The Curious Case of Hawaii's Endemic Orchids

Orchids and Hawai'i are nearly synonymous. It may come as a surprise then to learn that only three species of orchid are native to this lush archipelago. In fact, there are more non-native species of orchids growing in Hawai'i than there are native. Like much of Hawai'i's endemic flora and fauna, these three distantly related orchid species find themselves on the brink of extinction. How and why only three species of orchid came to call Hawai'i home is a great mystery and it is one that conservationists are struggling to understand before it is too late. 

Orchids produce the smallest seeds of any plants. These dust-like propagules can travel far and wide on the slightest breeze. If any plants were to make it to one of the worlds most remote island chains my bet would be on the orchids. Alas, until settlers arrived, Hawai'i was home to only three - the Hawaiian bog orchid (Platanthera holochila), the Hawai'i jewel-orchid (Anoectochilus sandvicensis), and the Hawai'i widelip orchid (Liparis hawaiensis). The ancestors of these plants must have traveled quite a distance to get to these islands. The Hawaiian bog orchid, for instance, can trace its ancestry back to a related species of Platanthera native to the Aleutian Islands whereas the other two likely blew in from Asia. 

These three species were once found in a variety of locations. Today, however, all of that has changed. Populations of each of Hawai'i's endemic orchids are declining at a rapid rate. In fact, the Hawaiian bog orchid is considered one of the most endangered orchids in the world. The causes of their decline is what one would expect from an island species - habitat destruction, the introduction and subsequent spread of invasive species, and just poor land management in general. It is strange though that so many orchid species from elsewhere in the world are thriving as their endemic cousins are declining. 

Though the exact reasons for this remain uncertain, some of it has to do with another invader - honeybees. Honeybees are native to Europe and are generalists in their foraging abilities. Until bees were were brought to Hawai'i, many introduced orchid species behaved themselves. There simply wasn't anything around to pollinate them. Once honeybees came onto the scene, a few of these introduced species such as the bamboo orchid (Arundina graminifolia) were suddenly able to reproduce. The tropical climate made the land ripe for the taking. But this is only part of the picture. There is another, more interesting conundrum that remains to be solved. 

Orchids absolutely require mycorrhizal fungi to germinate and grow. Why is it then that introduced orchids seem to be doing so much better than the Hawaiian endemics? Good question. Some orchids can be very specific about the fungi they will partner with whereas others are not. It could be that all of the introduced orchids that are naturalizing are generalists whereas the endemics are specialists. It could also be that the endemics simply can't handle the altered disturbance regimes brought on by modern society.

The real reason is probably some combination of these and many more but the fact of the matter remains, Hawai'i's native orchids are in trouble. Since they are not nearly as showy as other orchids they are rather overlooked. This is a shame because if they are lost from their native range, they are gone from the world forever. Luckily there are people out there like Dr. Nicole Hynson of the University of Hawai'i and Dr. Larry Zettler of Illinois College who are working to understand, propagate, and conserve these unique species. 

Photo Credits: University of Hawai'i Museum (http://bit.ly/1K8pjKC), Arkive (http://bit.ly/20kxg17), and G. Daida (http://bit.ly/1K8phCw

Further Reading:
http://bit.ly/1PKOV0C

http://s.si.edu/1QRn0el

http://s.si.edu/1Rjwd1g

http://s.si.edu/1W8bGMb

http://www2.hawaii.edu/~nhynson/Hynson_Lab/Welcome.html

http://www.ic.edu/LarryZettler