All too often, botanizing is restricted to the land. Sure, there is the occasional foray to a marsh or bog but, for the most part, we plant folk rarely get wet in our quests to meet new and exciting plant species. There is an entire world of underwater plants that don't get enough credit. One such plant is Aponogeton madagascariensis, the lace plant.
Anyone into planted aquariums has undoubtedly come across this species at least once. It is kind of a holy grail of aquarium gardening. Hailing from Madagascar, this is one of the truly aquatic Aponogeton species. While there are a few different geographic variations, they all are easily recognized by the lacy appearance of their leaves. Known as "fenestration" the lacy structure is the result of programed cell death during the development of the leaves. What is the function of the fenestration?
There have been many hypotheses. Some believe it helps to reduce damage from turbulence while others believe it helps to increase movement around the leaves to avoid stagnation. The truth is, no one is entirely certain. However, a clue to the benefits of fenestration has come out of work done on an entirely unrelated terrestrial plant species. The epiphytic arum commonly referred to as a Swiss cheese plant also has fenestrated leaves. Researchers at Indiana University in Bloomington have found that, almost counterintuitively, the holes in the leaves may help gather more light in a shaded environment. The understory of a rainforest and the underwater habitat in which the lace plant grows may be more similar in light availability than you would think. How would holes in the leaves allow the plant to gather more light?
As it turns out, a fenestrated leaf with the same surface area as an unfenestrated leaf can grow bigger. By spreading out its surface area over a larger region, a fenestrated leaf is actually more efficient at gathering what limited light is available. More work needs to be done to see if this is truly the case for the lace plant but the idea is tantalizing to say the least. Sadly, like too much of Madagascar's wildlife, the lace plant is becoming quite rare in the wild due to habitat destruction.