Home & Garden Columns

Green Neighbors: When Is a Tree Not a Tree? When It’s a Great Big Grass

By Ron Sullivan
Tuesday November 13, 2007

Bamboo is a plant with many faces and many reputations. It’s invasive, except when it’s not; it’s edible, tough, fast-growing. It’s good for scaffolding, houses, roofs, containers (in sizes from spice-bottle to bazooka), musical instruments (the Malagasy valiha tubular harp and sodinha flute, just for example), bows and arrows and the bowstrings too, fishing rods, curtain rods, flooring, paneling, dishes, kitchen and table utensils as well as the table and most of the kitchen itself, including water pipes.  

So you can eat bamboo shoots using bamboo chopsticks (or a bamboo knife, fork, and spoon) from a bamboo plate and wash it down with a drink from a bamboo cup, poured from a bamboo pitcher, sitting on a bamboo chair at a bamboo table on a bamboo floor in a bamboo house in a bamboo forest, listening to a bamboo orchestra. You can spill it on your bamboo-fiber shirt if you don’t watch out. 

I’ve even seen a bicycle made mostly of bamboo, and a mo-ped veneered in it. I’ve never heard of bamboo booze but I figure it’s only a matter of time.  

Don’t sing “Under the Bamboo Tree” as you wobble down the road, though, or some pedantic individual like me might yell out to correct you. Even timber bamboo is just tall grass. That’s part of the secret of its biological success and its indispensability to us. 

Grass has the physiological advantage of fast growth from advancing roots. That’s why prairies get along just fine while being grazed by bison; or savannas, ditto with wildebeest and other antelopes, zebras, and whatever else still ranges across Africa in magnificent herds. Grass doesn’t mind being bitten off at the top. That pruning doesn’t affect its growth pattern the way it would that of trees or most normal herbs.  

There’s a sort of running joke among evolutionary botanists about the war between the grasses and the trees, for world domination. (Currently, the grasses have domesticated us for their purposes much more successfully than the trees have: Consider how much more of the land’s surface we’ve devoted to grains—grasses—than to fruit orchards and ornamental trees.) It seems to me that the various bamboo species represent a sort of biological compromise between the two, or maybe a subversion of the tree strategy of size and structural sturdiness.  

Bamboo accomplishes this by having a critical proportion of lignin and cellulose in its tissues—lignin for stability, cellulose for tensile strength—and a tubular stem/trunk structure for optimum light weight to be supported.  

Another of bamboo’s physiological peculiarities is the way it flowers.  

Yes, grasses flower, if someone doesn’t mow or graze them. They’re wind-pollinated; the flowers get away with being inconspicuous since they don’t have to attract pollinators. Any bamboo species tends to bloom rarely—30 to 80 years, by some estimates—and then all at the same time.  

And then the plants die. The synchronous bloom and seed-setting is followed by the withering of the parent plant. Since a whole grove or even forest might consist of one clone arising from a central root mass, rather like an aspen clone, it all follows the same sequence and then drops dead.  

This has interesting consequences. It might be that it’s not such a problem as had been supposed for pandas, who feed exclusively on bamboo foliage, unpromising though that is. They’ve survived rather a lot of these bloom years; I guess that’s no surprise. What they need, apparently, is more bamboo forests to move to when their heretofore reliable green buffet disappears.  

The mass flowering of bamboo is reminiscent to the life cycle of those cicadas that live underground for 17 years, then stage a mass emergence, mate, and die. (Or 13 years, depending on the cicada.) Oaks and other nut trees do something similar on a less dramatic scale when they bear heavily and en masse in their masting years.  

It’s all about predator satiation. The bamboos flood the market to ensure that some seeds don’t get eaten, and do it on such a long cycle that seed-eaters are unlikely to adapt their own life cycles to it.  

“If bamboos flowered every year, seed eaters would track the cycle and present their own abundant young with the annual bounty,” wrote Stephen Jay Gould. “But if the period between episodes of flowering far exceeds the life-span of any predator, then the cycle cannot be tracked (except by one peculiar primate that records its own history).” 

Gould notes that such a reproductive cycle, in this case so long that any seed-eater would starve to death waiting before becoming dependent on it, works just fine evolutionarily: “It is sometimes advantageous to put all your eggs in one basket—but be sure to make enough of them, and don’t do it too often.” 



Photograph by Ron Sullivan. 

A timber bamboo in a Berkeley backyard.