Most of us who enjoy growing bamboo are aware of two very general types of bamboo: the running bamboos and the clumping bamboos. This is a pretty useful way of categorizing bamboo varieties based on their growth habit. But there is another, higher order of distinction that many gardeners may not know about. That’s the difference between woody bamboo and herbaceous bamboo.
The vast majority of bamboo varieties have hard, woody stems, or culms. This woody composition makes the plants extremely useful for any number of constructive uses. Another tribe of bamboos, known as Olyreae, have soft, tender stems. This makes them less economically important than their woody relatives. Something of a botanical novelty, these herbaceous bamboos grow mostly on the forest floor of tropical jungles in Central and South America, primarily around the Amazon Basin. The tribe of herbaceous bamboo includes 21 distinct genera and more than 100 unique species.
Most of us would not even recognize these modest shrubs as bamboo, lacking the long, elegant poles so characteristic of the great grass. And if you wanted to add an herbaceous Olyreae to your proud collection of bamboo, you’d have a hard time. These unusual specimens are native to a very specific, tropical climate. And what’s more, they are not the kind of plants that most nurseries, even bamboo specialists, have for sale.
But for botanical enthusiasts and real bamboo aficionados, this tribe of herbaceous bamboo is something rather fascinating. Their very existence demonstrates the breathtaking diversity of bamboo and the plant kingdom in general, and sheds some light on the whole system of bamboo classification.
Bamboo classification: Woody and herbaceous
To understand how herbaceous bamboos are related to the woody bamboos that we are more familiar with, it’s necessary to to take a close look at the overall classification of bamboo. The taxonomical hierarchy that we learned in high school gives us 7 different levels (taxa) of organization to be aware of. These include kingdom, phylum, class, order, family, genus and species.
But, like many things we picked up in high school, this system is not the be-all and end-all of biological classification. Botanists and zoologists often insist on intermediate levels like tribes and subfamilies, as well as the higher level of domain and the lower level of subspecies.
Botanists agree that all varieties of bamboo belong in the grass family, Poaceae, with its own subfamily, Bambusoideae. And before we get down to the genus, we divide the bamboo subfamily into three different tribes. Olyreae is the name of the herbaceous tribe of bamboo. And the Olyreae tribe includes 21 genera (plural of genus) of non-woody bamboo.
The two other tribes of Bambusoideae are Bambuseae and Arundinarieae. Bambuseae is the sister group, the closest relatives to the Olyreae tribe, and bamboos of the tribe Arundinarieae are more distant relatives. Arundinarieae are woody temperate bamboos, including many of the most typical and familiar bamboos, despite being more distantly related. The Bambuseae tribe makes up the greatest diversity of tropical bamboos, which are further divided into 2 clades (old world and new world), 11 subtribes, and 73 genera.
The botanical name of the plant comes from the genus and species, for example Bambusa oldhamii. But this binomial name overlooks all the other levels of tribe, clade, subtribe etc. So let’s look at some examples to better clarify the many levels of distinction. Below we can see the complete classification of black bamboo, a popular running variety from China with richly-colored culms; Guadua angustifolia, a giant clumping variety from the tropics of Central and South America; and Cryptochloa strictiflora, an herbaceous bamboo indigenous to southern Mexico and Central America.
Examples of bamboo taxonomy
|Common name||Black bamboo||Giant Guadua|
|Binomial name||Phyllostachys nigra||Guadua angustifolia||Cryptochloa strictiflora|
|Phylum||Angiosperms (flowering)||Angiosperms (flowering)||Angiosperms (flowering)|
|Family||Poaceae (grass)||Poaceae (grass)||Poaceae (grass)|
|Subfamily||Bambusoideae (bamboo)||Bambusoideae (bamboo)||Bambusoideae (bamboo)|
|Tribe||Arundinarieae (temperate, woody)||Bambuseae||Olyreae (herbaceous)|
|Clave||Neotropical (new world)|
|Subtribe||Arundinariinae (the only subtribe)||Guaduinae||Olyrinae|
Running or clumping bamboo
With so many levels of taxonomy, you might expect there to be a hierarchical distinction between the running and clumping bamboo. Surprisingly, there is not. Most of the temperate bamboos (Arundinarieae) are runners, and most of the tropical bamboos (Bambuseae tribe) are clumpers.
But this is not a hard and fast rule. Fargesia, for example is a clumping genus belonging to the Arundinarieae tribe. However, this is one of the only exceptions to the rule.
The rhizomatous nature of herbaceous bamboos can vary. That is to say, some herbaceous bamboos have stronger and more aggressive rhizomes than others, with more of a tendency to take over an area. Research indicates that members of the genus Pariana, for example, can dominate certain areas of the tropical understory. At the same time, some species of Pariana are endanger of extinction due to rapid levels of deforestation in the Amazon. But for the most part, we don’t think of herbaceous bamboo in terms of runners and clumpers.
Distribution of the Olyreae bamboo tribe
The Olyreae tribe consists of three subtribes, 21 genera and 124 species. Among these 124 species,, scholars agree that all but two varieties of herbaceous bamboo are endemic to the neotropics, that is, in the humid jungles and rain forests of Central and South America, as well as islands like Cuba. Buergersiochloa bambusoides grows on the island of New Guinea, and Olyra latifolia has been found in Africa and Madagascar, in addition to tropical America.
As botanists explore and document the astonishing biodiversity of the Amazon, the discovery of new bamboo species is not uncommon. Given the habit of these herbaceous bamboos, in the deepest corners of the rain forest, it’s impossible to know how many more species could be hiding out there in the tropical underbrush. But even as new species are found, tragic deforestation places them in peril.
Based on our current knowledge and systems of classification, we can say that the herbaceous species are not nearly as diverse as the other two tribes of bamboo. Several genera of Olyreae are actually monotypic, meaning that there is only one species in that genus. The subtribe Buergersiochloinae, in fact, has only one genus with just one species, Buergersiochloa bambusoides.
While the herbaceous bamboos are typically short and bushy, Olyra latifolia can grow up to 15 feet tall. Raddiella vanessiae, on the other hand, is probably the smallest bamboo species of all, in the size of both its culms and its leaves. Native to the savannas of French Guiana, it was only first identified about 15 years ago.
To my knowledge, none of the herbaceous bamboo species are available for purchase from your local nursery, or even from a bamboo specialist. If you’d like to see and admire one for yourself, you’ll have to do some traveling. One more reason to take a trip down the Amazon, or over to Madagascar. Don’t forget to pack some mosquito repellant!
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FEATURED PHOTO: Raddia brasiliensis growing in the Amazon underbrush (Wikipedia)