This discussion includes Alocasia zebrina, "Alocasia Reticulata", Alocasia tigrina and Alocasia 'Tigrina Superba'.
Only Alocasia zebrina is an accepted published scientific name

 

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Alocasia zebrina reticulata form

Incorrectly Alocasia zebrina cv. reticulata or Alocasia reticulata

Published in 1863, Alocasia zebrina (alo-CAY-see-ee) is exclusively found (endemic) to a single island in the Philippines.  The reticulated leaf form which has a pattern on the leaf blades appears to be an unusual variation of the species that has not been found in nature.   Alocasia zebrina reticulata form simply possesses the unusual leaf reticulation with a more elongated blade shape.  Other forms including one sold commercially as Alocasia Tigrina also demonstrate the elongated leaf blade.  As the blades of the reticulated variation mature the pattern fades until it is barely noticeable.

The species Alocasia zebrina is found on the island of Luzon in primary rain forests at elevations of 100 to 400 meters (330 to 1,300 feet).   A. zebrina is typically found in nature growing in wet humus covered soil adjacent to boulders in the shade of the forest.

A. zebrina possesses a short caudex with petioles that grow to approximately 92 cm (36 inches) long or longer although juvenile specimens will be much shorter in height.  The name "zebrina" was granted as a result of the pattern on the petiole which collectors commonly incorrectly refer to as a "stem".  A caudex is the axis or base which is the true stem of the plant.    The stem of any aroid is not the support for any individual leaf blade but is the central axis and base of the plant where the petioles that support the leaves as well as the roots emerge. 

The confusion over the term "stem" used incorrectly as a leaf support appears to come from roses.  The rose flower is supported by a non-woody segment of stem but the florist removes the leaves which have short petioles along with the "thorns" from a portion of that stem.  The "thorns" are not true thorns but are instead simply modified stems.  Since it often comes cleaned in the box many appear to forget the stem is not the support for the roses' leaves and misapply the term to other plant species. The stem of the rose supports a terminal flower and not any individual leaf blade.  Take a look at any rose and you'll see the leaves are supported by petioles.

The stems of Alocasia zebrina are an un-branched sympodium.  Sympodium refers to the "symphony" or rosette-ike form of the branching growth of the new petioles which is similar to the arrangement of the petals of a rose. The stem is rhizomatous (a rhizome) and runs just beneath the surface of the soil producing new plants adjacent to the parent from nodes along the stem.

In some Alocasia species the newly emerging leaves and petioles are protected by a cataphyll.  A cataphyll is a sheath-like modified leaf that envelopes and protects each new leaf as it develops.  Rather than a cataphyll Alocasia zebrina produces new petioles with blades that emerge from a sheath on the side of the petiole known as a petiolar sheath.   Each new petiole emerges from these "wing-like" sheaths on the side of the previous petiole (see photo, right).

Alocasia zebrina is known to be a highly variable species which is capable of producing more than one leaf form.  Variation is common among aroid species but as aroid expert Julius Boos explains later in this article variation is especially prominent within the genus Alocasia.  Botanists including Australian Alistair Hay have been working to reclassifying numerous specimens previously thought to be individual species into single merged  names as a result of natural variation.  Some of these advances are as a result of the increased use of DNA to explore the genetic makeup of plant specimens which will result in some previously accepted scientific names being sunk into synonymy under other species' names.  

The incorrectly used commercial name Alocasia 'reticulata' is improper as a trade name as pointed out later in this article since the name is not registered as a cultivar with the International Aroid Society which serves as the governing agency for this group of plants.  Once a registration is filed a plant grower/seller may use single quotes to indicate the plant has been properly registered.  But since no registration has been filed the use of single quotes is inappropriate.   For many years plant grower/sellers have failed to observe the rules laid down for their own industry and known cultivars of many plants are commonly mislabeled by a large number of grower/sellers.  

Even more unfortunate is the fact many grower/sellers also often attempt to display the name in italics or give the plant a Latin sounding name.  The use of Latinized names or italics is reserved for scientifically described species and is not an accepted practice for commercial plant names.   It appears some grower/sellers would prefer to completely throw out the rules of either botanical science or horticulture causing a great deal of confusion among plant collectors.

Additionally, no one is certain where the commonly used name of a similar sport, Alocasia tigrina originated.  Some sources indicate "Alocasia tigrina" is a species name and attempt to display it in italics but according to aroid botanist Pete Boyce in Singapore there is no such plant as "Alocasia tigrina" in science, "The name Alocasia tigrina does not exist. It has been applied to Alocasia zebrina in the trade for the clone with the very well-marked petioles.  Alocasia zebrina is endemic to the Philippines and restricted to the islands of Luzon, Mindanao, Leyte, Samar, Biliran and Alabat. It is easily distinguished from all other Philippine Alocasia species by the rather narrowly sagittate leaves with striped petioles and rather long acute posterior lobes bearing lamina to the sinus but not or only very narrowly peltate."   A sagittate leaf is one that is arrow shaped.  Peltate refers to the position the petiole is attached to the leaf blade near the center.  The petioles of Alocasia zebrina are virtually identical to that of Alocasia zebrina reticulata form but the leaves are quite different.

Horticulturists and plant collectors have attempted to give variations of species in the genus Alocasia totally new scientific sounding names in the past which have never been scientifically accepted.  Although there is nothing wrong with a collector placing a unique tag in the pot of a unique specimen that does not mean the plant is a new or different plant species.

This information by botanist Alistair Hay points to the problems caused by plant grower/sellers when they improperly cause collectors to confuse a common name with a scientific name, "I think this is a mess!  Not your page, just the general situation re this name.  First, is it really a sport - i.e. a vegetative mutant growing out of and taken from something else. I would have thought direct evidence of this status would be required. I suspect it is a variant seedling of A. zebrina, though of course it could be hybrid of some sort.  Second, as far as I can see (and as you say) this species name seems never to have been published properly.  I just tried searching the IPNI database but it keeps timing out, but I don't recall seeing this name as a valid species name when I was looking at Alocasia in detail.  Third, I don't think it can be valid as a cultivar name. Latin species names can only be transferred across as cultivar names if it can be demonstrated that the originally published "species" is a cultivar. If, as we suspect, this has never been validly published as a species name, it is invalid as a cultivar name simply because it is Latin.  Fourth, if the plant was released as a cultivar with a "pseudo species" name, it should be re-named properly (i.e. with an English or other modern language epithet and published with a description and pic either with the introducer's consent, or not, if someone has released a cultivar with an invalid name, they have had their shot at it and it would be open to anyone to rename the plant, though I do think that should be done properly: i.e. publishing it in either Aroideana or the IAS Newsletter with a pic and description. These sort of messy situations need a formal determination by the ICRA and possibly consultation with the ISHS commission for cultivar registration and nomenclature."  IPNI refers to the International Plant Names Index and ISHS refers to the International Society for Horticultural Science.

 

The confusion appears to date back some years.  Alistair pointed out, "I searched Google books for Alocasia reticulata and got only one result which can't be viewed, but the name allegedly appears in Wood, Allen H. (1941), Try These Indoors, Published by Hale, Cushman and Flint."   "Try Those Indoors" was a book about houseplants. 

The name reticulata was again briefly described as a variation of Alocasia in the 1983 International Aroid Society journal Aroideana, Volume 7, numbers 3 and 4 by David Burnett where he appears to use Alocasia 'reticulata' only as a horticultural name.  David wrote, "This plant seems to have been released by Fantastic Gardens, Florida, sometime in the last ten years.  It is still uncommon in the USA and virtually unknown elsewhere.  It's origins are, so far as I can determine, unknown.  I doubt that it is a species and it is not likely be be a hybrid.  Perhaps it is simply a sport or varietal form of a species.  I have placed it among the Philippine Alocasia for reasons that I find extremely difficult to explain in words.  Somehow the plant evokes a relationship with A. zebrina and A. 'Tigrina Superba', yet; some of its characteristics are distinct from both.  I have not had sufficient experience with the plant to describe it, so I shall let the photograph speak for itself for the time being."  In his discussion David offered no measurements and no definitive information.

Following my request for information from members of the aroid discussion group Aroid l, I received this response from former IAS president, Scott Hyndman, "When I first saw this Alocasia at the now long ago closed Fantastic  Gardens Nursery of Miami in 1981 it was sold as Alocasia zebrina cv reticulata."  However, as Julius explained early in this article, the use of "cv" in relation to this plant is improper since no such cultivar has ever been registered. 

All Alocasia species are members of the larger plant family known as Araceae (uh-RAY-see ee) commonly called aroids. An aroid is a plant that reproduces via the production of an inflorescence which  is known to science as a spathe and spadix. The inflorescence is supported by a stalk known as a peduncle.

In Alocasia species the inflorescence is more correctly called a synflorescence since the inflorescences grow as multiples.  Pete explains, "A synflorescence is a branching unit where a series of inflorescences are generated one after another with no return to vegetative or foliage-leafy units. The inflorescences arise in sequence one after another and usually open in sequence." 

Although many individuals try to call the inflorescence a "flower" the spathe is closer to being a "flower holder". The spathe is a modified leaf or bract that surrounds the spadix which truly holds the flowers. The flowers of Araceae are very small and grow along the spadice's length which is a spike on a thickened fleshy axis. If you explore the spadix with a magnifying glass when it is at sexual anthesis and is ready to be pollinated you can see the near microscopic flowers.

The spathe is shaped like a  hood which opens during the reproductive cycle known as anthesis.  Berries containing seeds will develop on the spadix provided the female flowers are pollinated.  In botany a bract is a specialized leaf that is associated with the reproductive structure of a plant. The spathe cannot be considered a flower since it contains no sexual parts including anthers, pistils, stamens, nor stigmas.   For more information on aroid pollination please read this link:  Natural pollination in aroids.

Alocasia species are unisexual since the female and male flower regions are divided into unique zones. Based on information published by Peter Boyce  the spathe of an Alocasia species is divided into a convolute (twisted) spathe plus a thicker lower portion which surrounds a zone on the spadix containing female flowers and known as the female floral chamber.  Although the upper portion will eventually drop from the plant the lower portion remains around the spadix once the upper spathe dies.  This lower chamber turns into a fruiting region which will eventually produce berries containing seeds. The two zones of the spathe can be recognized by a constriction making the lower part containing the floral chamber appear globose or rounded to ovoid (see photo right).   There is also a third zone of sterile male flowers on the spadix found between the male and female zones. Typically the spathe constriction is level with this zone division. As a result the female flower zone is isolated from the male zone.

You can read Pete's published work here: http://www.aroid.org/genera/alocasia/alocthailand.pdf

As anthesis begins the spadix-spathe constriction loosens allowing pollinating insects to access the pistils of the tiny flowers. Those insects gather pollen from another inflorescence currently at male anthesis and carry the pollen to an inflorescence at female anthesis. The inflorescence can produce a detectable scent in some species that is fragrant but may also mimic the odor of decaying flesh. This fragrance is known as a pheromone and once carried on the breeze serves as an attractant to the any assigned pollinating insect species. Once female anthesis ends the spathe constriction closes to grip the spadix and the pheromone ceases to be emitted.   Male anthesis occurs once female anthesis has completed and only then is pollen produced. The pollen produced by the male flowers is mealy and once it begins to drop is collected between the lip of the limb and the spadix in a trough-like fold that develops between the spadix and the limb's base. The limb is the edge of the spathe (see photo, above).

The upper portion of the spadix also forms a sterile region which is often thermogenic as is the male flower zone.  Along with the scented pheromone thermogenesis is considered a major attractant to any pollinator since it offers a place of warmth in the cool of the rain forest night. A thermogenic region is one capable of producing heat due to the chemical reaction of salicylic acid. In some species this heat zone can be felt by holding an opened palm near the spathe and spadix during anthesis. The inflorescence also produces infrared heat which to an insect appears in the form of a "glow" not visible to the human eye which is clearly visible to the pollinating insect. As a result the insect can "see" the "glow" of the spadix at sexual anthesis in the darkness in a way similar to a pilot searching for the glow of the landing lights of a runway.

Due to natural variation the blades and spathe may not always appear exactly the same from specimen to specimen.  Additional information from aroid hybridizer LariAnn Garner noted, "While the inflorescences are very similar, the leaf texture is markedly different from both "reticulata" and "tigrina".  The petioles are more definitively striped rather than just coarsely mottled, as "tigrina" and "reticulata" are.  The leaf blades have a thickness, almost a leathery texture, that both of the others lack completely.  The leaves are discolorous (upper surface and lower surface different shades of green), which is similar to "tigrina" but unlike "reticulata", whose leaves are concolorous, and the venation is not prominent at all.  The width of the leaf blades is significantly greater, especially in mature specimens, than in either of the other two.  If you saw all three plants side by side, you'd likely conclude that "reticulata" is a sport of "tigrina", not zebrina!"

At present, adequate scientific information has simply not been published to determine a positive status for Alocasia zebrina reticulata form.  It does certainly appear the specimen is a variation of Alocasia zebrina, but lacking verified evidence published by a qualified botanical scientist, a scientific determination appears not yet complete.  This is one of Alistair's most recent messages, "As I said, the botanical reticulata could be used as the cultivar epithet as in Alocasia 'reticulata', provided the species or variety name was given to this clone (i.e. it is equivalent to a cv) and not to a range of similar clones. However, to qualify for that, it must go back in its usage to prior to Jan 1 1959. If it is later than that, it cannot be used as the cv name.  It seems pretty clear that this is not a distinct species, and botanical variety is just not an appropriate category for a horticultural thing like this: it needs to be given a cv name!"  And in one final email Lord Alistair had this comment, "A. tigrina has no botanical merit and is simply a particularly attractive form of zebrina which should be recognized as a cultivar if it is a clone. The same applies as before, if it is a clone and the name has been published before 1959 in a way which meets the conditions for establishment of a cultivar name, then it can be transferred across as a cultivar name Alocasia 'Tigrina'. Ditto 'Tigrina Superba'.   However, I have tended to take a rather conservative view of species definitions in Alocasia - i.e. not splitting off slight variations as species, and others might disagree. The view of Aroid botanists in the Philippines may be different!" 

For now, It appears best to call the reticulated variation of this plant  Alocasia zebrina reticulata form.   As Alistair noted, the name for this specimen "is a mess".   This post made July 9, 2008 on Aroid l by  Pete Boyce offers some insight, "As you know, Alistair Hay in his herbarium-based account of Philippines' Alocasia (Gardens' Bulletin Singapore 51: 1-41 (1999)) treated A. zebrina as a variable species and included under that name A. wenzelii. He made no mention of the name A. tigrina (or A. zebrina tigrina) as this name and any combination thereof has never been formally published and thus from a strict botanical standpoint dos not exist. Goerverts et al. include a further name as a provisional syn. (A. liervalii) but without further discussion.  Not withstanding the strict application of published names it is clear to anyone who grows A. zebrina that there are several conspicuously different (but likewise clearly allied) entities in cultivation, among which the form with reticulated venation is particularly striking. What of course is needed is a comprehensive field study to try to untangle these cultivated clones and see where they may have originated."
 
Our specimen in was a gift from avid collector Teri Baber and is grown in a well draining soil mixture that is kept damp.   The specimen is grown in indirect, yet relatively bright mottled light.  The species and variations are known to go dormant at temperatures below 12.75 C (55 degrees F).  Protect your plant from any freeze.

My thanks to aroid expert Julius Boos for his assistance as well as to Pete Boyce and LariAnn Garner http://aroidiaresearch.org/      My sincere appreciation to Alistair Hay for checking this page and offering his valuable input. 

Although the parent species Alocasia zebrina is now apparently rare as a result of over collection in the wild this specimen is commonly available to collectors due to the process of tissue culture (cloning). 

One personal note of explanation:  Lord Alistair Hay legitimately possesses his title as a result of family heritage. He rarely uses the title with his name but some in the aroid community have referred to Alistair, now retired, as Sir Hay.  He recently informed me in a personal email he is not a  "Sir".  Those of us that appreciate Alistair's work use the title due to our respect for what he has done for the study of aroid botany.

Alistair resides several hours south of Sydney, Australia and currently grows Brugmansia.  His website address is: http://www.MerooMeadowPerennials.com.au/