Plant of the week: Streptanthus farnsworthianus

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Flowering S. farnsworthianus

This week’s Plant of the Week is Streptanthus farnsworthianus. Its common name is Farnsworth’s jewelflower, and it is found primarily in the woodlands of the Sierra Nevada foothills. Its flowers are very similar morphologically to the other jewelflowers I have shared recently (which is expected, since flower form is one of the primary characters that has been used in the past to designate taxonomic group, and unlike many other characters that are actually examples of convergent evolution, is comparatively reliable).

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S. farnsworthianus with its first true leaves

This one is particularly interesting because of the dramatic morphological changes its leaves undergo as they get older. As you can see in the images, the first leaves are highly lobed, while the older leaves are entire (“entire” refers to leaves with smooth margins, or edges) and have an almost waxy look. They also turn this beautiful lavender color–usually mustards are purple when they’re stressed, but these ones are supposed to look this way.

Jewelflowers in bloom

I’m trying to concentrate on my studying as much as possible of late, but I couldn’t resist sharing these two beauties that are blooming in my mustard collection.

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This first one is Streptanthus albidus sub. albidus. It’s federally endangered and known only from a few occurrences in Santa Clara County. Commonly, it is known as the Metcalf Canyon jewelflower. Much like many plant species, there is a currently a war waging over the proper classification–it also goes by the taxonomic identity Streptanthus glandulosus sub. albidus. It is found on harsh serpentine soils that other plants are unable to exist on.

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This second species is Streptanthus insignis, also known as the plumed jewelflower. The top flower, which is showier than the other flowers and often sterile, is where it gets its name. It makes its home primarily on serpentine soils in San Benito county.