What's Blooming Week of July 1? Cecropia-Pumpwood

Cecropia peltata (Urticaceae)
Guarumo, pumpwood (nettle family)
Origin: New World Tropics   
        

One of the most recognizable trees in the South American rainforest, the Cecropia, is a very fast grower, putting on multiple meters of height per year and quickly reaching 15 meters or more. Many species of Cecropia have complex relationships with ants and have been used by humans for a variety of things. The leaves are very large, palmately lobed and covered with silvery-white trichomes on the underside, which makes for a nice view from below. The plants are dioecious and tend not to branch very aggressively. Their stems have a tendency of being very brittle, breaking easily. They are short lived, perhaps sixty to eighty years, and fill a specialized niche in nature.

Nothing lives forever. Not even massive trees in the rainforest. And when a long-lived tree in a forest suddenly dies and comes crashing to the floor, complete chaos ensues in a way that we as humans can hardly imagine. All of the vegetation living underneath the fallen tree is suddenly thrown into full tropical sun. These are plants which need only small amounts of reflective light to survive, and which will burn to death in the full sun. Cecropias, however, love full sun. So when a tree falls, and opens up this new sunny area, cecropias take a foothold and grow rapidly. Within a few years, their large leaf surface is absorbing most of the sunlight, and once again there is shade cast on the forest floor. At this point, the shade-loving understory is free to come back, as well as long-lived trees which need some protection from full sun while saplings. Over the decades, these saplings will grow taller and taller, until they finally replace the original canopy when the cecropias die of old age. After 100 years, the forest looks just as it did before the tree fell.

We call plants like these “pioneer species,” and they are incredibly important. They allow life, which can be very fickle, to move into areas which were previously hostile for one reason or another, by changing the physical environment. Some pioneer species add organic material to otherwise poor soil; others hold water for long periods in areas which are usually dry. Still others, like the Cecropia peltata, take advantage of open conditions and quickly fill them in, reclaiming the space for the jungle. Fallen trees are not the only reason holes open in the rainforest canopy; cecropias can be observed in all kinds of disturbed environments, including roadsides and agricultural clear-cuts.  Marie Selby Botanical Gardens has several Cecropia peltata trees -- one in the Fern Garden and one in the Pre-history Garden, by the Shops, which is currently in fruit.

 

Text by David Troxell