Carnivorous Plants/Insectivorous Plants in the Wilderness

The idea that some plants are carnivorous may sound strange. Plants are eaten by herbivores and herbivores, in turn, are eaten by carnivores - a hierarchy of the food chain. History shows that there was some resistance on the part of early botanists to accept the notion that some plants had indeed evolved to catch and digest animals for their nutritional needs. There are places in the world where the soil is poor and plants cannot obtain enough nutrients through the root to sustain their growth. This environmental stress has given rise to a habit quite eccentric in the plant kingdom of our planet. It is in such mineral-poor environments that the plants that have adopted carnivory can be found. There are some 760 species of carnivorous plants recognized today, representing 12 families of angiosperm classification.

The family Bromeliaceae contains some 50 genera. Three species, two in Brocchinia and one in Catopsis, have recently been recognized as carnivorous (Brocchinia reducta, Brocchinia hectioides and Catopsis berteroniana) It is quite conceivable that the list of carnivorous bromeliads will get longer.

The tightly overlapping leaf bases form a tank that retains water. The upper portion of the leaf is waxy to cause the insect to lose its foothold and fall. Both adaxial (upper) and abaxial (lower) surfaces of the lower portion of the leaf are capable of absorbing nutrients. Unlike typical bromeliads, Brocchinia grows in a wet, acidic soil in full sun. The leaves of B. reducta assume a light yellow color in their native Guiana Highlands. The larger of the two, Brocchinia hectioides, grows to 2 m in height.

Catopsis contains 25 species. One species, C. berteroniana, has been shown to exhibit a primitive carnivorous habit.

Paepalanthus is a large genus containing some 600 species mainly from South America, of which only one, P. bromelioides, has recently been recognized as a primitive carnivore by Figueira, et al. (1994), the latest addition to our growing list of carnivorous angiosperms. There are reports of other species in the genus exhibiting similar characteristics.

The plant is a monocot native to Brazil, only found in Cipo National Park, at an elevation of 800-1200 m, in the state of Minas Gerais. The plant radiates long, flat leaves from a short stem. As in Brocchinia, its tightly overlapping leaves create a tank at the rosette center, retaining some acidic water. Ultraviolet attraction of the leaf is suspected to allure prey. Insects fall in the liquid and get digested. There is no report of enzyme secretions by the plant, but the glands exist on the leaf surface that allow the absorption of the product of digestion by bacteria.

General

Glistening in the sun like a cluster of diamonds, with their dew-covered leaves emanating the full spectrum of the rainbow, the name "sundew" aptly describes the beauty of these carnivorous plants that use a "flypaper" or adhesive trap to catch small animal prey. The genus name Drosera is derived from a Greek word droseros for "dewy". Sundews typically grow on the moist surface of bogs and marshy savannas, often creating a large patch of shining red carpet.

Probably the most famous of all carnivorous plants because of its swift movement of trap leaves, the Venus flytrap is endemic to the Atlantic coastal plain of North America, where it is highly localized to southeastern North Carolina and the adjacent northeastern South Carolina within a 100km radius around the city of Wilmington on the N.C. coast.

GENERAL

First discovered in India by Plukenet in 1696, the plant was formally described as Aldrovanda vesiculosa by Linnaeus in 1753 (Lloyd). The plant is commonly referred to as the waterwheel plant, and is the only extant cousin of the terrestrial Venus flytrap. The monotypic genus Aldrovanda belongs to the sundew family Droseraceae. Historical records show a wide distribution throughout the Old World, including much of Europe, Africa, India, Japan and Australia, but none, curiously, in the New World, where the Venus flytrap occurs. Recent molecular analysis has confirmed a close relationship between Dionaea and Aldrovanda (traditionally held view). It is also revealed that these two form a sister clade to Drosera.

PLANT

Aldrovanda is a small fresh water plant and is entirely rootless. It floats just below the water surface. The stem, anywhere from 5 to 25 cm long, continues to grow at the apex on one end, as the other, older end withers (dies) away. The stem has a series of whorls about 2 cm across at every 10 mm or so interval. Each whorl normally comprises 7-8 arms (sometimes 5, 6 or 9) radiating from the stem. Each arm represents one leaf with a thin, broad petiole that bears a trap at the tip. Morphologically, the trap is a leaf blade. There also grow 4-6 bristles around the trap, supposedly protecting the trap from floating debris. The bristles are not lobes nor appendages but emergences (Lloyd). The trap is quite similar to that of a Venus flytrap in appearance and structure as well as in function. A whole plant, including the trap portion, is green, suggesting photosynthesis takes place. At the height of the growing season, the stem may branch out, then break, producing a new plant. On one summer day in Hanyu, Japan, Shimizu (1966) counted 89 whorls in one plant, with 4 branching stems, totaling 52 cm in length.

The trap, corresponding to the leaf blade, is twisted to the left about its midrib almost 80 degrees, and then the midrib of the trap is bent to the right 60 degrees. The end result of this seemingly convoluted geometric manipulations of trap posture is that each set of traps in a given whorl more or less radially face outwards. The trap portion, which is barely 5 mm long, is almost translucent and appears like a miniature clamshell. Each lobe has numerous tiny teeth along the slightly folded-in margin. When the trap is set, the lobes are wide open, waiting for an unsuspecting prey to stop by.

Each lobe is divided into two zones: The marginal zone and the central zone. Each zone is further divided into 3 regions.

The marginal zone is very thin, formed of two layers of cells except at the rim. The outer region (the rim) is composed of one line of cells having a short tooth-like projection. This forms miniature teeth along the trap margin. The quadrifid region below is where many quadrifid glands are found buried on the inner surface. The outer surface bears small er, normally two-armed, glands. Further below is the hairless region where only two-armed glands (bifids) are found on the outer surface.

The central zone, thicker than the marginal zone, is three-cell layered and forms the digestive cavity during the narrowing phase. The digestive region is where numerous small sessile glands are found on the inner surface along with 15 or so thin trigger hairs scattered among the glands. Two-armed glands are found on the outer surface. Next comes the detention region, showing no glands. Finally, the midrib region has many digestive glands and several more trigger hairs.

TRAP OPERATION

When a trigger hair is touched, the trap shuts. A single mechanical stimulus to any of its many trigger hairs will cause rapid and instantaneous trap closure in a young trap, while two or more stimuli are often needed in older traps. As in Dionaea, trap closure proceeds in two phases: The initial rapid closure, followed by the slower narrowing phase. When the trap closes in response to stimulus, the rim of each lobe comes in contact with each other, or nearly so, with the minute teeth along the rim interlocking slightly. This happens in such a speed in the water (1/60 sec) that the whole plant shivers. This leaves some space for the prey to move around within the trap cavity. If it was a false alarm, the trap reopens usually in a matter of an hour. Continued stimulation by the trapped prey causes the narrowing phase to begin, which lasts for several minutes. This brings the lobes more closely, forming a tight seal. This reduces the cavity space, shifting it to the digestive region (within the central zone) toward the midrib. The digestive process starts with the secretions of digestive liquid into the cavity. The quadrifids on the marginal zone may contribute to the pumping of water out of the space between lobe margins, thus further securing the tight seal during the digestive process. When the digestion is over, the trap reopens, first by swelling, and then parting the lobes.

INFLORESCENCE

In high summer, a single flower is borne on a short stalk protruding just above the water surface. A flower stalk is produced ,usually near the apex, at the node of one of many whorls along the stem. The whorl where the flower stalk is attached often (but not always) lacks all or some of the traps at the petiole tips. It is probably due to plant's energy being diverted to flower production. The flower is merely 5 mm across, with five white petals with a slight tint of green, with five sepals. Five stamens surround an ovary. In Aldrovanda flowers are rare. Even in a vigorous stand of numerous whorl-carrying stems covering the water surface, only a limited number of stems produce a flower. In a temperate habitat the flower opens on a hot summer day and only for a few hours around 11am to 2pm.

When the water temperature drops below 17 degrees (C), the plant forms a hibernaculum and stays dormant during cold months. Aldrovanda is a tropical plant, but its ability to form a resting bud has allowed it to expand its distribution over temperate zones. A winter bud, measuring 10 mm or so, is formed at the apex at the end of summer in a temperate habitat. As the ice forms over the water surface, the bud sinks at the lake floor to protect itself and remains dormant. As the water warms in spring, the bud floats to the surface, and starts to expand. In tropical regions where water remains warm, the plant continues to grow throughout the year.

The tropical pitcher plants, Nepenthes, are climbing vines. Each leaf has a long tendril, at the tip of which develops a pitcher that retains some liquid to catch small animals. Generally, invertebrates are main prey for Nepenthes traps.

The pitchers come in astonishing varieties of shapes and colors. Some produce a pitcher of huge size capable of holding -x- liters of water. Occasionally, frogs and small lizards are reported to have been found in the liquid of such pitchers. There are some incidents of a bird captured in the pitcher in the wild. This makes Nepenthes the indisputable winner among all carnivorous plants for prey size category. These are events of serendipity, however, and the majority of prey consists of insects and other bugs.

Insects are attracted to the pitcher by combination of scents, color and nectar (Clarke). The prey falls into the pool of digestive liquid and drowns. As the insect's body decomposes, the digested materials are absorbed through the pitcher walls and used for growth and reproduction. The plants gain essential nutrients from the trapped animal that are deficient or lacking in the soils they grow in.

A recorded history of Nepenthes dates back to 1658 in French Madagascar. Colonial governor Etienne de Flacourt (appointed by the French East India Company) described a pitcher plant in Histoire de la Grande Isle de Madagascar under the local name "Amramitico". The species was later formally described as N. madagascariensis by J. L. M. Poiret in 1799. (Lloyd 1942, Kusakabe 1961, Kurata 1976).

In 1682, a Swedish physician, H. N. Grimm, in Ceylon (now Sri Lanka) reported a local pitcher plant from the island, which was later described as N. distillatoria by Carolus Linnaeus in 1753 (Kusakabe 1961, Kurata 1976).

The genus Nepenthes comprises some 94 species most occurring in the tropics of Southeast Asia. Sumatra, Malay Peninsular, Java and Borneo collectively support 52 endemic species (Clarke). The high degree of endemism in the region suggests the origin of the genus centers around Borneo (Juniper), with the island of Borneo alone containing 31 species, followed by Sumatra counting 29 species (Clarke). The secondary center of diversity includes the islands of New Guinea, Sulawesi and Mindanao as well as Peninsular Malaysia (Clarke)

The total distribution of the genus extends westward to the isolated population of N. khasiana in Assam (India), N. distillatoria in Sri Lanka, N. pervillei in the Seychelles, and to Madagascar with two species N. madagascariensis and N. masoalensis (Juniper et al). Eastward it reaches New Caledonia where N. vieillardii is found (Kurata).

The plants grow in nutrient-poor soils which are generally acidic and constantly wet. Nepenthes are not jungle plants (Kurata) and in general seem to have a low tolerance of shade (Juniper, et al). The plants climb among trees and shrubs or trail along the ground if there is no adjacent vegetation. (Clark). In Borneo, Nepenthes is found from sea level to 3500 m. Some inhabit in bogs, while some climb to a tall tree growing several meters (Clarke).

Nepenthes species can be divided into two groups for their habitat preference: 1) Lowlands (at altitudes less than 1000 meters) characterized by high temperature and humidity all day and 2) highlands (above 1000 meters) having a climate of cooler temperature at night and wetter in general, often covered with thick cloud, supporting moss growth (Kurata). Some highland species are epiphytes.

A Nepenthes plant produces two types of pitchers at different stages of its life. When young, the plant forms a rosette of leaves, with a relatively short stem. The pitchers produced in this stage are referred to as the "lower" or "terrestrial" pitcher. After a few years, as the plant grows more mature, the internode begins to elongate, and the plant enters the climbing stage. The pitchers change to what is referred to as the “upper” or “aerial” pitcher. Sometimes during this transition from a rosette to climbing form, a pitcher of an intermediate shape may appear.

The upper and lower pitchers within a given species can be so dramatically different in appearance that taxonomic confusion might arise, as it did in the past, with the same species being erroneously recorded as two different taxa. In cultivation, experience shows that cuttings obtained from a mature plant revert back to a juvenile stage in which the lower pitchers are produced.

Lower (or Terrestrial) Pitcher: The lower pitchers are produced in a younger plant forming a rosette. The pitcher typically looks globose in shape, and often rests on the ground. There are two parallel wings running vertically on the front of the pitcher exterior. This pair of often fringed wings serves as a ladder for crawling insects, leading the potential prey to the pitcher opening where nectar is served.

The pitcher bottom abruptly changes to a slender tendril that often grows from the frontal base of the pitcher. This often (but not always) orients the lower pitchers toward the rosette center.

Upper (or Aerial) Pitcher: The upper pitchers are usually slimmer, often funnel-like, with a wider opening at the top. The wings on the pitcher front are lacking or greatly reduced. The tendril is longer, and often forms a loop during its development in an attempt to clamp neighboring vegetation (like a tree branch). If successful, this helps alleviate the weight of the water-filled pitcher from the climbing stem, and at the same time, renders support to the plant in its ascent toward the tree canopy. The aerial pitcher usually contains much less liquid than the terrestrial counterpart.

The transition to the connecting tendril is more gradual in the upper pitcher. The pitcher bottom narrows as it turns toward the back of the pitcher and finally becomes a hanging tendril. The pitcher opening tends to face away from the stem.

In some species, a la N. ampullaria, the aerial pitcher production appears to have been abandoned altogether in a climbing plant, unless firm coiling is secured by the tendril. (See Clarke's picture of immature upper pitchers).

As a new leaf continues to develop, a slender tendril grows longer. The tendril has a tiny, hairy tip which gradually swells and, in a month or so, develops into a pitcher. The lid is tightly sealed until the pitcher has fully grown. An unopened pitcher already contains sterile liquid. When the lid opens, the trap is ready. The pitcher is filled with enough liquid to drown the victim.

In terms of leaf morphology, the appearance of a Nepenthes leaf presents some confusion. In Nepenthes, what appears to be a normal leaf blade is indeed the base of the leaf. The long tendril is an extended midrib, and the pitcher represents the true lamina (leaf blade). The leaf base has been greatly broadened to make up for the inadequate photosynthesis due to the color and form of the pitcher.

Lid: All pitchers have a flat structure called the lid that overhangs the pitcher opening. In many species, the lid prevents rainwater from diluting or overflowing the liquid inside, though in some, the size and almost vertical posture of the lid fail to offer any effective shield from rain. The main purpose of the lid appears to be attraction of prey. The lid contains scattered nectar glands (particularly) on the undersurface and serves to allure potential prey to the pitcher.

Some species have a small , bulged structure near the lid base on the undersurface of the lid. This is called the glandular crest. The specific purpose of it, besides having numerous nectar glands, is not known.

In most species, at the base of the lid grows a small , filiform structure called the spur. In terms of the pitcher leaf development, the spur represents the true apex (tip) of the Nepenthes leaf (Lloyd, Clarke). A true function of the spur, if any, is not known.

Peristome: The edge of the mouth of the pitcher is surrounded with a ridge of hardened tissues called the peristome. It consists of a series of ribs (quite similar in appearance to the mouth of a Cephalotus pitcher). On the inner side of the pitcher, each rib ends in a sharp, pointed tooth, aiming toward the pitcher bottom. The large nectar glands lie underneath the teeth along the inner pitcher mouth. Visiting insects are forced to lean over in a precarious position on the slippery peristome surface. In their attempt to lick the nectar hidden behind the teeth, many fall into the depths of the pitcher.

Pitcher Zoning: Right below the peristome extends the inner walls of slippery surface covered with fine wax fragments. As the insect tries to scale the wall, wax peals off, causing the insect to lose its foothold. This waxy coating continues half way down into the pitcher. (conductive and retentive zone) Further down in the lower portion of the pitcher, the walls are lined with numerous digestive glands. The pitcher liquid usually covers this area.

A microscopic image reveals... Slippery -gland - see microscope picture. (Kurata, Juniper et al)

Researchers have succeeded in isolating the enzymes secreted by Nepenthes using unopened pitchers. Some enzymes are found to act optimally in the high acidity level of pH 2-3. Glands secrete acids and digestive enzymes. The pitcher liquid shows the highest acidity in a recently opened pitcher, and the acidity level declines as the pitcher ages. This seems to suggest that the active digestion takes place in the pitcher using the plant's own enzymes, at least when the pitcher is young.

The pitcher liquid of Nepenthes is long known to be teemed with a multitude of commensal organisms, such as larvae of mosquitoes and flies, along with other micro-organisms. Forming a miniature ecosystem within the deadly pool of digestive juices, these organisms can thrive in the liquid and readily attack drowning insects as they fall into the pitcher. These commensals are likely to play a major role in the overall digestion sequence in the Nepenthes pitcher, particularly in the older pitchers.

The surface tension of the pitcher liquid is measured to be markedly lower than that of normal water. This promotes swift drowning of an insect by acting as the wetting agent to the otherwise water-resistant insect body.

The glands absorb the products of digestion. Unlike the indiscriminate absorption from the leaf surface as in Drosera and Pinguicula, Nepenthes pitcher selectively takes in particular amino-acid and other ions. This discriminatory absorption pattern is likened to what happens in the root system, suggesting the pitcher serves to simulate the function of a real root.

Observations also show that the pitcher normally maintains a constant liquid level. It means that the pitcher is capable of regulating the amount of water by absorbing excess water (after rains) and replenishing the lost water when necessary.

The flowers of Nepenthes are rather simple in structure. Many small flowers are borne on a long flower stalk. Inflorescences are either raceme or panicle. (See illustration on inflorescence types). Flowering generally occurs on mature plants that have entered the climbing stage bearing aerial pitchers.

The genus Nepenthes is dioecious, with each individual plant only producing either male or female flowers. With the exception of bromeliads, Nepenthes is the only genus exhibiting dioecism among carnivorous plants. Both male and female flowers have four sepals and no petals. In the male flower, a single column supports crowded anthers at the apex. The female flower has an ellipsoid ovary divided into four chambers, with four stigma tips. It is noted that male inflorescences generally bear more flowers than females (Clarke), often twice as many. The glands on the sepal on both male and female flowers produce a copious amount of nectar that accumulates on the concave sepal surface.

POLLINATORS

Insects are considered the main pollinators of Nepenthes flowers. Based on limited field reports, flies and moths appear to be generalist pollinators most often seen visiting Nepenthes. They are, however, only infrequently observed. There is a speculation that Nepenthes flowers are in transition to wind-pollination.

SEEDS / Germination

Wind-dispersal …. Germination – dicot – seedling has a tiny pitcher......
Ontogeny - A pitcher is formed as the abaxial side of the midrib expands -- see seedlings

GENERAL

Known as the Dewy Pine, Drosophyllum lustanicum is the only species in the monotypic genus Drosophyllum. Once considered a member of the sundew family Droseraceae, recent molecular evidence strongly favors placement in its own family Drosophyllaceae. Molecular analysis also suggests close affiliation with Nepenthes and Triphyophyllum, both speculated to have derived from the common ancestor with Drosera.

Drosophyllum is endemic to the southwestern European Mediterranean coast. The plants grow along the Atlantic coast of Portugal, and in small regions in southern Spain and the northern tip of Morocco across the Straits of Gibraltar.

PLANT

The plant is a woody shrub that can grow to a height of 1 m or more. Thick, branching, woody stems carry slender, narrow, tapering leaf (light green) filiform ? leaves lined with numerous stalked glands covered with sticky mucilage. Unlike sundews, neither the stalked glands nor the leaf exhibit any motion during prey trapping. The glandular leaf, reaching 25 cm long, has a deep furrow along its length

A leaf has a groove along its length (M - length-wise groove) on the abaxial (lower) surface.
Deeply furrowed along its length
The leaf is linear with a deep furrow along the upper side (Juniper)

The leaf is produced twisted 180 degrees, resulting in a reverse circination of the rolled leaf as it emerges from the growth point. The length-wise furrow is formed on the abaxial (lower) surface of the leaf. The stalked glands grow on the adaxial (upper) surface as well as on both sides of the almost cylindrical leaf. Because of this arrangement, the stalked glands tend to face away from the plant center.

Unlike most species of carnivorous plants that inhabit wet, acidic soil, Drosophyllum is an exception for its choice of habitat. It is typically found in dry, sandy gravel of alkaline soil. The Mediterranean climate creates wet winters and warm-to-cool, dry summers. The coastal early morning mist in summer provides necessary moisture to the plants. It is speculated that the mucilage over the stalked glands effectively absorbs the water vapor from the moist air, providing the plants with needed moisture.

The plant is believed to produce a chemical to inhibit the growth of other plants nearby - a mechanism used by some desert plants to avoid competition for the limited water resource.

GLANDS

The mucilage secretions in Drosophyllum does not seem to be significantly different from that of Drosera, except that it is more acidic, in the range of pH 2.5-3.0, compared to pH 5.0 for Drosera and pH 3.5-4.5 for Triphyophyllum (Juniper et al.). Drosophylum (like Pinguicula and Drosera) has sessile glands for digestion on their leaf surface in addition to the stalked mucilage glands. Sessile glands are dry until stimulated. In Drosophyllum, the stalked glands also secrete digestive fluids. The glands are brilliant red against the light green leaf surface.

GENERAL

Triphyophyllum peltatum is a tropical liana endemic to a limited area of West Africa. Discovered by A. Chevalier in 1907 in Ivory Coast and originally described as Ouratea glomerata, the plant is now known from Sierra Leone, Liberia and Ivory Coast (Juniper, et al.). Airy-Show (1951) described the plant in detail noting the similarity between Triphyophyllum and Drosophyllum in their glandular leaf structure, but without any mention of carnivorous habit. In 1979, Green et al. published a paper firmly establishing its carnivorous nature based on the field observations and laboratory research at Kew (Juniper et al.). Triphyophyllum belongs to the family Dioncophyllaceae that contains two other genera, Habropetalum and Dioncophyllum, neither of which are known to be carnivorous.

Triphyophyllum grows in a rain forest, in a relatively dense shade. The soil in general is nutrient-deficient, and the habitat climate is described as six months of dry season (November to May) followed by peak rainfall in July-August. The well-rooted liana, by far, is the largest carnivorous plant known, reportedly growing up to 40 m in length. In its native habitat, the plant is observed to be growing in company of other carnivorous plants such as several species of Utricularia, Drosera indica and Genlisea africana. These species survive the dry season as seeds or in a dormant form (Juniper et al.).

The plant produces three different types of leaves, as reflected in its genus name. In its juvenile stage, the plant produces a rosette of conventional leaves from a short stem. The carnivorous glandular leaves develop only in the plant around 40-50 cm high. Further, the carnivorous leaves are produced only for several weeks just before the onset of the rainy season (May-August).

Once the plant reaches a height of 50 cm or more, the glandular leaves are no longer produced, and the plant enters the adult phase of its lifecycle. The internodes start to elongate and the third form of leaves emerge, which are oval and wavy and have two hooks at the extension of the midrib. The plant starts to grow rapidly, climbing high into the jungle canopy, using its hooked leaves to cling on to other vegetation. The adult liana is a great climber, somewhat resembling Nepenthes.

Interestingly, the cutting from the adult specimen is said to revert to the juvenile stage and the plant starts producing carnivorous glandular leaves again. The same rejuvenation phenomenon is seen in Nepenthes cuttings in cultivation in relation to their dimorphic (upper and lower) pitchers.

The carnivorous glandular leaf is almost cylindrical and the whole surface is covered with stalked glands. The flat blade is reduced or absent, and the carnivorous leaf, measuring 15-25 cm long, grows almost vertically from the rosette center. The general appearance of the glandular leaf very much resembles that of Drosophyllum. The stalked glands are of two sorts: short and long ones, being up to 3 mm long. There also exist numerous sessile glands on the leaf surface. The glandular leaf unfolds with a reverse circination, as in Drosophyllum. The glandular leaves survive only for a few weeks before being shed.

GLANDS

The structure of the glands is almost identical to that of Drosera except the size (Juniper). As in Drosophyllum, the stalked glands do not show any movement during prey capture. Also, as in Drosophyllum, the sessile glands remain dry until stimulated. Stimulation of the stalked glands increases the mucilage secretions and at the same time initiates digestive secretions from the sessile glands. Both stalked and sessile glands have a strong red coloration that contrasts sharply against green leaf surface.

2006-11-23 Description Illustration Map Species Photography

GENERAL

The genus Cephalotus is monotypic containing Cephalotus follicularis. Commonly known as the Albany pitcher plant or Western Australian pitcher plant, this unusual-looking, hairy, compact plant with exquisitely constructed pitchers is a little darling of all carnivorous plants. First collected by Archibald Menzies during the Vancouver Expedition in 1791 (Lloyd), the natural distribution of the species is confined to narrow coastal stretches around Albany all the way westwards to Augusta in the extreme southwestern tip of Western Australia. The plant is ever-green and grows in dump, peaty soil, often in company of other carnivorous plants in the region such as sundews and bladderworts. The general climate of the habitat is described as cool, wet winters and warm, dry summers. Drizzles and nightly dews provide enough moisture to the plants during the dry summer months.

PLANT

The plant produces two types of leaves, carnivorous pitcher leaves and conventional non-carnivorous foliage, both emerging from the short stem. An intermediate leaf form is sometimes observed. A mature plant forms a rosette of several centimeters in diameter. A pitcher is normally 5 cm or less in height and is attached to a long, cylindrical petiole. Some "giant" form is known that produces a pitcher almost twice as large. Roots are thick and branching with fibrous hairs. Underlying rhizomes often produce a new plant, forming a large cluster of plants in the wild.

NORMAL LEAF Conventional leaves are produced in spring. A green, flat, glossy leaf is oval-shaped, typically measuring 3 cm or so. The leaf is hairy around the rim as well as along the veins on the leaf. These conventional, photosynthetic leaves tend to stay close to the rosette center. They remain green and last for the whole year.

PITCHER LEAF As summer approaches, pitcher production begins, in tandem with the insect population growth. A slender petiole grows from the rosette center, that has a tiny, hairy blob at the tip, which gradually swells to become a pitcher. As the pitcher grows bigger, the petiole continues to elongate, often past the conventional leaves. The pitcher, now nearing the mature size, rests on the ground in a slightly slanted posture. In a day or so, the lid opens, and the trap is ready for prey acquisition. The pitcher already contains a small quantity of liquid at the base. Connected to the petiole at the neck, the pitcher always faces outward from the rosette center.

PITCHER DETAIL

The pitcher exterior has a ridge lined with hairs and nectar glands on the frontal center. Two more ridges are provided, one on each side of the globose pitcher, slanted toward the frontal opening. These ridges serve as baited ladders for crawling insects leading to the pitcher orifice.

The mouth has a well-developed rim which is strongly ribbed. Each of the 20 or so ribs terminates in a sharp, downward-pointing tooth (jaw) toward the pitcher bottom. The nectar production is heaviest just beneath these teeth. This is where insects lean over for the final and fatal attempt to get a better lick.

Right below the sharp teeth along the rim forms the thick collar overhanging the pitcher bottom. This slightly narrows the pitcher opening. The surface of the collar is lined with short downward-pointing hairs (See Juniper photo), creating an impossible-to-climb vertical wall. The collar ends abruptly with a sharp edge pointing downward, creating additional barrier to escape from the pitcher cavity.

GLANDS

Cephalotus is known to possess two kinds of glands (small and large) presumably having different functions. Toward the pitcher bottom on each side of the inner surface is a kidney-shaped brown patch, where the larger digestive glands are found. The small er glands are scattered over much of the pitcher interior below the collar.

LID

The circular lid overhangs the pitcher opening, preventing the rain water from diluting the liquid within. The lid normally rests at 45 degrees or so at the mouth. It is lined with white, translucent streaks toward the free edge. These fenestrations help to light up the otherwise somewhat dark pitcher interior, removing prey's hesitation to venture into the pitcher. The hairy lid has numerous nectar glands over its inner surface.

The lid is immobile, at least for the purpose of prey trapping, but it is often observed that the front half of the lid bends down slowly to prevent the loss of liquid inside when the air humidity decreases.

In terms of evolution, the Cephalotus pitcher is not related to pitchers of other carnivorous plants. In Cephalotus, the lid of the pitcher does not represent the leaf tip, morphologically. Rather, the petiole divides into two parts in its development, one becoming the pitcher body and the other the lid.

PREY

Ants are primary prey, as can be suspected from the pitcher lying on the ground, but some flying insects also fall victims to the nectar allure.

INFLORESCENCE

In their native Australia, Cephalotus flowers in summer (January-February). A flower stalk appears in the rosette center in early summer that grows to an unusually tall height of 2-3 feet. This makes the flower stand out among surrounding vegetation for pollinators. More importantly, the tall scape provides for a spatial separation of pollinator-prey zones.

Many small flowers are borne at the tip of a tall stalk. Each flower is only 4 mm across and white to pale green in color. The flower has no petals and 6-7 sepals give the flower its color. One flower produces only several seeds at most. Cephalotus is a hairy plant and the seeds are also covered with fine hairs. The plant is a slow grower and it takes many years for the seedling to reach a flowering age.

Return to Introduction

There are eight species of eastern North American pitcher plants all occurring in the Atlantic coastal regions of North America. Of these, seven species are confined to the southeastern part of the United States where they typically inhabit wet, sandy areas in the pineland, sometimes localized and rather isolated, but often with two or more species sharing the same habitat. This often results in various hybridization. One species extends its distribution all the way northward deep into a large part of eastern Canada.

Pitcher plants are herbaceous (non-woody) perennials consisting of a rhizome with thick fibrous roots. The hollow trap leaves arise directly from the rhizome above the ground. The pitcher leaves form a rosette and are erect or nearly so in most species but are decumbent in some. The lid develops at the upper end of the pitcher. The lid is typically reflected over the pitcher opening, but can develop to form a domed hood in some species. The mature pitchers range in height from 10 to 100cm, or even more at times, depending on the species and growing conditions. See Description for more.

General

The plant was discovered in 1841 by W. D. Brackenridge, assistant botanist of the U.S. Exploring Expedition, in a marsh a few miles south of Mt. Shasta in northern California. John Torrey, a distinguished botanist of the 19^th century, recognized a close relationship to the eastern pitcher plants yet a clear difference in floral characteristics, and established a new genus in the pitcher plant family, naming it Darlingtonia californica, in honor of his friend and botanist, William Darlington.* The genus Darlingtonia is monotypic, i.e. only one species in the genus. The pitcher plant family Sarraceniaceae contains two other genera, Sarracenia (Eastern pitcher plants) and Heliamphora (South American pitcher plants).

Heliamphora was discovered by Sir R. Schomburgk on Roraima in 1838. The genus name translates to the "marsh pitcher"...

Most species have a short stem from which erect leaves arise, but some have a stem reaching 1 m or more.....

GENERAL

Roridula, in the monotypic family Roridulaceae, contains two species from the southwestern corner of South Africa, R. dentata and R. gorgonias, both occurring in the Cape Floristic Region near Cape Town. The region is characterized by nutrition-poor soils in the climate of warm, dry summers and cool, wet winters. The plants are perennial having woody stems. The larger of the two, R. dentata, often reaches more than 1 m in height. Their branching stems have many slender leaves covered with sticky hairs.

The plants use a flypaper trap to catch insects on their leaves, which are covered with stalked glands that secrete sticky glue. The plants look similar to some of the sundew species. This similarity, however, is more apparent than real. Unlike the mucilaginous secretions in Drosera, the glands on the Roridula leaf produce powerful resin. Water-based mucilage can be readily absorbed through the leaf surface, which is not the case for resinous glue. For this reason and the fact that the plants do not produce digestive enzymes, Lloyd and others had rejected the notion that Roridula plants were true carnivores. Recent studies have shown, however, that Roridula maintains a mutualistic relationship with assassin bugs (Rameridea) living on the plants. In fact, each species of Roridula has its own kind of assassin bug (Opel, 2005). The assassin bugs can freely move around on the sticky leaves without being caught. These carnivorous bugs live on the prey caught on the Roridula leaves. Indeed, these bugs are said to be found nowhere other than on Roridula plants. The excretion of the bugs deposited on the leaf is now absorbed by the glands on the leaf. The bugs serve as a surrogate to digest the prey for the plants. This arrangement, in principle, is no different from the case where the exogenous microorganisms like bacteria are used to perform the digestion of prey in many carnivorous plants some time during their digestion cycle.

The leaves have two kinds of glands. The stalked glands that secrete resinous glue are far simpler in structure compared with those in Drosera. The stalk is multi-cellular, but no vascular system is seen. The stalk shows no movement and the secretions appears to occur only once. The leaf surface contains simple sessile glands also, which are speculated to be responsible for absorption.

General

There are about 80 species of butterworts worldwide. Many can be found in Mexico and in Europe. They grow on wet, dripping, moss-covered rocks in the mountains, on moist, grass-covered sandy ditches in savannas, and in other similar conditions, sometimes in company of other carnivorous plants. Of six species found in the southeastern United States, five are indigenous to the region. Three other species grow in northern U.S. and Alaska.

General

In the ponds and ditches, one may find floating, rootless plants with hundreds of tiny, balloon-like sacs attached to their green branching stems. They are bladderworts, yet another kind of carnivorous plants. These sacs in the water are sophisticated miniature traps designed to provide animal meals for these rootless floaters.

There are about 210 species of bladderworts worldwide, occurring practically every part of the globe. Some are terrestrial species found in moist-to-wet, often acid soils, and in sphagnum moss, while others are aquatic, preferring to be floating freely in quiet waters in ponds and ditches. Many terrestrial species in the tropics are epiphytic.

Some species exhibit intermediate life style, capable of adapting to either terrestrial or semi-aquatic habitats depending on the amount of rainfall of the season. Of all the bladderworts in the world, terrestrial species are, by far, the majority. Twenty species are found in the U.S. See Description for more.

GENERAL

The genus Byblis belongs to the monotypic family Byblidaceae. Their slender leaves covered in glistening dews, the rainbow plants are so named because of the rainbow effect of their mucilage secretions. With recent additions to the genus, there are now five species all occurring in Australia. Molecular analysis shows that Byblis is related to both Pinguicula and Ibicella.

The plants have light green thread-like leaves. The leaves radiate in all directions from the stem. The whole plant, including stems and flower stalks, is covered with fine, sticky hairs. The clear mucilage envelopes the tip of each hair to entrap small insect prey. In Byblis, the stalked mucilage glands remain green.

The climate of the habitat is characterized by wet winters and long, hot, dry summers. The plants' shoots die back during the dry period, being dormant in the form of rootstock, only to emerge again at the onset of winter rains.

Rainbow is a well-understood physical phenomenon created by optical properties of a sphere, as in air-borne vapors in the misty sky faraway. Thanks to the erect posture of the plants, the field densely populated with a massive number of rainbow plants, with their million dew drops, can effectively simulate a rainbow, with the refraction of sun's ray, causing differing wavelengths to form a spectrum of rainbow.

If you ever encounter such a situation in the field, just remember that the center of rainbow is always where your head casts its shadow - the anti-solar point.

Two type of glands are seen on the leaf surface, the stalked glands and sessile glands. The stalked glands (similar to those in Pinguicula, dissimilar to those in Drosera) have a unicellular stalk, with as many as 32 glandular cells at the tip of the stalk. The sessile glands, far more numerous than the stalked glands, have 8 glandular cells. The sessile glands secrete mucilage only when stimulated, and occur also on the adaxial surface where no stalked glands are seen. The main purpose of sessile glands appears absorption.

The plant was initially described under Martynia lutea. Suggested as a possible carnivore by Beal in 1875, Mameli further established its carnivorous nature in 1916 (Juniper, et al). Lloyd somehow missed the papers, and did not include Ibicella in his book, The Carnivorous Plants (1942).

Of fifteen of so species of the family Martyniaceae, three species are suspected to be carnivorous: Ibicella lutea, Proboscidea parviflora and Proboscidea lousianica.

The plants grow natively in the arid soil in South America, but are now naturalized in southern California deserts. The upper surface of the leaves as well as the stems are covered with short hairs tipped with a sticky mucilage. These short hairs are only capable of trapping gnats and small dipterans, but often rather effectively. Studies have failed to detect any digestive enzyme production. The trapped prey is decomposed by the aids of external bacteria before the leaf can absorb its nutrients.