monkeyflower spectrum

Yesterday I went out to Crestridge Ecological Preserve, about a half hour’s drive from coastal San Diego. There will be lots of photos from the trip, but here’s a little panorama to get started, featuring the common sticky monkeyflower, Mimusus aurantiacus.

Around here you can easily find clones of it that are soft apricot-yellow, or ones that are orange, or scarlet. I’d read somewhere that pretty much all the forms west of Interstate 15 were scarlet, and all of those east of it were apricot. It was supposed to have something to do with coastal plants supposedly being pollinated by hummingbirds, while those inland were visited by bees. (EDIT, May 9: Another source I just looked at mentioned that the primary pollinator of the pale form was the hawk moth, which makes sense for an adaptation towards larger, paler flowers.)

Well, what do you make of this? The top composite shows the plants, below are the details of the flowers on the plants. (You’ll definitely have to click to enlarge this photo to make sense of this wide panorama.) On this north slope were five plants that showed the complete range from apricot to scarlet, and the plants were arranged sequentially as if they lines in a spectrum. Crestridge is a couple dozen miles east of I-15, so I think these plants blow the I-15 hypothesis out of the water.

I’d guess the real answer will implicate plant-sex and require a more nuanced understanding of how these different color forms establish themselves in different areas.

7 thoughts on “monkeyflower spectrum”

  1. So interesting. We get only one color here on the Central Coast – the basic orangy yellow. I’ll have to look closer to see if there are any slight variations! You’re lucky to be able to see all these different colors. I look forward to a follow up post one of these days if you find out more info about the cause of the variation.

  2. A cursory search on Google brings up article with titles like “Altered trans-regulatory control of gene expression in multiple anthocyanin genes contributes to adaptive flower color evolution in Mimulus aurantiacus”.
    This serious subject, apparently, and may be interesting, but what I find delightful is you finding (and noticing) all these colors all in one place. I want to go sit there for awhile and enjoy!

  3. I’ve seen both scarlett and apricot forms west of I-15, around San Elijo Lagoon and Penasquitos Canyon.

  4. I’m not far from Country Mouse, so I’ve only seen the native yellowish apricot colored form here, and at least on this property the color seems stable from plant to plant. I didn’t realize there was so much natural variation (I presumed some was a result of commercial hybridization) but I’m really surprised to see so many variants in the same place! Fascinating!

  5. CM, my neighborhood’s standard monkeyflower color is scarlet, with almost no variations, so it’s a treat for me to see the other variants. I’ve started to do more research and it definitely sound like at least one more post.

    Sue, thanks for pointing out the literature on this plant. I was a ware of a couple treatments, but I found way more than that today. It looks like there’s been an explosion in monkeyflower research in the last five years. And yes, it’s a cool plant all on its own.

    Travis, I haven’t been up to San Elijo enough to see the variation up there, but I’ve noticed some different forms in Penasquitos Canyon. The notion of Interstate 15 as a divider is definitely an oversimplification!

    Brent, thanks! I love it when cool plants do cool things…

    Curbstone Valley, the foothill populations around here seem fairly uniform and probably look a lot like your typical form. In addition to the pale color, the flowers are also substantially larger than the red form. I don’t think it’s because they get several times the water of their coastal relatives, and it might favor night pollination by moths.

  6. What a lovely range of colours – however they come about! I naively thought that some species just naturally had a range of flower colour, like those seed mixes you buy – we get colour themed packets of Californian Poppies all the time. I’m feeling a bit confused, so shall go back to just enjoying the differnt shades.

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