North America's Native Bamboos

I would like to introduce you to North America's native bamboos. There are three species, all hailing from the same genus - Arundinaria. Today they hardly get the attention they deserve but in the past, there were an incredibly important group of plants both ecologically and culturally. Today they occupy a mere shadow of this former glory so in keeping with the goal of In Defense of Plants, I am here to defend these plants. 

There are three species in the genus Arundinaria -- A. appalachiana, A. gigantea, and A. tecta -- and all of these are native to the southeast. There has been a whole lot of taxonomic debate over these plants ever since Thomas Walter first described the first of them in 1788. Since then, there have been many revisions. Whether or not any Asian bamboos belong in this genus is a story for another time but recent genetic work confirms that these three species are valid. 

Each differs slightly in its ecology. Giant or river cane (A. gigantea) is a denizen of alluvial forests and swamps as is switch cane (A. tecta), although switch cane seems to be a bit more obligate in its need for swamp-like habitats. Hill cane (A. appalachiana) was only described in 2006 and prefers dry to moist forested slopes and forest edges. One interesting things about hill cane is that it drops its leaves in the fall, an unusual trait for a bamboo. 

A majority of their reproduction is asexual via spreading rhizomes. All three species of cane rarely flower. When they do, plants usually die after setting seed. As such, a majority of canes you may encounter in the wild are clones connected by a vast network of large rhizomes. These rhizomes can persist for decades or even centuries meaning persistent patches are quite old. These rhizomes can lay dormant for some time as well, waiting for some form of canopy clearing disturbance to provide the conditions they need to grow again. 

Despite how common these canes may seem in some areas, they are nowhere near what they once were. European settlers wrote of vast stretches of rivers and swamps completely covered in cane. They called these "canebrakes" and they persisted as such due to the importance of Arundinaria to Native Americans. Regular burning created perfect conditions for cane to thrive and thrive it did. 

Because it was once so prolific, its ecological impacts were quite immense. Many animals relied on canebrakes for food, shelter, and a place to breed. Unfortunately, cane was also highly sought after as food for cattle. Unsustainable grazing took its toll, as did fire suppression. What's more, the rich soils and relatively flat topography in which these canes tend to grow was also the preferred spot for farming. In fact, settlers used canebrakes as an indicator of good soils. Vast acres of cane were cleared and plowed under. Unfortunately for cane and the habitat it created, when it disappeared, so did much of its function.

Once cleared, cane is slow to return. Its tendency to not flower frequently means few seeds are ever produced. Even clonal reproduction can be tedious if the right conditions are not present. Cane has lost most of the ground in which it once grew. With it went vital components of the southeastern ecosystem. It has even been suggested that the loss of canebrakes played a major role in the extinction of Bachman's warbler (Vermivora bachmanii) though it is hard to say for sure. 

Though all three species of cane still persist today, they are not the ecosystem builders they once were. It will take a lot of changes here in North America both ecologically and culturally before these three bamboos can ever regain much of their former range. Still, they are interesting plants to encounter and well worth taking some time to enjoy. 

Photo Credits: [1] [2]

Further Reading: [1] [2] [3] [4] [5]

1,730 New Plant Species Were Described in 2016

Manihot debilis

Manihot debilis

The discovery of a new animal species is celebrated the world over. At the same time, plants are lucky to ever make headlines. This is a shame considering that plants form the backbone of all terrestrial ecosystems. The conversation is starting to change, however, as more and more people are waking up to the fact that plants are fascinating organisms in their own right. In a recent addition of Kew Garden's State of the World's Plants, they report on 1,730 newly described plant species from all over the world.

Begonia rubrobracteolata

The discovery of these new plants species is truly a global event. Central and South America, Africa, tropical Asia, and Madagascar saw the addition of many intriguing taxonomic novelties. For instance, Malaysia can now add 29 new species of Begonia to their flora. Africa can now boast to be the home of the largest species of Bougainvillea in the world. Standing at 3 meters in height, it is an impressive sight to behold. Madagascar was particularly fruitful (pun intended), adding 150 new species, subspecies, and varieties of Croton all thanks to the diligent work of the late Alan Radcliffe-Smith. 

Commicarpus macrothamnum  Photo Credit: Ib Friis

Commicarpus macrothamnum Photo Credit: Ib Friis

One of the most exciting finds from Madagascar was a new genus of climbing bamboos named Sokinochloa. So far only 7 species have been named. The key to unlocking the diversity of this new genus lies in their flowers, which are not produced on a regular basis. Like many bamboos, the Sokinochloa produce flowers at intervals of 10 to 50+ years. The new discoveries did not consist entirely of small understory herbs either. Some of those 1,730 plants were massive forest trees.

Sokinochloa australis

Sokinochloa australis

One of these new tree species is Africa's first endemic species of Calophyllum (Calophyllaceae). They were discovered during a survey for a uranium mine and, with fewer than 10 mature individuals, are considered critically endangered. Expeditions in Central America and the Andes turned up 27 new tree species in the genus Sloanea (Elaeocarpaceae) as well as 10 new species Trichilia, a genus of trees belonging to the mahogany family (Meliaceae).

The list could go on and on. Even more exiting is the fact that 2016 wasn't a particularly exceptional year for new plant discoveries. An estimated 2,000 new plant species are discovered on an annual basis. We aren't even close to grasping the full extent of plant diversity on this planet. What plants desperately need, however, is more attention. More attention leads to more scrutiny, more scrutiny leads to better understanding, and better understanding leads to improved conservation efforts. We could be doing a lot better with conservation efforts if we considered the plants whose very existence is essential for all life as we know it.

Barleria mirabilis  Photo Credit :  Quentin Luke

Barleria mirabilis Photo Credit: Quentin Luke

Tibouchina rosanae  Photo Credit: W Milliken

Tibouchina rosanae Photo Credit: W Milliken

Englerophytum paludosum  Photo Credit: Xander van der Burgt

Englerophytum paludosum Photo Credit: Xander van der Burgt

You can download your own copy of the State of the World's Plants by clicking here

All photos thanks to the Royal Botanical Gardens at Kew unless otherwise noted.

Plight of the Panda: a bamboo story

There are few creatures more iconic than the giant panda. These bears are the poster children for conservation movements around the world. Unlike their ursine relatives, pandas have abandoned carnivory for a diet that consists almost entirely of bamboo. In the light of human destruction, specialist lifestyles like the pandas are a risky strategy. It doesn't take much to upset such obligate relationships and humans are quite proficient at doing just that. However, the plight of the giant panda has just as much to do with the ecology of its food source as it does man-made destruction of its habitat.

Essentially giant grasses, the bamboo tribe consists of over 1,400 species worldwide. Not only are bamboo some of the tallest grasses in the world, they are also some of the fastest growing plants. Some have been known to grow 250 cm (90 in) in only 24 hours! As typical with grasses, bamboo can reproduce via underground rhizomes, forming dense stands of clones. Entire forests can be made up of the clones of only a few individuals.

The strangest part of bamboo ecology is that they rarely flower. A typical bamboo will live for 20 to 60 years before flowering, with some species taking well over 100 years. As such, bamboo experiences mast flowering events, with entire bamboo forests flowering all at once. After flowering and setting seed, the bamboo dies. Entire bamboo forests are lost in only a matter of weeks.

There have been many hypotheses put forth to explain this and while each has likely played a role in the evolution of this strategy, these mast flowering and subsequent death of bamboo forests probably serve to ensure the survival of the next generation. If the adults were to live through flowering and seed set, it is likely that the thick canopy of the parents would be too much for young seedlings to overcome. What's more, mass die offs create a significant fuel load for fires to sweep through. However catastrophic a fire may be, it reduces competition for bamboo seedlings.

Before humans fragmented their habitat, giant pandas had no trouble dealing with mass bamboo die offs. They simply migrated to a new bamboo forest. Anymore today, they cannot do that. When a bamboo forest flowers and dies, pandas in that area have nowhere to go. They simply starve to death. Because of this, pandas now occupy a mere fraction of their former range. What intact bamboo forests remain are restricted to the highlands of the Sichuan, Shaanxi, and Gansu provinces.

Despite considerable success in the captive breeding of pandas, there is simply not enough habitat to support their recovery in the wild. Because of this, captive breeding programs have come under harsh criticism. It has been argued that the massive amounts of money spent on captive breeding of pandas could be spent on habitat conservation projects elsewhere. No matter where you stand on the subject, there is no denying that pandas fall under the charismatic megafauna syndrome. They captivate the hearts and minds of people all over the globe. They also encourage the masses to open up their wallets. Sadly, it is probably too late giant pandas in the wild. If anything else, they certainly serve as a stark reminder of the importance of habitat conservation on a large scale.

Photo Credit: Abby Wood, Smithsonian's National Zoo (http://bit.ly/1qDX21K) and Daniel J. Layton (Wikimedia Commons)

Further Reading:

http://www.jstor.org/stable/10.1086/303243?seq=1#page_scan_tab_contents

http://www.completebamboo.com/bamboo_behaviors.html