Anthurium watermaliense Hort. ex L.H. Bailey & Nash, Anthurium watermaliense, Black Anthurium, Exotic Rainforest rare tropical plants

Anthurium watermaliense Hort. ex L.H. Bailey & Nash

Common name: Black Anthurium

All data was taken from the published works of Dr. Thomas B. Croat Ph.D., P.A. Schulze Curator of Botany of the Missouri Botanical Garden in St. Louis, MO in his Annals of the Missouri Botanical Garden 1983, Volume 70, #2

Although published in horticulture, on scientific sources Anthurium watermaliense often appears to be only a natural hybrid. The name is valid in horticultural literature but not on some scientific sources. The Royal Botanic Garden Kew's International Plant Names Index (IPNI) International Plant Names Index does not recognize the name as a published scientific species. However, on the Royal Botanic Garden Kew website World Checklist of Selected Plant Families World Checklist of Selected Plant Families , the Kew's CATE Araceae and the Kew's World Checklist of Monocotyledons World Checklist of Monocotyledons the name is an accepted scientific name. Some botanists speak of Anthurium watermaliense as a described species while some do not. On the weekend of December 11, 2009 I asked Dr. Croat his opinion and was assured the plant is a valid species common to parts of Central America. Dr. Croat is America's leading aroid botanist.

The aroid is very common in Costa Rica and Panama and grows terrestrially in the soil. Anthurium watermaliense has been noted to also have been collected in Colombia but appears to be uncommon in that country.

Anthurium watermaliense is easily recognized by the following characteristics taken from a synopsis of the species by Dr. Croat, "Anthurium watermaliense is an atypical member of section Pachyneurium and is not generally confused with any other species in Central America. It can be recognized by the ovate-triangular to sub-3-lobed leaf blades, the broad, frequently dark purple spathe, green to purple, stipitate spadix with long-exscrted stamens, and yellow to orange berries." "Stiputate spadix" refers to a relatively unusual stalk not seen in all Anthurium species known as a stipe. The stipe separates the spathe and spadix and is helpful in recognizing the species. A more detailed explanation follows along with photos to point out the location of the stipe.

The nomen "watermaliense" comes from the name of the city Watermall, Belgium where Anthurium watermaliense was first taken after collection, reportedly in Colombia. The horticultural name (Hort.) Anthurium watermaliense was published in 1914 by Liberty Hyde Bailey Jr. (1858-1954) in his Cyclopedia of American Horticulture, a non-scientific publication.

A naturally variable specimen, Anthurium watermaliense is commonly known by the name "Black Anthurium" due to the deep coloration of its dark purple inflorescence, not the color of the foliage. There is also another Anthurium known by the common name "Black Anthurium" which is a different species, Anthurium cabrerense. A. cabrerense is a cool-growing Anthurium from the high Andes of Ecuador and the spathe of A. cabrerense is a bit darker than that of A. watermaliense but both have that same purple-brown coloration that almost looks black in the correct light.

Placed in Anthurium section Pachyneurium, the group of Anthurium species which includes all the "bird's nest" forms, Anthurium watermaliense is found from sea level to approximately 2500 meters (8000 feet) in wet pre-mountainous rain forests with the majority of specimens found at elevations of approximately 750 meters (2500 feet) or less. A "bird's nest" form is an Anthurium specimen which grows in a rosette shape with the leaves extending outward from the stem.

In 2005 Dr. Croat responded to a question on the aroid forum Aroid l regarding the section placement of Anthurium watermaliense, "I have placed this in Section Pachyneurium owing to its involute vernation but it is an unusual member of that group for sure. I have often wondered if it might not be itself of hybrid origin." Dr. Croat then continued, "There are about a half dozen of these cordate odd balls, A. standlyi, A. schottii, etc. Some are quite attractive." Cordate is a reference to the heart shaped leaf and involute vernation refers to the way both margins (edges) of a new leaf blade are rolled inward similar to two tubes as it begins to emerge from the cataphylls which protect any newly emerging leaf blade.

Vernation simply indicates the coiled arrangement of young leaves as they emerge. My good friend and aroid expert Leland Miyano in Hawaii explains further, "When Dr. Croat points out the possibility of a hybrid origin and the biogeography of Anthurium watermaliense, there is a Panamanian Anthurium in the section Pachyneurium that can have a deep, black purple spathe (this feature is variable to clone). That species is Anthurium luteynii, a Panamanian endemic. I am not implying any parentage...but one has to find a genetic source of this dark purple spathe within the geographic range of wild populations of Anthurium watermaliense if it is indeed of hybrid origin. Also, as Dr, Croat points out, it is unusual to have cordate species within the section Pachyneurium. Anthurium luteynii, is a birds nest form, not cordate at all."

An aroid, all Anthurium species reproduce via the production an inflorescence. The primary parts of the inflorescence (see photo left, below) are the spathe and spadix. The entire inflorescence of Anthurium watermaliense stands erect on a stalk known as the peduncle which is dark purple-violet in color. The spathe is normally a dark purple-violet but may also be green tinged with purple depending on the stage of development. The spathe possesses a lanceolate-triangular shape (lance-shaped somewhat resembling a triangle) and is reflexed or turned back as well as twisted. The spadix

also stands on a stipe. The term stipe is a adjective of the term stipitate and indicates there is a stalk that supports some other structure. You can clearly see the stipe in the photo to the right as well as the photo above of a newly forming inflorescence. Please notice that in both cases the spathe has begun to reflex (turn backwards away from the spadix.

Leland explains further, "In looking at the detail photos of the inflorescence, notice that the spadix is stipitate. In other words, the spadix is supported by a stipe...the bare portion below the flowers and above the spathe. In the section Pachyneurium the presence of a distinct stipe is rather rare so it is a good feature to point out." In the case of Anthurium watermaliense the stipe emerges white but soon darkens to match the color of the peduncle.

When an Anthurium is "in flower" the reference is to sexual anthesis at which time the spadix produces tiny male, female and sterile male flowers that grow on the spadix. The spathe itself is a modified leaf and is not a "flower". The spadix may be purplish when young but typically turns green to yellowish green or tan-white tinged purple-violet as it ages (see photo below). The spadix vaguely resembles an elongated pine cone and when mature both the spathe and spadix turn so dark in color they appear black, thus the common name "Black Anthurium". The spadix is a spike on a thickened fleshy axis which can produce tiny flowers.

During sexual anthesis the tiny male flowers produce pollen and the very small female flowers become receptive to pollination, however, most aroids are cleverly divided by nature to keep the aroid from becoming self-pollinated. The female flowers reach sexual anthesis first and once they have completed the process the male flowers begin to produce pollen. Nature's preferred method for pollination is to have insects (almost always a beetle from the genus Cyclocephala) to collect pollen from a plant of the same species at male anthesis and carry it to the female flowers of another specimen of the same species at female anthesis in to keep the species strong. Once pollinated the spadix produces berries which in the case of Anthurium watermaliense are ovoid to obovoid in shape and yellowish to orange when mature and will contain the seeds of the Anthurium. For additional information on aroid sexual reproduction please refer to this link: Aroid pollination

The deeply lobed cordate leaf blades of Anthurium watermaliense typically measure 30 to 60 cm (1 to 2 feet) and stand erect on a long petiole. The blades are sub-coriaceous (less than leathery) to the touch, glossy to semi-glossy and bi-colorous (two colored) but are paler in color on the abaxial (underside) of the blade. The primary veins are sunken but weakly raised on the adaxial (upper) surface but are more prominent on the abaxial (lower) surface. The primary veins on the blade's underside are also darker in color. The midrib is narrowly rounded and slightly paler in color than the blade. The primary veins are sunken but weakly raised on the adaxial (upper) surface (see photo, left). However, they are more prominently seen on the abaxial (lower) surface.

All Anthurium species also possess a collective vein which runs near the margin (edge) of the leaf blade. (see photo, top of page) Collective veins arise in pairs on each side of the leaf vein and are simply the union of part of all of the primary lateral veins that extend all the way to the apex (end or tip) of the blade. Collective veins are submarginal vein (not touching the edge) that lie parallel as well as near the leaf margin (edge). The primary lateral veins run into the collective vein which may be a continuation of a primary lateral leaf vein (often the lowermost or the uppermost basil veins). Collective veins may be observed in Anthurium, Syngonium, Alocasia, Colocasia, Xanthosoma, Pycnospatha, Arisaema, Protarum, and some Amorphophallus and other genera but are never found on a Philodendron species.

Every leaf of an Anthurium is supported by a petiole (photo, right). The petiole is the stalk that attaches the leaf blade to the stem. The petiole extends upward and outward from a node on the stem to the point where it joins with the leaf blade. The petioles of Anthurium watermaliense are terete (rounded) to just less than rounded, may be very slightly speckled and slightly flattened as well as canaliculate on the adaxial (upper) surface (photo, right). Additionally, the petioles are weakly sulcate. Sulcate indicates either a canal known as a sulcus or having numerous fine parallel grooves running parallel along the petiole and canaliculate indicates a channel running the length of the petiole.

Anthurium watermaliense cataphyll and stem, Photo Copyright 2008, Steve Lucas, www.ExoticRainforest.com Despite a tendency for collectors to call a petiole "the stem", that is scientifically inaccurate since the stem and petiole are completely different. The stem is at the base of the specimen and is the main trunk from which the petioles arise from stem's nodes. Along the stems are the nodes and the segment of the stem between two nodes is known as an internode. The internodes of Anthurium watermaliense are short. The stem supports the petioles and thus the leaf blades as well as stores food, water and nutrients for the plant and carries the water and nutrients to the petioles and thus to the blades. The cataphylls, which are the bract-like modified leaves that surrounds any newly emerging leaf blade, are canaliculate (possessing a channel along the axis). Once dried, the cataphylls remain as a fibrous material somewhat similar to that on a coconut husk (see photo, left).

At the very top of the petiole (see photo below) is found a "swollen" knee-like organ common to Anthurium species known as the geniculum. Aroid expert Julius Boos explains further regarding the purpose of the geniculum, " the geniculum acts like a ''wrist'' and actually allows the leaf blade to turn or rotate to align itself with the light source and occurs only on some aroid genera including Anthurium and Spathiphyllum but not on others." In Anthurium watermaliense the geniculum is also narrowly sulcate (grooved).

Anthurium watermaliense geniculum, Photo Copyright 2008, Steve Lucas, www.ExoticRainforest.com

Our specimen was acquired from the Arenal Botanical Garden in Costa Rica as a very tiny seedling in the summer of 2005. Since A. watermaliense is a terrestrial aroid found growing in the soil, a specimen should be given well draining soil and kept slightly damp most of the year.

Anthurium species are known to be highly variable and not every leaf or inflorescence of every specimen of Anthurium watermaliense will always appear the same. This link explains natural variation and morphogenesis within aroids and other plant species in non-technical language .
Natural variation

Aroid Pollination
As it occurs in nature

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