Huge and exotic, elephant ears fascinate

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We finally returned to Riverdale and much colder weather. With our irrigation system being turned off and nighttime temperatures plummeting, it is time to clean up the hoses and watering cans until spring. It is also time to dig up some of the tender perennials that cannot survive a New York winter. This past weekend, I went around the garden and dug up those caladium bulbs that I could still find.  They had already been dying away before we left and by Sunday, even their stems were mostly gone. My efforts, however, were focused particularly on the elephant ear. Generally, I try to avoid plants that require too much maintenance but I am so taken with the size and the exoticism of those plants that I cannot resist. However, the elephant ears must be dug, wrapped in newspaper and put in a cool garage. Come April I will unwrap them, and start them indoors so that by the time the weather warms enough, they will show some growth and can make a visual statement in the garden.

Several years ago, a friend was culling his elephant ears -- Colocaisa esculenta - and offered me one. It was huge and gorgeous and I thought that I would overwinter it indoors so as to enjoy it during the cold weather, but something strange kept happening. I would pass it in the morning and find a puddle on the floor underneath one or another of the leaves. Of course, I initially assumed that I had inadvertently dripped water there when watering. But after several occurrences, it was clear that I could not be that careless so I started investigating. Apparently some plants – including Colocasia esculenta, strawberry, equisetum – exude excess watery sap in a process called guttation first studied by Burgerstein in 1887. It is due to root pressure generated by excess water in the soil.  This was definitely not going to work on wooden floors so I gifted this plant to a friend with tile floors and bought myself some tubers in the spring.

I first became acquainted with elephant ears through displays at various public gardens and they were labeled Colocasias. However, there were very similar plants that are labeled Alocasias. And just to confuse the picture further, there is another similar group called Xanthosomas.

A little digging clarified the situation to some extent. All three of these groups are member of the family Aracea, subdivided further into the subfamily Aroideae. Further, the Colocasia and the Alocasia are member of the Tribe Colocosieae while the Xanthosomas are from the Tribe called Caladieae which is, not surprisingly, the same group that includes caladiums.

I always find the Araceae fascinating. We generally expect seeds to form within petal led flowers or fruit. But the Aracea – otherwise known as   Aroids – bear a flower stalk called a spadix partially wrapped in sheath called a spathe. The Amorphophallus at the New York Botanical Garden that I wrote about previously (http://riverdalepress.com/stories/By-Sura-Jeselsohn,60462?) and that had the local plant aficionados hyperexcited, is also an aroid. I always imagine these plants as benign cobras nestled within the greenery.  Despite never having seen such an inflorescence on my elephant ears, I have found baby plants in unexpected places. 

Whenever, plants are placed into different groups, it is clear that there are substantial botanical differences between them.  So let us look into some obvious differences although I will ignore the issue of differences in flower morphology (http://durablegardening.blogspot.com/2011/01/whats-difference-alocasia-colocasia-and.html).

Colocasia: The heart-shaped leaves tend to droop downward with the stem attaching to the leave, not at the edge (leaf notch), but set somewhat underneath the leaf.  The corm –the swollen base of the stem from which new plants will grow – tends to be rounded. They like full sun and do well in wet soil.

Alocasia: The leaves  - which are frequently shiny and have pointed tips -tend to point upward and the corm is more elongated. They grow best in shade and well-drained soil. The leaves are attached by the petioles at the leaf notch on the edge of the leaf.

Xanthosomas:  The leaves are arrow-shaped (sagittate), with a smooth, waxy upper surface and thick ribs on the lower surface. The leaves also droop downward with the petiole attachment at the leaf notch

Poi - a Hawaiian starchy food staple - is made from an edible taro of the Colocasia family. It pays to mention that most aroids are toxic to humans and it is not readily apparent how to detoxify them or identify edible varieties.

Maybe next year I will look into buying the large and architecturally exciting Alococasia amazonica and expand my repertoire with these plants.

green scene, Sura Jeselsohn

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