Friday, August 28, 2009


Krameria ixine

When I first saw this shrub in Guanica, I was struck with how beautiful it was; I had no idea how interesting the ecology would turn out to be.

I love the unusual color of these flowers. It is a rich maroonish-pink, with a silvery sheen that gives the flowers a velvety appearance. That silver sheen continues onto the vegetation.

Upon closer investigation of the floral structure, I saw these three petaloid appendages, which I first took to be modified anthers (I had foolishly left my hand lens at home and did not have a microscope available with me at this stage of the trip. These things make a big difference). I really did not have a clue as to what family this plant belonged in. Those of you familiar with the flora of the western US, may recognize some of the characteristics of this plant, as there are Krameria sp. throughout the western US.

It turns out that Krameria is the only genus in the family Krameriaceae, and there are only apporximately 19 - 25 species in that genus. So not a family you learn in a botany class in Missouri.

What about the cool ecology? Two things have peaked my interest.
(1) These plants are hemiparasitic.
(2) Those petaloid structures aren't modified anthers, but modified petals that are called elaiophores. Elaiophores contain oil-secreting glands that produce oil as rewards for pollinators. (I just found all of this out yesterday, and I am pretty jazzed about it). I haven't found out much yet, like - what are the bees using the oil for. Other species of are pollinated by Centris bees. I found one vague reference to these bees using the oil to provision their nests. Are any of our resident bee experts familiar with this genus of bees?


Sparkling Squirrel said...

Way cool. What are the bees doing with the oil? Crazy.

Erin said...

Maybe they are moisturizing...

Molly said...

Centris bees are really beautiful, furry and large. I just looked in Mich's tome and he mentions that bees of that tribe (Centridini) are known to collect oils from Malpighiaceae, Krameriaceae, or Calceolaria (Scrophulariaceae), "presumably for use in provisioning cells" (i.e., the developing larvae eat the oils along with pollen and/or nectar). It sounds like the bees also use the oils to help waterproof their nests, which are often in the ground. "Cells of Epicharis zonata" (also a centridine) "in French Guiana were so well waterproofed that immature stages survived in sand that was well below the water table for months during the wet season."
Some review papers for the nesting habits of Centris: Coville, Frankie, and Vinson (1983) and Frankie et al., (1993)

Jenny said...

What a cool plant! Your photos are lovely.
You might also take a look at:
Buchmann, S.L. 1987. The ecology of oil flowers and their bees. Annual Review of Ecology and Systematics 18: 343-369.