can vary greatly even within a
population, an unusual feature in the species. Notice the variation
in the size and shape of the white and dark markings, as well as the
various petal shapes and sizes present. Oaxaca, Mexico.
Sergio Zamudio Ruiz, in his 2001 revision of the section
Orcheosanthus, called the identity and exact delimitation of P.
moranensis "perhaps the most difficult problem to solve within the
genus". This difficulty is due mainly to the high variability
and large geographic distribution of the species, which has given
rise to the description of many synonyms since the species was first
described nearly 200 years ago. Botanists have attempted to
delimitate the species through various morphological, ecological and
genetic methods, though to this date some debate remains as to the
placement and description of P. moranensis and its relationship to
the species to which it is closely related.
Alexander von Humboldt
 Botanical history
Prior to Alexander von Humboldt and Aimé Bonpland's Latin
American expedition in 1799–1804, only 8 Pinguicula species were
known to science — 5 from Europe, 2 from North America and P.
involuta from Peru. From 1803–1805, three additional species from
Europe and North America were described, bringing the total of known
species to 11. In 1817 Humboldt, Bonpland and Carl Sigismund
Kunth described 3 new species from their Latin American expedition:
The Peruvian P. calyptrata and the first known Mexican species: P.
macrophylla and P. moranensis. At this point no infrageneric
classification had yet been suggested.
In 1844 a French-Swiss botanist by the name of Alphonse Pyrame de
Candolle (who created the first Code of Botanical Nomenclature)
proposed a division of the genus into three sections based on floral
morphology. He placed in the section Orcheosanthus those species
with purple, deeply bilabiate corollas with 5 sub-equal lobes, a
short floral tube, and a large spur not protruding past this tube.
He included four species in this section, all of them from Mexico:
P. oblongiloba, P. orchidioides, P. caudata and P. moranensis. He
excluded P. macrophylla H.B.K. on the grounds that it was a "dubious
A print of P. caudata from Morren's work (1872)
The section Orcheosanthus grew as Charles Morren described P.
flos-mulionis in 1872, Eugene Fournier added P. sodalium in 1873 and
Sander proposed P. bakeriana in 1881. In 1879–1888, however, a
botanist by the name of William Hemsley, after studying multiple
specimens in herbariums and in culture, came to the conclusion that
all the taxa placed in the section Orcheosanthus up to that point
belonged to the same single species. Due to doubts as to the
identity of the original two species described by H.B.K., Hemsley
decided to use the name P. caudata Schltdl. for his conglomerate
species. This name has been "indiscriminately" applied to members of
the complex ever since.
 Twentieth century
When Barnhart revised the family Lentibulariaceae in 1916, he
recognized six species in the section Orcheosanthus, admitting
however that this number was likely to change as others studied the
section in the future. Sprague in 1928 proposed that the species
joined by Hemsley were probably distinct, but that they were likely
so interrelated that distinguishing between them would require
observing characteristics that were usually or always indistinct in
dried specimens. Sprague recognized eight species in the section: P.
moranensis H.B.K, P. caudata Schltdl., P. oblongiloba, P.
flos-mulionis, P. bakeriana, a P. moranensis-like P. rosei described
by Watson in 1911, and the very distinct P. gypsicola.
In 1966 Casper published the first ever monograph of the genus.
He clearly defined his taxonomic organization according to a broad
range of morphological and phenotypic characteristics. Casper
considered P. caudata, as well as various other taxa, to be a
synonyms of P. moranensis. He therefore recognized only 6 species
for the section Orcheosanthus: P. moranensis, P. gypsicola, P.
macrophylla H.B.K., P. oblongiloba, and the two recently discovered
species P. colimensis and P. cyclosecta. Since that time 14
additional species have been discovered and assigned to the section.
When Zamudio redefined the section in 1999, however, he chose to
include only 12 species, including all six of Casper's choices. P.
moranensis, therefore, remains in the section Orcheosanthus, along
with over a dozen synonyms it has inherited in its 200-year
Phylogenetic studies take into account a broad range of plant
characteristics, such as flowering time and morphology
The varying importance which different authors have placed on
various morphological characteristics when determining the taxonomy
of the genus has long made the resulting subdivision of the genus a
subject of controversy. Ruiz (2001) supported his revision of the
section Orcheosanthus with a phylogenetic analysis, using 20
morphological and phenological characteristics. In 2005, Cieslak
et al. conducted the first comprehensive phylogenetic analysis of
the entire genus Pinguicula. Using molecular data, they were able to
isolate those morphological characteristics that were synapomorphies
for various groups, providing evidence for a genetically based
taxonomic structure. Their overall results did not support the
placement of P. moranensis in the section Orcheosanthus, rather
indicating that it should be placed in the section Longitubus along
with P. laueana.
In further disagreement with Ruiz's 2001 revision of the section
Orcheosanthus, Cieslak et al.'s phylogenetic data indicated that P.
rectifolia and several unnamed taxa that had been treated as
synonyms of P. moranensis are in fact a distinct complex. They
isolated several morphological characteristics that could be used to
differentiate between the complexes, including floral spur length
(longer in P. moranensis), flower color (never with a blue tinge in
P. moranensis), and the shape of the lateral corolla lobe
(exhibiting a twist in P. rectifolia). A more thorough study
analyzing numerous P. moranensis populations and other members of
closely related taxa is needed to resolve this complex.
After extensively studying P. moranensis in habitat, Ruiz (1999)
came to the conclusion that the species could be divided into two
distinct varieties, mainly on the basis of the shape of the leaves
composing their winter (resting) rosettes:
Pinguicula moranensis Kunth in Humb., Bonpl. et Kunth. var.
This variety has open winter rosettes composed of leaves which
are spatulate in shape and have an obtuse or rounded end. It tends
to grow in limestone-based substrates.
Pinguicula moranensis Kunth in Humb., Bonpl. et Kunth. var.
This variety has a closed, bulb-like rosette of winter leaves
which are acicular (pointy) at the tip. It tends to grow on igneous
Ruiz also noted that these subspecies differed in their
preference of soil substrate. He first noted this while attempting
to find the population of plants from which Humboldt and Bonpland
had collected their type specimens in 1803. Although Ruiz was able
to find many populations of the species growing in the areas that
Humboldt and Bonpland had visited in the vicinity if Mina de Moran,
only one population, the only one growing on limestone, matched
H.B.K.'s description and their type and isotype specimens now housed
in the herbarium of the French national museum of natural history.
The other populations in the area grew on substrate of igneous
origin and more closely matched Hooker's 1846 description of P.
orchidioides. These latter plants then became the new variety, P.
moranensis ssp. neovolcanica.
Distribution and habitat
Distribution of P. moranensis in Mexico and Guatemala
P. moranensis is the most widely distributed member of the
Section Orcheosanthus. It is also the most common and widely
distributed Pinguicula species in Mexico, being found in all the
major mountain ranges except Sierra Madre Occidental and Baja
California. Locations are known from the Mexican states of
Tamaulipas, Guanajuato, Nuevo León, Campeche, Chiapas, Oaxaca,
Puebla, Distrito Federal, Veracruz, Estado de México, Querétaro, San
Luis Potosí, Morelos, Hidalgo, Guerrero, Zacatecas, Tlaxcala,
Quintana Roo, and Michoacán and the Guatemalan departments of
Huehuetenango, Quiché, San Marcos, Quetzaltenango, Totonicapan,
Solola, Chimaltenango, Baja Verapaz, Guatemala and El Progreso. Here
it grows in mountainous regions between 800 and 3200 meters
(2600–10500 ft) in altitude. Generally, the species tends to follow
sedimentary outcrops of the Cretaceous period. P. moranensis var.
neovolcanica, however, tends to grow on igneous rocks of the Eje
Volcánico Transversal.P. moranensis growing on a tree trunk in
P. moranensis most often grows in oak, pine-oak, or temperate
montane woodlands. However, its distribution penetrates into
tropical forests and xerophytic shrublands, as well as in gorges and
canyon walls with high environmental humidity. P. moranensis prefers
humid and shady environments, such as slopes by streams, gullies, or
road cuts, or among leaf litter in sandy soil high in organic
matter. Its ability to gather nutrients from the arthropod prey it
catches allows it to grow in low-nutrient environments where other
plants would usually out-compete it. As a result, it is often found
in disturbed areas or on steep cliffs or hillsides. Since its roots
do little more than provide anchorage, the plant requires little or
no soil, and dense clusters can be found clinging onto boulders,
moss or crags in rock faces, or even epiphytically on tree trunks.
Common companion plants include mosses, Selaginella, ferns and other
herbaceous plants, as well as canopy trees such as pines and oaks.
P. moranensis is one of the most popular and commonly cultivated
Pinguicula, in part due to its large size, large and pretty flowers,
and the ease with which it can be grown as a container plant. Most
growers use an open soil mix composed of some combination of washed
sand, perlite, vermiculite, peat moss, gypsum and/or decomposed
granite. Soil should be kept well drained, but watered regularly
with distilled water in the summer and only very rarely once the
plant enters its winter rosette. The species grows readily on
well-lit windowsills, under fluorescent lights, or in warm to hot
 Hybrids and cultivars
Although no natural hybrids involving P. moranensis have been
reported, the species is known to hybridize quite readily in
cultivation. As a result, a number of cultivars involving the
species have been registered and are recognized by the International
Carnivorous Plant Society.