Pinguicula moranensis is a perennial rosette-forming insectivorous herb in the flowering plant family Lentibulariaceae. It is native to El Salvador, Guatemala, Honduras and Mexico. A species of butterwort, it forms summer rosettes of flat, succulent leaves up to 10 centimeters (4 in) long, which are covered in mucilaginous (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 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.Zamudio, S. 1999 Based on these collections, 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,Casper, S.J. 1966Zamudio, Sergio 2001 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.As an example, see Speta 1989. Of the three species described by Speta & Fuchs, two (P. rectifolia and P. potosiensis) were rejected as synonyms by Zamudio 2001, while P. rectifolia was supported by Ciezlak et al.'s phylogenetic study in 2005. 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 (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.
Plant characteristics
Habit Pinguicula 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 ( in) long.Alcalá, R.E. & Dominguez, C.A. 2005 These leaves are carnivorous, having a large surface area densely covered with stalked mucilaginous 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.Peduncle length: Zamudio 2001, p. 158.According to Cieslak et al. 2005, P. moctezumae, P. moranensis, P. emarginata, P. species 'Huahuapan' and P. rectifolia all share this trait.Cieslak et al., 2005 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
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 (–1 in.) petiole.Zamudio 2001, p. 158.
As with all members of the genus, these leaf blades are densely covered by peduncular (stalked) mucilaginous 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 mucilaginous 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.Legendre, L. 2000
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 gradients.
Winter rosette
The "winter" or "resting" rosette of P. moranensis is two to three (maximum five) centimeters (–2 in.) in diameter and consists of 60 to 100 or more small, fleshy, non-glandular leaves. These are each 10 to 30 millimeters (–1 in.) long and three to eight millimeters (– 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).Zamudio 2001, p. 161.
Flowers Pinguicula 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 ( in.) at the base to one millimeter ( in.) at the top.
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 –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.According to Cieslak (2005), the spur length is a diagnostic feature when differentiating this species from P. recitoflia. Cieslak asserts that in P. moranensis the spur is more than 50% longer than the rest of the corolla.
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.Legendre, L. Pollination of Pinguicula flowers. Retrieved on January 2, 2007. Pollinated ovaries ripen into 5 millimeter ( in.) dehiscent seed capsules containing numerous 1 millimeter long seeds. The chromosome count for this species is 2n=44.Zamudio 2001, p. 60.
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 made.
The corolla flares open into five lobes, two upper lobes and three lower lobes. The upper lobes are 7–16 millimeters (– in.) long by 4–9 millimeters (– in.) wide and generally oblong, obovate, or cuneate. The lower lobes are similarly shaped and are 7–20 millimeters (– in.) long by 4–18 millimeters (– 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 (– 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."Zamudio 2001, p. 184. A rare white-flowered form is also known.
Taxonomy 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".Zamudio 2001, p. 26; "La identidad de Pinguicula moranensis y su delimitación precisa es quizás el problema más difÍcil de resolver dentro del género." 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.
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 to 1805, three additional species from Europe and North America were described, bringing the total of known species to 11. In 1817, Carl Sigismund Kunth described 3 new species from Alexander von Humboldt and Aimé Bonpland's Latin American expedition: The Peruvian P. calyptrata and the first known Mexican species: P. macrophylla and P. moranensis.From Zamudio 2001, orig. Humboldt, A., A. Bonpland & C.S. Kunth. 1817 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 species".From Zamudio 2001, orig. A.P. De Candolle 1844