INTRODUCING AQUATIC PALMS by Jorge Monteverde, Buenos Aires, Argentina © January 2005 Reprinted with permission from the International Waterlily and Water Gardening Society's Water Garden Journal (ISSN 1069-5982). www.iwgs.org  Click images to enlarge

Euterpe oleracea Photo by Michael Calonje

INTRODUCTION

Some time ago I had the opportunity to read a very interesting article(1) by the expert Betsy Sakata (Hall of Fame IWGS 2001) from Hawaii, USA, in which she told about one of her favorite aquatic plants, Cyrtostachys renda Blume (sealing wax palm). She mentioned that there were other aquatic palms, but left discussion of them for another time, adding that their beauty and potential as water garden plants merited further study and widespread attention.

Chelyocarpus dinaerius Photo by Michael Calonje

Taking her passing comment as a challenge, I began to explore palms with the close attention suggested by Ms. Sakata. As the result of my curiosity I ended up investigating these monocotyledons, and realized they would contribute greatly to water gardening if I could precisely identify the aquatic species of this vast family of plants. The Family Palmae (Arecaceae) comprises over 1880 species, not counting varieties, distributed in 191 genera that grow all around the world, mainly in tropical and subtropical zones.

WHAT BOTANISTS TELL US

I immediately checked the indispensable reference by Dr. Christopher D.K. Cook, and got a little surprise: the renowned specialist says that the taxonomical Order Arecales (within which the Family Palmae resides) does not include any families that have aquatic species. That statement directly contradicted Ms. Sakata's respected opinion, and piqued my curiosity even more.

With the help of the internet, I was able to quickly update the information in Dr. Cook's book, which was first published in 1974, with a revised 2nd edition published in the 1990's. Two species are considered aquatic in the scientific literature available on the internet: Nypa fruticans Wurmb., native to the mangroves of Southeast Asia and Australia and naturalized in Trinidad and West Africa; and Ravenea musicalis Beentje, a freshwater palm from the ever-surprising island of Madagascar.

Nypa fruticans Photo by Jody Haynes, Montgomery Botanical Center

But not everything is on the Internet yet, and for a long time bibliographic research will be necessary. In this manner, from the different documents consulted, more species slowly came forth, some of them with a subtle differentiation that science has made within what we as water gardening aficionados would consider aquatic plants.

We know that plants which live all or part of their lives in close relation to an aquatic environment are called "hydrophytes" (C.D. Sculthorpe expounds on this subject; its reach, inaccuracy, and subjectivities). When we speak together as enthusiasts we don't usually get down to the details regarding whether the environment of one or another plant is what we call "lentic", of calm water, or "lotic", of moving water. But those who dedicate themselves to the study of Palms make the distinction.

It is common to find the term "rheophyte" in their writings which refers to plants (palms in this case) which live all or part of their lives in moving water, be it fast or slowly moving, and which have adapted strategies to deal with the difficulties of growing in those surroundings. We can conclude then, those plants which are categorized as rheophytes, are hydrophytes, but with a particular specialization.

Ravenea musicalis Beentje is one of those, as are Areca rheophytica Dransf., Chamaedorea cataractarum Mart., Geonoma linearis Burret., Hydriastele rheophytica Dowe & M.D. Ferrero, Pinanga rivularis Becc, Pinanga tenella (H. Wendl.) Scheff. var. tenella, and perhaps, though lacking full study, Dypsis crinita (Jumelle & H. Perrier) Beentje & Dransf., Geonoma brevispatha Barb. Rodr. and Pinanga subintegra var. beccariana (Furtado) C.K.Lim.

Chamaedorea cataractarum Photo by Gastón Torres Vera

Dr. Henk Beentje (pers comm.): "Dypsis crinita usually grows along riversides, so not really in the water; many seedlings do start in fairly fast flowing water (as rheophytes - with pliable underwater leaves) but I believe that when they grow larger they either are carried away by the current or collect stream debris around them and so become riverside plants!"

Not mentioned as rheophytes, but certainly existing in fully aquatic environment, we should add Dypsis aquatilis Dransf. and Raphia taedigera Mart.

So up to this point we have, according to the scientific literature, just 9 species and 1 variety of palm which are proven to be aquatic, with 2 species and 1 variety which are very likely to be aquatic, but lack full certainty botanically speaking.

I have not found additional references with sufficient scientific footing or coming from distinguished investigators, except a mention of Phoenix paludosa Roxb. (Scott Zona) in a context not thoroughly scientific. This palm, like others which I will mention later, thrives not only in aquatic environments, but also grows well in very different conditions, such as on dry ground in the Botanical Garden of Buenos Aires where there are two trees nearly a hundred years old.

BEYOND SCIENTIFIC DEFINITIONS As of now, the scientific evidence shows a small group of species of palms that are truly hydrophytes and rheophytes. But for our interest as aquatic gardeners, there are certainly others that fall into that category, though outside the strict criteria for scientific classification as aquatic. Cyrtostachys renda, the sealing wax palm, which started this article, is not technically aquatic but still fulfills our water-gardening needs, and so it could be called aquatic for our purposes.

Cyrtostachys renda Photo by Rich Sacher

While the previous portion of this article is clearly backed by scientific literature, the following does not presume the same rigor. It is the result of some investigation, some conversations with specialists, and quite a lot of compilation of pieces of information that were buried in various resources. My objective is to offer the widest possible range of information in an organized and useful manner to stand alone, as a base for other investigations, or to help us confirm personal experiences which will then permit us to delve more deeply into the potential for palms as aquatic ornamentals.

WHY HAVE PALMS BEEN OVERLOOKED?

What are some of the reasons we haven't thought of these elegant plants as ornamentals for our ponds and wetlands? Without thinking too hard, some ideas come to mind, and I am sure there are others:

· Lack of knowledge about these palms and their characteristics.
· The difficulty involved in obtaining seed or in growing some palms in temperate climates.
· The fact that many are difficult to grow under even the best circumstances.
· Nurseries don't offer aquatic palms.

In addition, the majority of the literature regarding aquatic ornamental plants and water gardening is from, and for, countries with rigorous climates such as the USA, Canada, and Northern Europe, so the specialized publications have not included palms.

Raphia sp. Photo by Gastón Torres Vera

It is also probable that the omission of palms from the water gardening literature is due to the ultimate size of the majority of the possible palms and the impression that they are too big to incorporate into the landscape of a pond. Some mature leaves can reach more than 8 meters in length! (and then there's Raphia taedigera at more than 18 meters!) Others are not easily adapted to the climates where most enthusiasts live. But from my point of view, that shouldn't impede our botanical curiosity. We should learn as much as can and embark on the adventure!

Even taking into account the truly enormous mature size of many of these species, they tend to grow quite slowly and can offer us much pleasure while they are young. There is also the possibility of managing the young plants with bonsai techniques, some of which are published on the Internet. However, not all of these palms are big, and some of the species mentioned could actually be considered small.

THE SPECIES

When we as water gardeners speak in general of aquatic plants, we think of those members of the plant kingdom which thrive in "watery environments", not just those plants which depend on flooded or completely saturated conditions, as would be the case with true hydrophytes. As gardeners, we would include those palms which are essentially terrestrial but which grow under conditions of long-term seasonal flooding, as well as those species that grow on the borders of permanent bodies of water. These plants are called helophytes. We also include species that in our experience seem to have adapted well in plantings in extremely wet conditions.

Seeing palms from this point of view, removing the rigorous lens of science, we widen our range and find a significant number of additional species which, in their natural habitats, are associated with permanent or seasonal wetlands. Of the species that I mention below, many are known as bog plants while others are at least moisture-loving.

Attalea cuatrecasana Photo by Michael Calonje

In this investigation I have identified 136 palms (131 species and 6 varieties) belonging to 51 genera. Eighty-three are from the Americas, 42 from Asia and Australia and 12 from Africa, including Madagascar. Expert review of the article previous to publication brought new species to light that I had missed. I have made an effort to make this list as accurate and complete as possible, but even so, there may well be species I have overlooked.

Mauritiella macroclada Photo by Michael Calonje

I have purposely left out many species that are considered climbing, vining, or leaning because they aren't interesting from the point of view of this article. Most of them belong to the large genus Calamus, the genus Daemonorops, with a few from the genus Korthalsia.

Click here for an alphabetical list detailing the species. Additional characteristics are included when possible, such as common names, origin, form of the leaves, mature height, trunk characteristic, habitat, etc.

PALM-LIKE PLANTS

Zamia roezlii Photo by Gastón Torres Vera

We have seen the palms which are either truly aquatic or at least adaptable to wet environments. But I don't want to end without briefly mentioning the most ancient living group of seed plants, which often go hand-in-hand with palms: the cycads. To the uninitiated, they look something like palms so I include them, but they are distinct and distant from the palms. These remarkable Jurassic survivors can also contribute to our water gardening enjoyment, particularly Zamia roezlii Lind. and Zamia chigua Seem. both from the wetlands of Colombia and Ecuador, and Zamia purpurea Vovides, J.D. Rees & Vázquez T. from Mexico. These plants must be considered moisture loving.

Aknowledgements

Carla Black in Panamá, who generously agreed to translate this article from Spanish, and Ángel Rodriguez, her husband, who introduced me to Dr. Jody Haynes.

Dr. Jody Haynes, Cycad Biologist at Montgomery Botanical Center, Coral Gables, Florida, for his generous and selfless technical revision, his immediate availability, and his contribution in providing indispensable information on the species, which in many cases had been mentioned only by name and origin. He also provided photographic illustrations and was always available for consultation.

Dr. Henk J. Beentje FLS, Editor Flora of Tropical East Africa, Royal Botanic Gardens, Kew. Botanist, recognized scientific authority in palm trees. For his generous and fast technical final review and valuable comments and corrections.

Paula Biles, Executive Director of IWGS; one of the first people to be interested in the article, and who encouraged me to continue working on it.

Walter Pagels, for his willingness to provide bibliographical information which was difficult for me to find in Argentina. He didn't have it either, but made the effort to get it.

Dr. Gastón Torres Vera, Córdoba - Argentina, Argentine member of the International Palm Society. He gave me the first list of palms which I used to begin this work. He also provided photographic illustrations.

Literature Cited

(1)Pondkeeper Magazine (Jan-Feb 2003).

Barrow, Sasha. Oct-94. In Search of Phoenix roebelenii: The Xishuangbanna Palm. Principes Vol. 38(4) 177-181.

Beentje, Henk J. Oct-93. A new aquatic palm from Madagascar Principes (Now Palms), Journal of the International Palm Society. Vol. 37(4) pp. 197-202

Cook, Christopher D.K et. al. 1974. Water Plants of the World. SPB Academic Publishing, The Netherlands. Reprinted and revised 1990-1996, changing the title to Aquatic Plants Book.

Dimitri, Milan J. 1978. Enciclopedia argentina de agricultura y jardinería, Tomo I, 'Descripción de las plantas cultivadas'. Editorial ACME. Buenos Aires.

Dransfield, J. 1992. Observations on rheophytic palms in Borneo. Bulletin de l'Institut Français d'Études Andines. 21(2) 415:432.

Henderson, Andrew - Galeano, Gloria & Bernal, Rodrigo. 1995. Field Guide to the Palms of the Americas. Princeton University Press

Sculthorpe, C. Duncan. 1967. The biology of aquatic vascular plants. Edward Arnold Ltd. (London).

Uhl, N. W. & Dransfield, J. 1987. Genera palmarum: a classification of palms based on the work of H.E. Moore jr. Kansas: The International Palm Society & the Bailey Hortorium.

Van Steenis, C. G. G. J.. 1981. Rheophytes of the world. Netherlands: Sijthoff & Noordhoff.

Velásquez, Justiniano. 1994. Plantas acuáticas vasculares de Venezuela. Universidad Central de Venezuela, (Colección estudios).

Zona, Scott. 2002. Morphological and ecological diversity of Palms. Fairchild Tropical Gardens.

Internet Resources

www.pacsoa.org.au/palms , www.rarepalmseeds.com , www.virtualherbarium.org , www.kew.org/data/monocots/palm_all.pdf , www.plantapalm.com