The Biologist Is In: Botanizing in Alaska: Yellow Paintbrush

Tuesday, August 11, 2015

Botanizing in Alaska: Yellow Paintbrush

I found this plant growing up at the top of a mountain, where we were starting a four-wheeler trip from. I recognized it as a paintbrush flower (genus Castilleja), though I had never before seen one this pale. The genus contains some 200 species that are often difficult to distinguish. The populations of various species grade into each other, with intermediate forms confusing identification even further.

There are three Castilleja species noted as living in Alaska: "Yellow Paintbrush" (C. unalaschensis), "Mountain Paintbrush" (C. parviflora), and "Scarlet Paintbrush" (C. miniata). C. parviflora and C. miniata are generally found in shades of red or pink, so I'm pretty sure I found an example of C. unalaschensis. The "Yellow Paintbrush" grows through much of southern Alaska, where it is typically seen in shades of yellow to pale orange. It seems to be closer to white around Fairbanks, however.

Paintbrush flowers, in all their shades, are lovely wildflowers. The most interesting thing about them to me, however, is that they're parasites. They have specialized roots called haustoria that grow into the roots of other plants to steal moisture and nutrients from the victimized plant. They're not a seriously aggressive parasite and could theoretically live on their own, but they definitely get a boost by feeding off a neighbor (who does suffer from the process). This Paintbrush could have been feeding on all the other plants visible in the photo, as they don't specialize on one type of plant.

I reached out to a Castilleja specialist hoping to get some better idea of the identification for the plant I found. I was surprised at how quickly he responded with very useful information.

Hi Darren,

You mentioned in your blog that there are three Castilleja species in AK, but that is not correct. Besides the three you listed, there are C. pallida, C. elegans. C. raupii, C. chrymactis, and C. hyperborea. Your plant is either C. unalaschensis or C. pallida (also known as C. caudata in some Alaska references). It matches C. unalaschensis (which is usually yellowish) in the somewhat compact inflorescence, but the color is closer to that of C. pallida. It's definitely one of those two, but I can't offer a definitive without more photos, particularly close up ones. If I had to choose, I'd call it an unusually pale form of C. unalaschensis.

Best wishes,

Mark

His response highlights the need to take excellent photos for identification purposes. It helps to know what the key parts of the plant to photograph are in advance as well. I didn't even recognize this plant as a Paintbrush until I was reviewing my photos, well after the trip was over. Next time I promise to get better and more-informed photographs.

Thanks again, Mark!

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