Bamboo, flowers and famine

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In remote corners of Sichuan Province, China, the arrow bamboo is acting strangely. It grows brown and scraggly with odd grass-like seed heads appearing amidst the foliage. The giant pandas that have traditionally lived on the arrow bamboo forest have stopped eating these plants. The brown-out is spread over a 270,000 square mile area. The Chinese are working hard to help this rare and endangered species survive a botanical disaster. But it happened 60 years ago, and this time it was anticipated. The arrow bamboo flowers only once in 60 years, and the moment it goes into flowering mode the pandas won't eat it any more. This is much like lettuce plants that bolt to flower in the heat, and the formerly delicious leaves turn unpleasantly bitter. Like lettuce, bamboo releases its seed then dies. With bamboo forests, 10 to 20 years is needed for the stand to grow back again from seed.In the 1980s other stands of arrow bamboo in a preserve went to seed and hundreds of pandas died of starvation. But what did the pandas do a century ago or more when the arrow bamboo flowered? Experts say there was more wild land for them to migrate to new stands to feed on. Now, limited to their preserve, the options are gone. Today the Chinese are trying to encourage the old migration paths to reestablish themselves so the pandas will move on to new preserved habitat in search of alternate food.This example of the arrow bamboo illustrates one of the most fascinating facts about this grass-like plant. Few people have ever seen it flower, which makes these plants maddeningly difficult to tell apart. It also wreaks havoc with classification because our binomial system is based on reproductive structures and flowers. After rare bamboos flower there can be a rush to reclassify based on analysis of the blooms.In most cases, the bamboo we grow in our gardens are clones. New plants are made from roots and cuttings of a parent and its parent and so on. This makes them all genetically identical. When a cutting taken in California is sent to South Africa, and another cutting of that plant lands in Australia, each one of these is genetically identical. When the time to flower comes around, every one of these plants, no matter where they are on earth, goes to seed at the same time. This is called "gregarious bamboo flowering" because they all do it simultaneously because they are all technically the very same plant.Bamboo is a wind pollinated flower, so you need a lot of plants together where pollen grains saturate the air. It is believed that there is a very good reason for bamboo to die after it flowers. If you've ever seen a dense bamboo forest in the wild, you'll find the ground riddled with rhizomes seeking an open spot to send up a new clum or shoot. Seed would have little chance of finding an open spot without competition for limited water from the adults. In other words, a seedling would not survive without the old stand dying back to yield open space and moisture to youngsters.In other Third World countries such as India, gregarious bamboo flowering is linked to famine. Rats feed voraciously on the hundreds of thousands of acres of dying bamboo, its seed and flowers. This causes rapid reproduction in the rodent population. Higher numbers of pests then turn to other crops and stored harvests, threatening the human food supply. The bamboo flowering has become a bad omen in India.Though we know bamboo as simply a garden plant, it is far more important to human survival. This single plant touches so many more aspects of modern life from paper making to furniture. Learn more about these amazing giant grasses online at the American Bamboo Society Web site, http://www.americanbamboo.org(Maureen Gilmer is a horticulturist and host of "Weekend Gardening" on DIY Network. Contact her at her Web site www.moplants.com or visit www.diynetwork.com.)