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.
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.
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.
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.
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:
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.
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.
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.
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.