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Philodendron

[fil-uh-den-druhn]

Philodendron is a large genus of flowering plants from the arum family (Araceae), consisting of close to 900 or more species according to TROPICOS (a service of the Missouri Botanical Garden). Other sources quote different numbers of species. According to S.J. Mayo there are about 400 formally recognized species whereas according to Croat there are about 700. Whichever the exact number of species, the genus is the second largest member of the arum family. Taxonomically the genus Philodendron is still poorly known with many undescribed species. Many are grown as ornamental and indoor plants. The name derives from the Greek philo or "love" and dendron or "tree".

Distribution

Philodendron species can be found in many diverse habitats in the tropical Americas and the West Indies. Most occur in humid tropical forests, but can also be found in swamps, on river banks, roadsides and rock outcrops. They are also found throughout a diverse range of elevations from sea level to over 2000 meters. Species of this genus are often found clambering over other plants, or climbing the trunks of other trees with the aid of aerial roots. Philodendron usually distinguish themselves in their environment due to their large numbers compared to other plants making them a highly noticeable component of the ecosystems they're found in. Additionally, they are found in great numbers on the sides of road clearings.

Philodendrons can also be found in Australia, some Pacific islands, and Asia although they aren't indigenous to these regions. Rather they were introduced or accidentally escaped.

Description

Growth Habit

Compared to other genera of the family Araceae, Philodendron have an extremely diverse array of methods by which they grow. The habits of growth can be epiphytic, hemiepiphytic, or terrestrial although very few Philodendrons grow terrestrially. Others can show a combination of these growth habits depending on the environment the plant is in. Hemiepiphytic Philodendron can be classified into two types, primary and secondary hemiepiphytes. The primary hemiepiphytic Philodendron start their life high up in the canopy where the seed initially sprouts. The plant then grows as an epiphyte gaining size and then once it has reached a sufficient size and age, it will begin producing aerial roots that grow towards the forest floor. Once the roots have reached the forest floor, nutrients can be obtained. In this manner the plants strategy is to obtain light early in its life at the expense of nutrients. Some primary epiphytic species have a symbiotic relationship with ants. In these species the ant's nest is grown amongst the roots of the Philodendron and help keep the nest together. Additionally, Philodendron have extra floral nectaries that secretes nectar that attracts the ants. The Philodendron in tern obtains nutrients from the surrounding ant nest and the aggressive nature of the ants serves to protect it against other insects who would choose to eat it. Secondary hemiepiphytes start their life off on the ground or on part of a tree trunk very close to the ground where the seed sprouts. For these Philodendron they have their roots in the ground early on in their lives. They then begin climbing up a tree and eventually may become completely epithytic by doing away with their subterranean roots. Secondary hemiepiphytes don't always start off their lives close to a tree. For these Philodendron what happens is that the plant will grow with long internodes along the ground until a tree is found. They find a suitable tree by means of growing towards darker areas since trees produce a dark shadow. This trait is called scototropism. After a tree has been found the scototropic behavior stops and the Philodendron switches to a heliotropic growth habit and shortens the internodes and makes them thicker. Usually however Philodendron germinate on trees.

Leaves

The leaves are usually large and imposing, often lobed or deeply cut, and may be more or less pinnate. They can also be oval, spear-shaped, and have many other possible leaf variations. The leaves are borne alternately on the stem. An interesting quality of Philodendrons is that they don't have a single type of leaf on the same plant. Instead they have juvenile leaves and adult leaves both of which can be drastically different from one another. The leaves of seedling Philodendron are usually heart-shaped. Then after it has matured from the seedling stage but still early in the life of the Philodendron the leaves will have the typical juvenile leaf's shape and size. Then later in the Philodendron's life the plant will be triggered to start producing adult leaves. This mechanism is called morphogenesis. Most Philodendron go through the process of morphogenesis gradually and there isn't an immediate distinct difference between the juvenile and adult leaves. The adult leaves are typically much bigger than the juvenile leaves, but the shape can be significantly different. In fact there has been considerable taxonomy difficulties in the past due to the differences between the juvenile and adult leaves where the juvenile type plant would mistakenly be classified as a different species than the adult type plant. The mechanism that triggers the plant to undergo transformation to its adult type leaves can vary considerably as well. One possible thing that could trigger the plant to undergo this transformation is the height of the plant. For these primary hemiepiphytes they will start off on the bottom of the dark forest floor and climb their way up a tree displaying their juvenile type leaves along the way. Once they reach a sufficient height they will begin developing their adult type leaves. For these types of Philodendron the smaller juvenile leaves are used for the darker forest floor where light is in scarce supply, but once they reach a sufficient height in the canopy the light is bright enough that the bigger adult leaves can serve a useful purpose. Another trigger that leads some Philodendron to morph into their adult form occur in secondary hemiepiphytes. These Philodendron will typically send their aerial roots downward. Once their roots have reached the ground below the plant will begin taking up nutrients from the soil that it had been deprived of all its life. As a result the Philodendron will quickly morph into its adult leaves and the plant will get enormous quickly. Another interesting quality of Philodendron leaves are that often they are quite different in shape and size even when comparing two Philodendron of the same species. As a result of all these different possible leaf shapes it often is difficult to differentiate natural variations from morphogenesis.

Cataphylls

Philodendrons also produce cataphylls, which are modified leaves that surround the newly forming leaves. The cataphylls serve the purpose of protecting the developing leaves. The cataphylls are usually green, leaf-like, and rigid while they are protecting the leaf. In some species they can even be rather succulent. Once the leaf has been fully formed, the cataphyll usually remains attached where the stem and base of the leaf meet. In Philodendron, cataphylls typically fall into two categories: deciduous and persistent types. For deciduous cataphylls the cataphyll will curl away from the leaf once it has formed and begin to dry out, eventually turning brown. While it's drying out it remains attached to the stem for a period of time before finally falling off the plant. In its place the cataphyll leaves a scar on the stem where it was attached. Deciduous cataphylls are typically found on vining Philodendron, whereas persistent cataphylls are typically found on epiphytic Philodendron or appressed climbers. For these types the cataphylls are prevented from falling off in a timely manner due to the short internodes of the plant. The cataphylls will remain attached, dry out, and eventually become broken down by the weather and decomposition. Eventually they will become nothing more than fibers attached at the node. In some Philodendron the cataphylls build up over time and eventually form a wet mass at the nodes. This may serve the purpose of keeping emerging roots moist and of providing some form of lubrication to new leaves.

Roots

Philodendrons have both aerial and subterranean roots. The aerial roots are found in many shapes and sizes and originate from most of the plant's nodes or occasionally from an internode. The size and number of aerial roots per node depends on the presence of a suitable substrate for the roots to attach themselves. Aerial roots serve two primary purposes. They allow the Philodendron to attach itself to a tree or other plant and they allow it to collect water and nutrients. As such the roots are divided morphologically into these two categories. Aerial roots that are used for attaching to trees tend to be shorter, more numerous, and sometimes have a layer of root hairs attached. Whereas aerial roots that serve the purpose of collecting water and nutrients tend to be thicker and longer. These feeder roots tend to attach flush with the substrate that the Philodendron is attached to and make their way directly downwards in search of soil. In general, feeder roots tend to show both positive hydrotropic and negative heliotropic behavior. Characteristic to the roots in Philodendrons is the presence of sclerotic hypodermis, which are cylindrical tubes inside the epidermis that can be up to one to five cells long. The cells that line the sclerotic hypodermis are elongated and tend to be hardened. Additionally, underneath the epidermis is found a unique layer of cells that have a pattern of long cells followed by short cells.

Extra Floral Nectaries

In order to attract ants for the purpose of protection Philodendrons utilize extra floral nectaries which are nectar producing glands found outside of the flowers. They can be found on a variety of locations on the plant which include the stalks, sheaths, lower surface of the leaves, and spathes. The nectaries produce a sweet sticky substance that the ants like to eat and which provides an incentive for them to build their nests amongst the roots of the given Philodendron. In some cases the amount of nectar produced can get quite extensive resulting in the given surface becoming entirely covered with nectar.

Toxicity

Philodendrons can contain as much as 0.7% of oxalates in the form of calcium oxalate crystals. The risk of death is quite low if ingested by an average adult although its generally considered unhealthy to consume parts of Philodendrons. In general the calcium oxalate crystals have a very mild effect on humans. Large quantities generally have to be consumed for symptoms to appear. If consumed the possible symptoms include increased salivation, a sensation of burning of the mouth, swelling of the tongue, stomatitis, dysphagia, an inability to speak, and edema. There has been one recorded case of an infant eating small quantities of Philodendron resulting in hospitalization and death, but its likely extremely rare. Cases of mild dermatitis due to contact of the leaves of some Philodendron with the skin in some individuals have also been reported. The symptoms included vesiculation and erythema. The chemical, alkyl resorcinol, is believed to be responsible for the dermatitis in some people. Contact of the oils or fluids from Philodendron with eyes have also been known to sometimes result in conjunctivitis.

As to the toxicity of Philodendrons in cats the evidence is conflicting. In one study conducted by M. J. Greer, 72 cases of cat poisonings were examined, of which 37 resulted in the death of the cat. The symptoms of the poisoned cats included excitability, spasms, seizures, renal failure, and encephalitis. However, in a study conducted by Sellers et al., three cats were tube fed Philodendron cordatum and showed no signs of the plant being acutely toxic. In this study two adult cats and one kitten were fed a puréed leaf and water mixture, observed afterward, then euthanized, and finally a necropsy was performed. A dosage of 2.8, 5.6, and 9.1 g/kg were used and the highest dosage administered was considered to be way more than any house cat could consume. The results were that all three cats showed none of the symptoms found in past epidemiological studies and appeared normal. Additionally, the necropsy showed nothing that would suggest toxicity. It has been suggested that the past epidemiological studies may be wrong since its possible that sick cats may be inclined to eat plants when they get sick. If this were the case then such studies would be incorrectly attributing the sickness of the cats with Philodendrons. It has also been suggested that the forced feeding study may have not observed Philodendron's toxicity because of the tube feeding bypassing the mouth and hence minimizing such irritation.

Some Philodendrons are however known to be toxic to mice and rats. In a study conducted by Der Marderosian et al., 100mg of Philodendron cordatum leaves suspended in distilled water were fed to six mice. The results were that three of the mice died. The same experiment was done with 100mg of Philodendron cordatum stems on three mice and none of them died. Leaves and flowers of Philodendron sagittifolium was also orally administered in 100mg doses to the mice. Three mice were used for each of the leaves and flowers. The results were that none of the mice died. A similar experiment was done on rats with the leaves and stems of Philodendron cordatum, but instead of oral administration of the dose it was injected intraperitoneally using 3g of plant extract from either the leaves or stems. Six rats were injected with the leaf extract and five of them died. Eight rats were injected with the stem extract and two of them died.

Reproduction

Sexual

When Philodendrons are ready to reproduce they will produce an inflorescence which consists of a leaf-like hood called a spathe within which is enclosed a tube-like structure called a spadix. Depending on the species of Philodendron a single inflorescence can be produced or a cluster of up to 11 inflorescences can be produced at a single time on short peduncles. The spathe tends to be waxy and its usually bicolored. In some Philodendron the base of the spathe is of a contrasting color to the upper part and in others the inner and outer surface of the spathe differ in coloration. The paler color tends to be either white or green whereas the darker color is usually red or crimson. Pelargonidin is the predominant pigment causing the red coloration in the spathes. The upper portion of the spathe is called the limb or blade, while the lower portion of the spathe is called the convolute tube or chamber due to its tubular structure at the base. As for the spadix, its more often than not white and shorter than the spathe. On the spadix is both fertile female, fertile male, and sterile male flowers. The fertile male and female flowers are separated on the spadix by a region known as the sterile zone which is composed of the sterile male flowers. The sterile zone is also commonly called the staminodial region. This barrier of sterile male flowers ensures that fertile male flowers don't fertilize the female flowers. The arrangement tends to be setup vertically with fertile male flowers at the top of the spadix followed by sterile male flowers, and finally fertile female flowers very close to the bottom in the region known as the spathe tube or chamber. In some Philodendron there is an additional region of sterile male flowers at the top tip of the spadix as well. Additionally, the fertile female flowers are often not receptive to fertilization when the fertile males are producing pollen which again prevents self-pollination. The pollen itself is thread-like and appears to project out from the region where the fertile male flowers are located.

Sexual reproduction is achieved by means of beetles, where many Philodendron species require the presence of a specific beetle species to achieve pollination. The reverse is not always the case as many beetle species will pollinate more than one Philodendron species. These same beetles could also pollinate other genera outside of Philodendron as well as outside of the family Araceae. The beetles that do the pollinating are males and members of the subfamily Rutelinae and Dynastinae, and to date the only beetles that have been seen to pollinate the inflorescence are in the genera Cyclocephala or Erioscelis. There are other smaller types of beetles in the genus Neelia that visit the inflorescences as well but they are not believed to be involved in pollinating Philodendron. In order to attract the beetles the sterile male flowers give off pheremones that attracts the male beetles usually at dusk. This process is called female anthesis and is followed by male anthesis in which the pollen is produced. Female anthesis typically lasts up to 2 days and includes the gradual opening of the spathe to allow the beetles to enter. There has been some evidence to suggest that the timing of opening of the spathe is dependent on light levels. Where cloudy darker days result in the spathe opening up earlier than on clear days. During female anthesis the spadix will project forward at roughly 45 degrees relative to the spathe. The spathe serves the purpose of providing a safe breeding area for the beetles. As such the male beetles are often followed by female beetles with the intent of mating with the male beetles within the spathe. The Philodendrons benefit from this symbiotic relationship because the male beetles will eventually leave the spathe covered in pollen and repeat the process at another Philodendron; pollinating it in the process and thus providing Philodendrons a means of sexual reproduction. The benefit of the beetles is a little less obvious. In addition to gaining a safe location to mate, the male beetles may benefit from having a central location because it allows them to broadcast to females that they are willing and able to mate. Females who see a male beetle headed for a Philodendron flower know that he does so with intention of mating and females who are sexually receptive and need to mate know that they can find males if they follow the pheromones produced by the Philodendron flowers. As a result, the male beetles benefit from this relationship with the Philodendrons because they don't have to produce pheromones to attract females since the Philodendrons do it for them. Additionally, male beetles benefit from the fact that they are ensured of mating with only sexually receptive females, something that is not neccesserily certain if the beetle is flying through the rainforest in search of females. In doing so, the Philodendron provides male beetles a means of finding female beetles that proves to be more efficient than what it could achieve on its own. Interestingly, there is some evidence to suggest that the pheromones produced by the Philodendrons are similar to those produced by female beetles when they wish to attract males to mate, although as of yet this isn't conclusive. Also, the pheromones produced has a sweet fruity smell in many species and no noticeable smell for others. In addition to the reproductive benefits provided to the male beetles the Philodendrons provide food in two forms. Pollen from the fertile male flowers are edible and are eatin by the Beatles throughout the night. Secondly, the sterile male flowers themselves are consumed by the beetles and are rich in lipids.

The male beetles will stay overnight in the spathe, eating and mating throughout the night due to the benefits provided by the spathe and spadix. Typically, 5 to 12 beetles will be within the spathe throughout the night. However, rarely cases of 200 beetles at a time have been observed and almost always the beetles are of the same species. Another interesting feature of this symbiotic relationship that is less well understood, is the series of events in which the spadix begins to heat up prior to the spathe opening up for the beetles. This process is known as thermogenesis. By the time the spathe is open and the beetles have arrived the spadix is usually quite hot; up to around 46°C in some species, but usually around 35°C. The thermogenesis coincides with the arrival of the beetles and the temperature appears to increase in their presence. An additional characteristic is that the temperature of the spadix doesn't appear to depend on the outside ambient temperature. The time dependence of the temperature can vary from species to species. In some species the temperature of the spadix will peak on the arrival of the beetles then decrease and finally increase reaching a maximum once again when the Philodendron is ready for the beetles to leave. Other species however, only show a maximum temperature on the arrival of the beetles which remains roughly constant for about a day and then steadily decreases. It has also been observed that a few species will show three peaks in temperature during the flowering. The increased temperature serves the purpose of increasing the metabolism of the beetles causing them to move about more within the spathe and increasing the likelihood that they will be sufficiently coated with pollen. A sticky resin is also produced in drops attached to the spadix which help to keep the pollen attached to the beetles. This resin producing quality is unique to Philodendron and Monstera as that other genera of Araceae don't produce it on their spadix. The resin is also found on the stems, leaves, and roots of Philodendrons. Its color can be red, orange, yellow, or colorless when it is first produced. Yet, over time it will turn brown as it is exposed to air. There is also some evidence to suggest that the thermogenesis triggers the beetles to mate. It also appears to serve the purpose of propagating the pheromones into the air. The reason for the spadix being held at 45 degrees relative to the spathe has been suggested to be for the purpose of maximizing the heats ability to waft the pheromones into the air. For a long time the means by which thermogenesis worked wasn't understood, but it is now known to occur by means of rapidly oxidizing stored carbohydtrates and lipids. The part of the spadix that heats up is the sterile zone. As the sterile zone heats up carbohydrates are burned, but once the spadix has reached its maximum temperature lipids are being oxidized. The burning of lipids is a particularly interesting feature found in Philodendrons since previously it was believed that only animals were capable of oxidizing lipids. It should be noted that the lipids aren't first converted to carbohydrates but rather are directly oxidized. This is an example of convergent evolution where two unrelated lifeforms exhibit the same trait. For Philodendrons however the oxidation of lipids is done for the purpose of generating heat whereas in animals it is often done for the purpose of generating ATP. The thermogenic reaction is triggered when concentrations of acetosalicitic acid form in the sterile zone. The acetosalicitic acid sets off the mitochondria in the cells that make up the sterile zone to switch to an electron transport chain called the cyanide resistant pathway which results in the production of heat. Philodendrons consume oxygen during thermogenesis. The rate at which oxygen is used is remarkably high being close to that of hummingbirds and sphinx moths. It has also been observed that the spadix generates infrared radiation. As the beetles home in on the inflorescence they first move in a zig-zag pattern until they get reasonably close at which time they switch to a straight line path. It has been suggested that the beetles are using scent to find the inflorescence when they are far away, but once they reach a certain distance they find it by means of the infrared radiation. This would account for the two different types of paths the beetles follow as they attempt to find a Philodendron inflorescence.

Once female anthesis is nearing its end and the female flowers have been pollinated the spathe will be fully open and male anthesis begins. In the beginning of male anthesis the fertile male flowers complete the process of producing the pollen and the female flowers become unreceptive to further pollination. Additionally, the spadix moves from its 45 degree position and presses up flush to the spathe. Towards the end of male anthesis the spathe begins to close from the bottom working its way up and forcing the beetles to move up and across the upper region of the spathe where the fertile male flowers are located. In doing so the Philodendron controls when the beetles come and when they leave and forces them to rub against the top of the spadix where the pollen is located as they exit. Thus ensuring that they are well coated with pollen. One would expect that the beetles would stay indefinitely if they could due to the very favorable conditions that the inflorescence provides for the beetles. After male anthesis the male beetles will go off and find another Philodendron that is undergoing female anthesis and as a result will pollinate the female flowers with the pollen it had collected from its previous night of mating.

Fruit

Botanically the fruit produced is a berry. The berries develops later in the season where the time of development varies from species to species. It can take from a few weeks to a year for the berries to develop although most Philodendron take a few months. The spathe will enlarge to hold the maturing berries. Once the fruit are mature the spathe will begin to open again, but this time it will break off at the base and fall to the forest floor. Additionally, the berries are edible even though they contain the calcium oxalate crystals, having a taste akin to bananas. The color of the berries can vary a bit depending on the species, but most produce a white berry with slight tones of green. Some produce orange berries and others yellow berries though. Still others will produce berries that start off white, but then change to another color with time. Philodendron that produce orange berries tend to be members of the section Calostigma. Contained within the berries are the seeds which are extremely small compared to other members of the Araceae family. The berries of Philodendron often give off odors for the purpose of attracting animals to eat and disperse them. For example, Philodendron alliodorum berries are known to emit an odor similar to that of garlic. The animals that distribute the seeds depends on the species of Philodendron, but some of the possible dispersers include bats and monkeys. There is also evidence that insects are also responsible for dispersing seeds as that beetles and wasps have been seen feeding on Philodendron berries.

Another insect that seeks out Philodendrons are chalcid wasps. They are known to lay their eggs in the ovaries of many Philodendron species. The result is what is known as a galled inflorescence.

Hybridisation

Philodendron exhibit extremely few physical reproductive barriers that prevent hybrids. Even though this is the case there are very few natural hybrids that are found in nature. It has been suggested that this may be due to the fact that Philodendrons have many geographic and time barriers that would prevent any such cross pollination. For example, its rare for more than one Philodendron species to be flowering at the same time. Its also the case that since Philodendron often are pollinated by specific species of beetles that this would prevent cross pollination. The beetles have also been observed to be selective to the height of the plant they pollinate which would serve as an additional preventitive measure that would make hybrids less likely. It has been suggested that because of these outside barriers that Philodendrons haven't had to evolve physical mechanisms that would prevent cross pollination. Due to this, one rarely can find hybrids in nature although reported cases have been observed. An interesting feature of these hybrids is that they often can show remarkable types of crosses with regards to genetic relation. Crosses between two Philodendrons in different sections can occur successfully.

Cultivation

Growing

Philodendron can be grown in outdoors in mild climates in shady spots. They thrive in moist soils with high organic matter. In milder climates the plants can be grown in pots of soil or in the case of P. oxycardium in containers of water. Indoors plants thrive at temperatures between 60-72 degrees and can survive at lower light than other house plants. However, it should be noted that although Philodendrons can survive in dark places they much prefer bright lights. Wiping the leaves off with water will remove any dust and insects. Plants in pots with good roots systems will benefit from a weak fertilizer solution every other week.

Propagation

New plants can be grown by taking stems cuttings with at least two joints. Cuttings can be then rooted in pots of sand and peat moss mixtures. These pots are placed in greenhouses with bottom heat of 70-75 degrees. During the rooting cuttings should be kept out of direct sunlight. Once rooted the plants can be transplanted to larger pots or directly outside in milder climates. A second way to propagate philodendrons is to take stems cuttings, particularly from trailing varieties, and place them in water. In four to five weeks the plant should develop roots and can be transferred to pots.

Hybridizing Philodendron is extremely easy if flowering plants are available due to the fact that they have very few barriers that prevent hybrids. However, there are some aspects to making crosses that can make Philodendron hybridization more difficult. Philodendron often flower at different times and the time that the spathe opens up varies from plant to plant. The pollen has a short shelf life along with the inflorescence itself which means that a large collection of Philodendron is necessary if hybridization is to be done successfully. The shelf life of the pollen can be extended by storing it in film canisters in a refrigerator. If this is done the pollen can last for a couple weeks. Artificial pollination is usually achieved by first mixing the pollen with water. A window is then cut into the spathe and the water-pollen mixture is rubbed on the fertile female flowers. The entire spathe is then covered in a plastic bag so that the water-pollen mixture doesn't dry out and is removed a few days later. If the inflorescence hasn't been successfully fertilized it will fall off usually within one to two weeks, but sometimes as long as a month.

Uses

The resin produced during the flowering of Monstera and Philodendron are known to be used by Trigona bees in the construction of their nests. Subsequently native Indians from South America take the resin from the bees' nests and use it to make their blowguns air and watertight.

Even though Philodendron contain calcium oxalate crystals the berries of some species are eaten by the locals. For example, in the case of Philodendron bipinnatifidum the white sweet berries are known to be used in such a fashion. Additionally, the aerial roots also used for rope in this particular species.

The leaves of Philodendron are also known to be eatin by Venezuelan Red Howler monkeys making up 3.1% of all the leaves they eat.

Also, in the making of a particular recipe for curare by the Amazonian Taiwanos, the leaves and stems of an unknown Philodendron species is used. The leaves and stems are mixed with the bark of Vochysia ferruginea and with some parts of a species in the genus Strychnos.

Yet another use of Philodendron is for the purpose of catching fish. A tribe in the Colombian Amazon are known to use Philodendron craspedodromum to add poison to the water that in turn makes it easy for them to catch fish to eat. The fish are temporarily stunned by the poison in the water and rise up to the surface where they can be easily scooped up. To add the poison to the water, the following method is used. The leaves are cut into pieces and tied together to form bundles. For a few days the bundles are allowed to ferment before they're used. The bundles are crushed and added to the water into which the poison will dissipate. Although the toxicity of Philodendron craspedodromum is not fully known, it is possible that the active ingredients in the poisoning of the fish are coumarins which are formed during the fermentation process.

Some Philodendron are also used for ceremonial purposes. Among the Kubeo tribe, native to Colombia, Philodendron insigne is used by witch doctors when they are treating ill patients. They use the juice of the spathe to stain their hands red since many such tribes view the color red as a sign of power.

Classification

History

Philodendrons are known to have been collected from the wild as early as 1644 by Georg Marcgraf, but the first semi successful scientific attempt to collect and classify the genus was done by Charles Plumier. Plumier collected approximately six species from the islands of Martinique, Hispaniola, and St. Thomas. Since then there has been many exploration attempts to collect new species by others. These include those by N.J. Jacquin who collected new species in the West Indies, Colombia, and Venezuela. At this time in history the names of the Philodendrons they were discovering were being published with the genus name Arum since most aroids were considered to belong to this same genus then. The genus Philodendron had not yet been created. Throughout the late 17th century, 18th century, and early 19th century many plants were removed from the genus Arum and placed into newly created genera in an attempt to improve upon the classification. It wasn't until Heinrich Wilhelm Schott addressed the problem of providing improved taxonomy that the genus Philodendron was created and described. This was done in 1829 and the genus was first spelled as 'Philodendrum'. Then in 1832, Schott published a system for classifying plants in the family Araceae titled Meletemata Botanica in which he provided a method of classifying Philodendrons based on flowering characteristics. In 1856, Schott published a revision of his previous work titled Synopsis aroidearum and then subsequently in 1860 published his final work Prodromus Systematis Aroidearum in which he provided even more details about the classification of Philodendron and described 135 species.

Modern Classification

Philodendron are usually extremely distinctive and not usually confused with other genera although there are a few exceptions. There are a few species that resemble Philodendrons in the genus Anthurium and Homalomena. The genus Philodendron is subdivided into several sections and subsections:

Section Baursia, section Philopsammos, section Philodendron (subsections Achyropodium, Canniphyllium, Macrolonchium, Philodendron, Platypodium, Psoropodium and Solenosterigma), section Calostigma (subsections Bulaoana, Eucardium, Glossophyllum, Macrobelium and Oligocarpidium), section Tritomophyllum, section Schizophyllum, section Polytomium, section Macrogynium and section Camptogynium.

Typically the inflorescence is of great importance in determining the species of a given Philodendron since it tends to be less variable than the leaves of the plant. It has been suggested however that the genus Philodendron could be classified further by means of differentiating them based on the pattern of thermogenesis observed although this isn't currently in use.

Selected Species

Notes

References

  • Kramer, Jack (1974). Philodendrons. Scribner. ISBN 0684136988.
  • Mayo, S. J. (1990).History and Infrageneric Nomenclature of Philodendron (Araceae). Kew Bulletin. Vol. 45, No. 1, pp. 37-71
  • Croat, Thomas B. (1997).A Revision of Philodendron Subgenus Philodendron (Aracea) of Central America. Annals of the Missouri Botanical Garden. Vol. 84, No. 3, pp. 311-704
  • Schott, Heinrich Wilhelm (1832). Meletemata Botanica.
  • Schott, Heinrich Wilhelm (1856). Synopsis aroidearum.
  • Schott, Heinrich Wilhelm (1860). Prodromus Systematis Aroidearum.
  • Bown, Deni (2000). Aroids: Plants of the Arum Family [ILLUSTRATED]. Timber Press. ISBN 0881924857
  • Gibernau, Marc and Barabé, Denis (2000). Thermogenesis in three Philodendron species (Araceae) of French Guiana. Can. J. Bot. 78(5): pp. 685–689.
  • Greer, M. J. (1961). Plant Poisonings in Cats. Mod. Vet. Pract., 42, 62.
  • Pierce, J. H. (1970). Encephalitis Signs from Philodendron Leaf. Mod. Vet. Pract., 51, 42.
  • Spoerke, David G. and Smolinske, Susan C. (1990). Toxicity of Houseplants. CRC. ISBN 0849366550
  • Richard-Hansen, Cécile and Bello, Natalia and Christophe Vié, J. (1998). Tool use by a red howler monkey (Alouatta seniculus) towards a two-toed sloth (Choloepus didactylus). Primates. Vol. 39, No. 4, pp. 545-548
  • Dart, Richard C. (2003). Medical Toxicology. Lippincott Williams & Wilkins. 3rd Edition. ISBN 0781728452.
  • Sellers, Sarah J. and King, Maralee and Aronson, Carl E. and Der Marderosian, Ara (1978). Toxocologic Assessment of Philodendron Oxycardium Schott (Araceae) in Domestic Cats. Veterinary and Human Toxicology. Vol. 20, pp.92-96, ISSN 0145-6296
  • Der Marderosian, Ara and Giller, F. and Roia, F. (1976). Phytochemical and Toxicological Screening of Household Ornamental Plants Potentially Toxic to Humans. J. Toxicol. Environ. Health. 1: 939-953.

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