Philodendron pseudauriculatum Croat

 

Philodendron pseudauriculatum Croat

Note:  Despite the fact it may appear this name should begin with "pseudo" the scientific spelling on this page is correct.
P. pseudoauriculatum is an incorrect spelling

Philodendron pseudauriculatum (suud-AH-ric-u-lat-um) was published to science in the Annals of the Missouri Botanical Garden Volume 84, Number 3 in 1997.  The species was described by aroid botanist Dr. Thomas B. Croat Ph.D., P.A. Schulze Curator of Botany of the Missouri Botanical Garden in St. Louis.  Dr. Croat is one of the world's leading aroid scientists.  The description can be found on page 498 of that journal and all the scientific material in this article was taken from that publication. 

Although it may appear to some the word "pseudo" should have been used, in Latin "pseud" is used as a combining form as when combining the words  "pseudo" (meaning not authentic) and "auriculatum" (to possess ear lobes).

Philodendron pseudauriculatum occurs only in Panama as well as in the in the northwestern portion of the adjacent country of Colombia down to Antioquia.  Although the specimens found in the Chocó differ somewhat it is also possible this species may occur in Chocó Department (similar to a state) in western Colombia. 

The species is found at elevations ranging from 20 to 1400 meters (65 to 4600 feet) above sea level and occurs in pre-mountainous wet forests as well as as wet rain forest zones.  The majority of collections of Philodendron pseudauriculatum have been made near La Mesa (Coclé), Cerro Campana in south central Panama where it may be observed along the road leading from El Llano to Cartí.  It is also known from a lone collection in Bocas del Toro on the mid-central Atlantic coast as well as a collection in the Serranía de Cañasas near the Pacific Ocean. 

The genus Philodendron is divided into three subgenera including subgenus Philodendron, subgenus Meconostigma and subgenus Pteromischum.  These subgenera are further divided into sections as well as subsections and series based on the specific characteristics of a species.  Philodendron pseudauriculatum is a member of Philodendron subgenus Philodendron, section Calostigma, subsection Glossophyllum and is placed in series Glossophyllum. 

The type specimen was collected in Panama along the El Llano to Cartí road four miles from the Inter-American Highway near El Llano at an elevation of 300 meters (almost 1000 feet) on March 27, 1976.  A type specimen is a carefully dried specimen stored in the herbarium of one or more recognized botanical gardens and is used to compare all further collections as to species validity.  The original type was stored as Croat specimen 33730.  Dried specimens are extremely valuable to a botanical scientist since the specific characteristics (including the dried color) of a specimen become much more obvious once dried.

Philodendron pseudauriculatum is somewhat similar in shape (thus its name) to Philodendron auriculatum which is primarily from Costa Rica but has also been observed in Panama, Colombia and Brazil.  Philodendron auriculatum can be distinguished since it possesses leaf blades that dry to a pale yellow green color and has more narrow posterior lobes toward the base.  The term auriculate indicates the plant has "ears" or earlobe-shaped extensions at the base which is the top of the blade (see photos below).  Philodendron pseudauriculatum is even more easily confused with Philodendron ligulatum as well as several natural variations of that species since they have similarly shaped blades.  Based on Dr. Croat's work Philodendron pseudauriculatum also bears a similarity to Philodendron dolichophyllum which is another Panamanian species placed in Philodendron section Glossophyllum.  Both species possess petioles and blades of similar length but Philodendron pseudauriculatum differs by having much shorter leaves as well as sunken primary lateral leaf veins (see explanation below).  There is also a similarity to Philodendron bakeri but P. bakeri has much fewer primary lateral leaf veins (3 to 4) and the annulus (colored ring) at the top of the petiole is purple instead of green.

A climbing vine, Philodendron pseudauriculatum grows as a hemiepiphytic species and climbs appressed to its host tree.  A hemiepiphyte (hem-a-EPA-fit) is a plant that may begin life as a seed which falls to the ground or as a seed which was placed on the branch of a tree in the droppings of a bird or other rain forest animal that subsequently sends its roots to the soil.  An appressed vine is one that grows pressed quite close to its host.

When attempting to identify any aroid species the specific characteristics of the specimen being researched are important.  One goal of this article is to attempt to explain and illustrate those distinguishing characteristics in a way any collector can use to verify whether or not a plant is or is not the species in question.  Although scientific terminology is used in this article we attempt to explain each term so the reader may find this article both explanative and educational.  Please do not abandon reading this piece simply because scientific language is used.

Since all Philodendron species (and many other plants) are variable some characteristics including the shape of the blade, coloration of the inflorescence and other features may vary from specimen to specimen.  You should not assume every single specimen of any species will look exactly alike.  For an explanation of natural variability in aroids please consult this link:  Natural variation in aroids

 

Blades

The leaf blades of Philodendron pseudauriculatum stand erect and grow in a roughly rosulate form (photo above, right).  Rosulate indicates the leaves spread in a relatively uniform pattern around the central axis as well as grow in a formation similar to the petals of a rose.  The leaf blades of Philodendron pseudauriculatum grow with oblong-elliptic to oblanceolate-elliptic shape which describes a blade that is both oblong while elliptical (wider at the center) and/or shaped similarly to the weapon known as a lance (lanceolate).  The blades are considered subcoriaceous to coriaceous.  Subcoriaceous indicates the blades are less than leathery to the touch while coriaceous indicates they possess the feel of leather.   The leaf blades are slightly to markedly two colored (bicolorous) and are semi-glossy on the adaxial (upper) blade surface.  The blades are also acuminate.  The botanical term acuminate indicates the blades taper to a point.   Since this species is variable the blades may also be sub-cordate (heart shaped) which would indicate they may grow with an exaggerated as well as elongated heart shape.  The blades may be between 27 to 80 cm (10.5 to almost 32 inches) in length.  Although not always present, when it is observed the sinus may be as deep as 2.5 cm (almost 1 inch) in depth.  A sinus is the opening between the lobes near the base (top) of the leaf blade. 

The veins on any leaf are divided into classifications which include the basal ribs, midrib, primary lateral veins, interprimary veins and tertiary or minor veins  The midrib at the center of any leaf of Philodendron pseudauriculatum is flattened at the base but slightly sulcate midway down the rib.  The term sulcate may indicate either a canal running along the rib or small parallel groves running along its axis.  The midrib is also widely convex (raised) at the apex (top) as well as concolorous (single colored) on the  upper blade surface.  The midrib is paler in color on the underside (abaxial surface) of the leaf blade.  The lower surface of the midrib (abaxial) exhibits short green lines and is lineate (lined). 

The basal leaf veins at the extreme top of a leaf's lobe grow from the midrib uninterrupted (free) to the base  There are 8 to 14 primary lateral veins on each side of the midrib (see photos above and right) which depart the midrib at an angle of 65 to 75 degrees but the angle narrows nearer the apex (top) of the blade.  The primary veins run almost straight to the margins (edges) of the leaves and are sunken on the upper surface while raised on the underside of the blade.  The primaries are somewhat paler in color on the abaxial surface of a blade.  The interprimary veins are flat as well as darker on the underside and arise from both the midrib and primary lateral veins.  The tertiary or minor veins are only slightly distinct on the underside. 

 

Petioles

Philodendron species are members of the larger plant family known as Araceae and are commonly called aroids.  Aroids are characterized by the growth an inflorescence known to science as a spathe and spadix which contain the reproductive organs of the plant.  The spathe is simply a modified leaf which appears in the shape of a hood while the spadix is located at the center of the inflorescence.  The spadix is a spike on a thickened fleshy axis which can produce tiny flowers.  Despite being called a "flower" on far too many websites the spathe is not a flower. Flowers contain near microscopic sexual parts including the anthers, stamens, and stigmas when the plant is in the reproductive process.  A spathe contains none of these sexual characteristics but all can be observed with a good magnifying glass on the true flowers along the spadix.  When an aroid is referred to as "flowering" the reference is to the very small flowers which are produced along the spadix and has nothing to do with the spathe.  The only connection is both are produced during the plants sexual reproduction known as anthesis. 

When ready to reproduce the spadix of a Philodendron produces male, female and sterile flowers which are cleverly divided by nature into separate zones in order to prevent self pollination.  The female flowers as well as the sterile male flowers are hidden inside a region at the bottom of the spathe known as the "floral chamber" while the fertile male flowers are exposed on the visible portion of the spadix.  The purpose of the sterile male flowers is to produce a perfume-like substance known as a pheromone which attracts pollinating insects.  The sterile flowers also serve as a source of food in the form of protein to those pollinators. 

Philodendron species produce the female flowers on the first evening of anthesis and are no longer receptive by the time the male flowers begin to produce pollen on the second (possibly the third) evening.  If the female flowers are pollinated with pollen of the same species which is already at male anthesis carried by an appropriate beetle in the genus Cyclocephala from another specimen they will produce berries containing seeds.   The berries (fruits) are white turning to orange when mature and the berries normally contain 5 seeds per berry.

Once mature Philodendron pseudauriculatum produces two to three inflorescences per axil.  The peduncles which supports the inflorescences measure between 5.5 and 21 cm but may grow up to 25 cm (2.1 to 9.85 inches) in length and are the internodes between the spathe and the last foliage leaf.  The peduncle is medium to pale green and is finely striated.  The botanical term striate indicates fine parallel lines.  The spathes are green and somewhat pinkish and measure between 12 and 23 cm (4.7 to 9 inches) in length and are constricted midway up the spathe tube.  The spathe coloration has white to pinkish on the margins (edges).  The spathe blade (the upper margin of the tube) is creamy white to yellowish green with a faint green tinge at the  center on the backside while yellow orange striated on the  outside and pale green to whitish on the inside.  The spathe tube is oblong to ellipsoid and is sometimes sometimes slightly tinged purplish along the outside margins.   Flowering in Philodendron pseudauriculatum occurs during the dry season in Central America as well as the first half of the rainy season which is January through September.  Mature fruits are only known to be observed after September.  

For more information how Philodendron and other aroids reproduce click this link  Aroid Pollination

The specimen shown in the photos on this page was acquired for the ExoticRainforest collection as an adult specimen grown from a cutting from the collection of the Missouri Botanical Garden.  The specimen was grown at MOBOT from specimen number 33526.  The parent plant was collected by Dr. Croat on March 21, 1976 near Nuevo Tonosi 32. KM (2 miles) from Portobello on the road to Nombre de Dios, Panama at an elevation of 100 meters (330 feet) above sea level,  The exact collection coordinates were recorded as  09°33'00"N 079°37'30"W