I always thought that the majestic silverswords endemic to Haleakala were related to yuccas or some sort of agave. The photo below is a blooming silversword I took on a trip to Maui back on 2003. Doesn’t it look like a yucca or agave? Especially with that towering stalk of flowers reminiscent of “century plants”. What else could it be?
So a couple of years ago while hiking in Utah, I photographed this blooming yucca below.
I planned to make a farcical Facebook post featuring the above photo going something like this:
Voice: Brah! You from Hawaii!
Me: (Look to my left and see this yucca talking to me.) Yeah, Brah! Wahiawa, my maddah’s side, Kaneohe, on my faddah’s side. What island you from?
Yucca: I not from deah, baht I get cuzins dat leeve on Haleakala! Nevah seen dem fo mee-lee-enz years!
But before I hit Post, I wondered if my assumption about silverswords being a yucca was correct. I’m not sure why I wondered about it. To me it was so obviously related to yuccas that I didn’t think to question it.
It took a bit of trial and error to stumble across the key words: silversword alliance. Most of what I learned about the history of the silver swords are from a few Web pages:
- Silver Sword Alliance – Wayne’s World
- Wikipedia page of the Silversword Alliance
- PBS – Silverswords, Adaptive Radiation
To summarize, the majestic silversword appears to be a descendant of a very humble little plant off the West coast of the U.S. colloquially called a “tar weed”. These tar weeds are in the asteraceae family, along with sunflowers and daises. I’ve read estimates of the first asteraceae immigrant landing in Hawaii as between ten and one million years ago.
But there’s more to the interesting notion of a humble desert plant making a very long journey over an ocean to end up a grand tourist attraction. The silver sword is only one of about thirty descendants of this tar weed immigrant to Hawaii. That is, about thirty very different-looking plants from Kauai all the way to the Big Island.
It’s something that the articles above call adaptive radiation. A single species can relatively quickly evolve to a diverse set of species occupying unique niches. I’m not sure what Hawaii was like a few million years ago, but today climates in the Islands range from tropical beaches, to rain forests, to deserts, to snow-capped mountains, to the high desert climate of Haleakala. That’s a lot of niches to fill.
Coincidentally, on our Oregon Coast trip a few weeks back, we stopped at the John Day Fossil Beds in central Oregon. If you visit the Visitor Center, you’ll see an exhibit on adaptive radiation related to horses. Unless you’re a paleontologist or something, how many times in one day will you think of adaptive radiation?
The fact that many very similar flowers are so profuse in the Southwest Deserts of the U.S. lends to the versatility of this plant. If any plant can be the founder of the species of the Silversword Alliance, it would be the tar weed. All the way from John Day Fossil Beds to the Pacific Shore at Lincoln City, we found many sorts of asteraceae, happy as can be.
I’m not positive if the yellow flower from Southern Utah I photographed below is a “tar weed”. It has the sticky stuff on the green parts, the sunflower-like blossoms, petals that split at the end. Throughout my vacationing around the U.S. Southwest, I’ve noticed dozens of varieties of these plants. I’m at least fairly sure it’s at least related to what I see as “tar weeds” by Googling: tar weed california
Whichever tar weed is the founding ancestor of the Silversword Alliance, it was hardy enough to somehow make a 2000 mile journey and adapt in multiple ways to a place of highly varied in climates.