A banana-aroid fusion?
Imagine my surprise when I discovered a real aroid plant that looked very much like a banana plant! Well, when I first laid eyes on Typhonodorum lindleyanum, I was thoroughly amazed and knew immediately that I had to have one. Turns out that they need to grow with their roots in water, and they do even better if the water they are in is a weak fertilizer solution.
When they bloom, you know they are aroids, as they have a nice large upright spathe and spadix in typical aroid form. The seeds are large and fall into the water, where they germinate while floating. I used to have a large blooming size Typhonodorum, but hurricane Andrew had other plans for it and I ended up losing the plant.
On Aroidia, however, the Banana Aroid, or Musarum, is alive and well, and is the ultimate in aroid-banana fusion. The spadix has the form of a stalk of bananas, while the spathe arches over the stalk, protecting the developing semmules from excessive heat (see picture at upper right). The Banana Aroid also grows with its roots in the water, just as on Earth, but the plant grows much larger by far than any Typhonodorum ever does.
Both banana plants (Musa) and Typhonodorum develop pseudostems to hold the leaves high up. Of course, Musarum is no exception to this. A pseudostem looks like a trunk, but in fact is composed of concentrically overlapping petiole bases with no woody tissue included at all. If you've ever cut down a banana plant, you will have seen this in cross section for yourself. The one time there is any other kind of tissue in the pseudostem is after the plant has produced a stalk of bananas. At that point you will find a fibrous, pithy core that is the extension of the banana stalk running the length of the pseudostem, connecting the bananas to the underground rhizome of the plant.
These bananas are not for eating!
Although the infructescence of Musarum resembles a stalk of bananas, each of the fruits contains two to three slim oblong semmules, while the rest of the fruit is pithy and fibrous. The semmules are quite buoyant and will germinate only in still water pools. The plants produce underground creeping rhizomes that result in the formation of small colonies, similar to banana plants on Earth, but with each new plant emerging at a few feet of distance from the parent. Unlike banana plants, the main stalk does not die off after fruiting because the stalks are produced from axillary buds, not from the terminal growing point.
Typhonodorum lindleyanum is very similar because the main stalks do not die after fruiting, but continue year after year. Typhonodorum does not produce offshoots, however, so colonies are formed by germination of several seeds in proximity rather than from production of basal shoots.
At left is a picture showing a small colony of Musarum in its natural habitat, while at right is a close up view of a Musarum inflorescence. Just as on an aroid spadix on Earth, the part closest to the base of the stalk is the female area and the part towards the end of the stalk is the male portion, with a small sterile appendage at the tip area. The spathe is always positioned over the fruiting structure, acting as a protective hood over the inflorescence and developing fruits. The overall layout closely parallels the actual structure of a banana inflorescence.
Also, in the picture to left, up on the top of the hill, is a large specimen of Cryptophyllum major, as described in a previous article. Habitats with C. major and C. minor are ideal for Musarum because of the hills they produce and the resulting calm lagoons that sometimes form in the midst of them.
Picture credit: LariAnn Garner, Aroidia Research
(Continued in Part IX: Spirals and Floaters)