Thank you to newsflash66@UBC Botanical Garden Forums for sharing this image via the adaptive radiation. The modern day species of the silversword alliance include members of the genera Argyroxiphium, Wilkesia and Dubautia, and these species occur in the habits of cushions, mat-forming perennials, shrubs, trees and climbing woody vines. Species in the alliance can be found in dry sites (less than 25cm of precipitation per year) to the purported “wettest spot on Earth”, where precipitation can exceed 1000cm in a year. Furthermore, they are found at almost all elevations in the Hawaiian islands, from 75m above to 3750m (see ecological and physical adaptations of the silversword alliance for more).
The question may have arisen in your mind as to how it is known that these plants evolved from an ancestral California tarweed. There are several ways to verify this. The strategy in most cases today would be to determine the relationships of the species by comparing the number of changes in certain molecules. This was done in this case (and it indeed bolstered these facts), but a more traditional method was also used. Artificial hybridization experiments between modern-day Californian tarweed species and members of the silversword alliance were undertaken, with the idea being that if the species could successfully cross, more evidence would be added to the pile (and again, yes, this is the case). More than incidentally, the hybridization experiments also help make inferences as to how this rapid evolution took place, suggesting mechanisms such as autopolyploidy and allopolyploidy (i.e., chromosome doubling within a cross of a single species or a cross between two species).
I've already referenced this site a few times, but here's the main page: read Adaptive Radiation and Hybridization in the Hawaiian Silversword Alliance by Dr. Gerald Carr for more on the science behind the silversword alliance, including this page specifically on today's species, Argyroxiphium sandwicense subsp. sandwicense, or Mauna Kea silversword. To read more about the genus, visit Wikipedia's page on Argyroxiphium.
Beautiful picture. And of course the species name sandwicense gives a clue as to where it is from, being a reference to the Sandwich Islands, which is what Captain Cook called the Hawaiian Islands. I also refer you to the article by Wayne Armstrong called The Silver Sword Alliance at http://waynesword.palomar.edu/ww0903b.htm .
Oh, gosh, Daniel.. so many times I wish someone would tell us the size some of these flowers are... and the mosses and other fungi. They are so beautiful, and if they are small, one could just pass many of them by without seeing them. I used to pick miniature boquets for my desk at work.. one flower I particularly liked was a tiny 5 petaled blue flower with a yellow center, but the whole plant was about an inch high and the flower was less than 1/2 inch across.
I loved the tiny boquets, though, and put them in shot glasses, just the right size for little flowers but didn't take up a lot of room. Another blossom I used were clovers.
Just wishing for more information on size.
Thanks for the lovely pictures anyway.. opening up a whole new world of nature for me.
That's a fair comment, Sue. I suppose the way I try to work around that is by providing links to more photographs that give scale.
Or else place a ruler or a penny or a hammer or a cm stick beside the plant. Any object that would immediately give a scale. Or an insect or a bird or a pet or a human depending on scale.
Right, but a lot of people freely share their photographs and I'm not going to impose that as a condition. I'm pleased enough when the plant is identified and it's something that hasn't been featured before.
this is a fine picture-----the links give you
give one photos of the size in relation ship
to a human---it is quite large when mature---
looks like my hair first thing on a humid day---
daniel are you aware that tropiflora in my part of
florida and they have web site ----
will be selling just about all its plants for
new public gardens in singapore-- perhaps you
could go some day.
When you mention the incredible variation in habitat precipitation and elevation, it makes me wonder. Did some of the first rainy-habitat colonizers happen to be epiphytic or epilithic?(did i just make that word up?) I find it hard to imagine that a plant thats adapted to arid environments, descended from plants adapted to arid environments, would end up doing just fine in the "wettest place on earth" unless they took up some sort of alternative lifestyle that imitated a semi-arid environment, like the trick that cactuses pull in the american tropics. But it seems like it didn't take very long to figure out that trees and lianas were pretty good ideas too. Either way, I'm totally amazed by adaptive radiation.
That Tropiflora story is pretty amazing, Elizabeth. Yet another place to visit one day (I suppose it'll be Singapore, because I doubt I'll have a chance to visit Florida before it is all sold).
Joe, you're right, that is pretty curious. It's the cushion-forming Dubautia waialealae that lives in the wettest spot. I usually associate cushions with high alpine areas and deserts. I wonder if it's able to survive in that area despite the rainfall because of the volcanic soil, which presumably is extremely well-draining. That doesn't explain why the cushion-forming strategy was used in its evolution, though - but I'm sorry, I don't know enough about that species to hazard a guess.
Regarding scale and size, my grandfather took many slides (remember those?) of flowers and plants. He kept an acorn in his camera bag to place somewhere near the subject.
Wow, thanks for all the advice everyone.. and Jim Service.. your grandad had an excellent idea.. nothing like scale to help give a size.. will check out the reference site now.
thanks
Sue,
Your little five petaled blue flower with the yellow center sounds like Sisyrinchium sp. (Iridaceae).
Sorry, I was mistaken. Sisyrinchium sp. have six petals. See Botany Photo of the Day June 15, 2006.