Brother of Hibiscus

Islands are known for their interesting flora and fauna. Until humans came on the scene, colonization events by different species on different islands were probably rare events, with long stretches of time in between. Because of this, islands are interesting experiments in evolution, often having endemic species found nowhere else in the world. Hawai'i was once home to many different kinds of endemic species. One such group are the Hibiscadelphus.

As you may have gathered by the name, Hibiscadelphus is a relative of hibiscus. The Latin name means "brother of Hibiscus." Unlike the widely splayed flowers of their relatives, Hibiscadelphus flowers never fully open. Instead, they form a tubular structure with a curved lower lip. The genus consists of 7 species. Four of these have gone completely extinct, two are only maintained in cultivation, and the remainder is barely holding on. There have been attempts to reestablish some species into other portions of their range but due to hybridization, these attempts were ceased. In my opinion this is a shame. In this case, a hybrid is better than losing both parental species and it would still be uniquely Hawaiian.

Why are Hibiscadelphus so rare? Well, humans have a sad history when it comes to colonizing islands. They bring with them a multitude of invasive species at a rate in which the local flora and fauna cannot adapt. They change the land through cultivation and development as well as by subduing natural fire regimes. Also, they wipe out keystone species, which causes a ripple effect throughout the environment. Hibiscadelphus have faced all of these threats and more. Pigs and rats eat their seeds, their habitats have been turned over for the ever-increasing human population, fires have been stopped, and some of their pollinators, the endemic honeycreepers, have also been driven to extinction thanks to avian pox and malaria. Sadly, this is a story that repeats itself time and time again all over the world. For now, the future of Hibiscadelphus is rather bleak.

Photo Credit: David Eickhoff

Further Reading:

http://bit.ly/2ao84X1

http://bit.ly/2aEfpkn

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