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 New: Understanding, pronouncing and using Botanical terminology, a Glossary

Anthurium sagittatum (Sims) G. Don

Anthurium sagittatum (Sims) G. Don

Synonyms: Anthurium rubrinervium, Anthurium aeranthe, Anthurium alienatum,
Anthurium amazonicum, Anthurium cordatosagittatum, Anthurium humboldtianum subsp viridispadix,
Anthurium humboldtianum, Anthurium polyrrhizon, Anthurium sororium, Anthurium terrestre,
Pothos rubrinervius, Pothos sagittatus, Pothos suaveolens

The scientific information on this species was primarily extracted from the published field notes of aroid botanist
Dr. Thomas B. Croat Ph.D., P.A. Schulze Curator of Botany at the Missouri Botanical Garden in St. Louis. 
Additional material was extracted from the paper A Comparative Analysis of the Diversity, Distribution,
and Biogeography of Araceae in Southeastern Peru by Jorge Linga Chavez

Anthurium sagittatum is currently listed on the RED LIST of Endangered Species.

Published to science in 1839 by Scottish botanist George Don (1798 to 1856) in Hortus Britannicus #633, Anthurium sagittatum is placed in Anthurium section Cardiolonchium.  Section Cardiolonchium is characterized by a velutinous (velvety) sheen to the leaf blades.  The scientific term velutinous indicates the leaf surface is covered with a short fine and densely silky pubescence (hair) which causes the blade to appear to be velvety.  However, due to natural variation this characteristic is not always apparent in Anthurium sagittatum.  Botanically the species is considered sub-velvety and the species is often known to collectors as Anthurium rubrinervium (correctly a synonym).

Anthurium sagittatum is found largely in most of Colombia and Ecuador but also grows in the rain forests of Peru ranging from the Amazonas region to Loreto and Madre de Dios as well as in western and northern Brazil, Suriname, Guiana, French Guiana and almost certainly Venezuela.  Anthurium sagittatum has been found in nature at elevations ranging from 110 to as high as 3100 meters (330 to over 10,000 feet) above sea level but is observed more frequently at lower elevations ranging from 100 to 1500 meters (325 to 5,000 feet).  This Anthurium species is not known to grow epiphytically on the branches of trees but instead often grows in groups as a terrestrial species in both primary and virgin rain forests. 

Anthurium sagittatum is frequently found along trails, roads, rocky cliff banks and especially along the banks of streams and rivers.  The species appears to prefer somewhat shadowy wet places in subtropical forests and is sometimes found in depressions and swampy areas.  In Ecuador Anthurium sagittatum is reported to be commonly observed in three fourths to full shade but never in full sun.   

The name "sagittatum" originates from the botanical term sagittate which indicates a leaf that is "arrow shaped".  It is possible the species grows as a hemiepiphyte (hem-a-EPA-fit) (a species that begins life in the soil and then climbs a tree) but scientific documentation cannot be located by this author to support that possibility.  The photo to the left of Anthurium sagittatum by Elizabeth Campbell was taken near Mera, Ecuador traveling towards Llanganates Bajo in Pastaza province. The specimen is approximately 1100 meters (3,600 feet) above sea level and is fully terrestrial growing beside a gravel road in a drainage ditch of standing water. 

Aroid including Anthurium species are known to be extremely variable and not every specimen of Anthurium sagittatum will always appear exactly the same.  Variations may be found in the general shape and texture of the leaves as well as other characteristics of the plant including the coloration of the venation.  A link to an explanation of the natural variations in aroids can be found at the bottom of this article. 

Since early botanists did not have access to the scientific records and computers we have available today they sometimes granted multiple new names to the same species.  All the names listed as synonyms at the top of this page have been published as a unique scientific species but all have now been sunk into synonymy under the originally published name Anthurium sagittatum.  A synonym is simply the same species published with a new name after the original scientific name was published.  In botany the first published name becomes the accepted name and all other published names for that same plant become synonyms.  Science does not simply change names as is sometimes believed by plant collectors but instead relies on the rules of botany to grant the first properly published name to be the accepted scientific name. 

Based on the Linnean rules of nomenclature established by Swedish physician, zoologist and botanist Carl Linnaeus (1707–1778) the scheme of binomial nomenclature (two names composed of the correct genus followed by a species name) has a precise set of rules that must be followed in order to determine the proper name for any species.  As can be observed, some of the names originally used were published with the wrong genus.  The system Linnaeus devised defines the kingdom, phylum, class, genus, and species of any living organism.   One of the most basic rules of taxonomy is the earliest published scientific name correct to genus becomes the accepted name.  In this case the accepted species name is Anthurium sagittatum which was published in 1839.

My friend naturalist Joep Moonen (pronounced Yupe) who lives and works in French Guiana in the northeastern corner of South America offered this information based on his field studies of the growth of Anthurium sagittatum.  Joep has known the plant as Anthurium rubrinervium,  "It is the most common of the two terrestrial Anthurium species of French Guiana, the other being Anthurium thrinax.  Your Anthurium is not common and grows in groups in very humid circumstances preferably on rocks near criques in the shade.   In the Kaw Mountains in northeast French Guiana it grows on hill slopes in primary forest.  In French Guiana it is extremely humid with an annual rainfall in the Kaw Mountains of about 20 feet (6 meters)!"  Joep guides botanists, taxonomists, zoologists and visitors into the rain forests of French Guiana to study the natural flora and fauna.  He has personally found a number of plants not previously known to science and has several aroid species named in his honor including both Anthurium moonenii and Philodendron moonenii.

When attempting to identify any aroid species the specific characteristics of the species being researched are important.  This article attempts to explain and illustrate these characteristics in a way any collector can use to verify whether or not a plant is or is not a specific species. 

The leaf blades of Anthurium sagittatum are dark green and semi-glossy to weakly glossy on the upper (adaxial) surface but substantially paler and matte on the underside (abaxial surface).  The leaves stand erect.  The upper surface may be a mixture of velvety and matte (sub-velvety) and are subcoriaceous as well as somewhat papyraceous (papery).  Subcoriaceous indicates the blades are just less than leathery to the touch while coriaceous indicates the leaves are thick. 

The veins on a leaf are divided into classifications known as the basal ribs, midrib, primary lateral veins, interprimary veins and tertiary (or minor) veins (see both photos above right and to the left above and below),  In the case of Anthurium sagittatum the midrib, which runs down the center of the leaf blade, is narrowly raised and roughly concolorous (single colored) on the adaxial (upper) surface.  As the midrib approaches the lower blade tip the leaf rounds to a slender point known as being acute.  The primary lateral leaf veins are slightly sunken (almost appearing to be somewhat quilted).   Although sunken into the blade's upper surface the primary veins themselves are narrowly raised.  The veins are acutely raised on the abaxial surface (underside).  Both the midrib and primary veins may also be reddish in color on the underside of the leaf.   This reddish venation is where the synonym Anthurium rubrinervium (red nerve) received its name.  The tertiary (minor) veins are partially raised on the underside of the leaf and are only slightly conspicuous but are often closer to obscure.  

All Anthurium species possess a collective vein which runs near the edge of the blade.  The collective vein is a specialized vein to which other veins connect.  In the case of Anthurium sagittatum the vein runs around the entire circumference of the species' blade.  In some Anthurium species the collective vein may run only partially around the blade's circumference. 

The collective vein along with the geniculum (see below) are primary characteristics used to determine if a specimen is or is not an Anthurium.  Genera such as Philodendron do not possess either a collective vein nor a geniculum while other aroid genera may collect one or the other.

The stem is the part of the plant that forms buds, petioles (thus leaves), roots, and the peduncles that support an inflorescence (thus flowers).  The stem (photo, right) is the main axis of the plant and is the plant's base which provides support.  Although the majority of the stem grows above ground portions may also exist beneath the surface.  The purpose of the stem is to collect and store water and nutrients which are absorbed by the specimen's roots.  The roots grow (along with the petioles) from the nodes along the stem's length.  In many Anthurium species those roots never touch the soil but dangle in the air since many species grow suspended on the trunk or limbs of a tree.  Anthurium sagittatum is terrestrial and rather than growing in the forest canopy grows in the soil.  Along the length of the stem which is short there can be found nodes separated by internodes which are also short.  The internodes typically measure 1.5 to 3 cm in diameter.  The internodes are simply a stem segment between two nodes.  The roots of Anthurium sagittatum are light brown to brown in color.

The stalks that support the leaves are known as petioles (detail photo, left).  Despite common misconceptions the petiole is not the "stem", a term commonly used incorrectly by plant collectors.  The petiole is simply a stalk that connects the leaf blade at the top of the petiole to the stem at its bottom.  The petiole grows from a bud on the stem and transfer water along with nutrients from the stem to the leaves.  The blades then convert carbon dioxide in the air into oxygen for other living organisms such as humans and rain forest animals to breathe. 

The petioles of Anthurium sagittatum are tinged violet-purple and are "D" shaped plus faintly ribbed on the upper surface (adaxially).  The description "D" shaped refers to the petiole when viewed as having been cut as a cross section.  Once cut the upper surface can be seen as flat while the balance of the petiole is terete (round) making it appear as a capital letter D,  That upper surface is both somewhat flattened and sulcate.  The botanical term sulcate may indicate either a channel that runs along the upper surface of the petiole or fine parallel grooves that run along that surface.  The petioles are angular winged and may possess as many as 8 wings (see photo, above right).   The base of the petioles are tinged reddish brown and are sharply 3 ribbed but may also have 4 to 5 sides as they intersect the stem.  The petioles may also be striate which indicates they possess parallel lines (not grooves) that run along the petiole's axis (length). 

All Anthurium species possess an organ known to botanists as a geniculum (see photo, below left).  The word originates from the scientific term geniculate which means to be bent sharply like a knee.  The geniculum is found at the petiole's apex (top) just beneath the connection to the blade and is normally slightly larger than the diameter of the petiole.  The geniculum often appears as if it were a a slightly swollen "gland" and on Anthurium sagittatum is somewhat lighter in coloration.  The geniculum acts as a knee or elbow and permits the leaf to rotate and change its orientation in order to better collect light.  In the majority of Anthurium species the geniculum is easily observed but in a few it is somewhat obscure but almost always can be detected by feel.

The cataphylls are bract-like modified leaves that surround any newly emerging leaf blade and its petiole.   The purpose of the cataphyll is primarily to protect the new leaf as it develops,  The cataphylls of Anthurium sagittatum are bluntly ribbed once they emerge and are semi persistent as well as split in half once they age.  The cataphylls of Anthurium sagittatum are are triangular lanceolate in shape.  Triangular lanceolate indicates the cataphylls are both triangular and lance shaped as in the shape of a knife.  They then age to a tannish brown coloration (see photo, right) and persist at the base of the petiole for a period of time before finally becoming deciduous and dropping from the plant. 
 
Anthurium species are members of the larger plant family known as Araceae.   Members of the genera of Araceae are also commonly known as aroids.  An aroid is a plant that reproduces by producing an inflorescence which consists of a spathe and spadix along with other near microscopic parts.  The inflorescence is supported by a stalk known as the peduncle which is terete (round) and is either shorter or approximately as long as a petiole, 

Many people believe the spathe is a "flower" which is incorrect. The spathe is a modified leaf whose purpose is to protect the spadix at the center of the inflorescence during development.  When sexually mature there are tiny flowers found along the spadix but the spathe is not a flower.  Aroids are divided into two basic reproductive sections or groups.  The first produces a bisexual inflorescence with male and female flowers mixed together along the length of the spadix.  The second is known as the unisexual group and includes those aroids that produce an inflorescence with bisexual flower zones.  Anthurium species are bisexual. 

Anthurium differ from Philodendron species since all Anthurium produce perfect flowers containing both male and female organs while Philodendron produce imperfect flowers containing only a single sex.   When an Anthurium is "in flower" the reference is to the tiny flowers containing both male and female sexual parts that grow on the spadix at the center of the inflorescence.  To help prevent self pollination nature has designed the female flowers to be receptive before the male portion of the flower produce their pollen so in most cases an insect must bring pollen from another plant.

At female anthesis when the female flowers are produced the spadix produces female receptive flower parts followed by sexually active male and sterile flowers.  The flowers are almost microscopic and since they are bisexual grow mixed together in a single flower all along the spadix.  If the female flowers are pollinated by an appropriate insect which is normally a beetle from the genus Cyclocephala that carries pollen from another specimen at male anthesis the spadix will begin to grow berries.  In many Anthurium species it is possible for the plant to self pollinate and it is theorized the wind may play a part in self pollination.

These pollinators are drawn to the plant since it produces a "perfume" known as an pheromone once it reaches anthesis.  The beetles can detect the pheromone from distances as great as 200 meters (600 feet) away and fly a zig-zag pattern through the forest to locate its source since the wind does not follow a straight-line path through the forest.  Along with a mate the beetles are drawn by both the fragrance and the heat of both thermogenesis (heat rise) and the "glow" of infrared heat which the beetles can "see" with their antennae in the dark.  The beetles are also drawn to the inflorescence since the pollen being produced is a food source in the form of lipid protein. 

For more detailed information on how aroid species reproduce please read this link:  Aroid pollination

The Inflorescence of Anthurium sagittatum is normally erect but may be re-curved as can be seen in our photos . The spathe is papyraceous (paper-like) and persists (does not quickly fall off) when in fruit.  The spathe is ribbed and is green to yellowish green and may be tinged purplish as it ages.  The spathe is also matte on the inside and is spreading in shape.  The spathe may be tinged reddish purple and is weakly glossy on the outside.  The spadix is a medium to pale yellow green and is semi glossy but may change to purplish as it matures.  

Joep states that Anthurium sagittatum specimens are often in flower in French Guiana and once pollinated produce deep purple berries (fruit) which contain the seeds of the species.  Once pollinated the inflorescence is then known as an Infructescence.  The berries are rounded to obovate (oval and to oblong) and are eaten by birds and other rain forest animal which spread the seeds through the rain forest in their droppings.

In in several published papers including a study entitled The Reproductive Biology of Euglossine-pollinated plants in the natural reserve Nouragues, French Guiana by Heiko Hentrich done in French Guiana, the author states "The reproductive biology of several Euglossine-pollinated species of an understory community in the natural reserve Nouragues in French Guiana were studied. The first two chapters deal with the pollination biology of three sympatric, co-flowering aroids (Anthurium sagittatum, Anthurium thrinax and Spathiphyllum humboldtii). Each of the studied species possessed a specific floral scent bouquet that attracted species-specific pollinators. The pollinators were male Euglossine bees, which collected floral scent at the spadices of the plants. Floral scent might be a major factor in the reproductive isolation of these plant species. " 

Within the genera Euglossini there are some 200 Neotropical bee species known as either "Orchid Bees" or Euglossine bees   Five genera are known to be found exclusively in Neotropical America (South and Central America).  The bees are characterized by a very long tongue and the behavior of the males of a species is known to be drawn to the pheromones (fragrances) from many flowers and other objects such as dead wood.  These bees store what they collect on their modified hind legs.   Bees in the genera Euglossini include vividly colored bees with colorations of metallic blue, greens and bronzes and the bee species are known to serve as orchid pollinators in South American rain forests.  Utilizing their long tongues which measure up to 4 cm (1.6 inches) in length these bees are known to pollinate close to 700 species of tropical orchids.  These bee species are are common in lowland forests where the majority of Anthurium sagittatum specimens are found.

However other experts are convinced these bees may only be drawn to the pheromone of Anthurium species and in fact only infrequently pollinate aroid species.  An observation of any insect visiting a particular plant species requires careful study before any scientific conclusions can be drawn.  The insect may only be drawn to the pheromone (perfume) and does not actually transfer pollen from one plant at male anthesis to another at female anthesis.  In a personal note from noted aroid expert Julius Boos he wrote,  "Euglossine bees are small and are about 1/3 the size of a honey bee.  These metallic bees are found in the tropics.  They are attracted to special odors given off by some aroids and orchids, and are assumed to be the pollinators of some aroids, Spathiphyllum cannifolium (see Deni Bown`s book on this), and maybe some Anthuriums, etc." 

Although other references can be found indicating Euglossine bees are primary pollinators of Anthurium species it is well known that many Anthurium sp. are capable of self pollination and an insect simply walking along the spadix may transfer pollen from the male flowers to the female flowers.  Casual pollination is not the same as a primary pollinator. 

To bring some clarity to this subject I asked my friend French aroid pollination expert Dr. Marc Gibernau (GHEE-ber-no) of the University Paul Sabatier in Toulouse, France if Euglossine bees were involved in Anthurium pollination.  Marc responded, "Euglossine bees are primary pollinators of many Anthurium but not all."  He then continued ".... apparently some species may be beetle pollinated (curculionid weevils) and one species is suspected to be hummingbird pollinated.  But pollination ecology in Anthurium is poorly documented".  At the end he stated only 15 Anthurium species may be pollinated by bees.

As a result of both Julius' and Marc's notes it may be premature to assume bees from the genera Euglossini are in fact a "primary pollinator" of very many Anthurium species at all.  Certainly these bees do visit some Anthurium species but beetles from the genera of Cyclocephala are likely to be primary in the pollination process of the majority of Anthurium species.  The jury is still out on this subject.

Julius' mention of Deni Bown's book is a reference to her excellent text Aroids, Plants of the Arum Family which is available at many book stores.

Our specimen shown in all the photos on this page was acquired from the collection of the Missouri Botanical Garden in St. Louis, MO.  It was grown from an offset of specimen 81084 which was originally tagged Anthurium rubrinervium. The specimen was collected by Dr. Tom Croat and was presented to us on June 19, 2009. 

For a better understanding of variation within plant species please click this link  Natural variation within Aroid and other plant species.

 

 

 

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Aroid Pollination!
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