posted 09/16/14 - I first noticed a handful of these bright yellow shrubs blooming on August 5. I paid particular attention, because I was looking for nectar sources, and it was the only plant blooming besides vinegar weed, isolated spots of CA buckwheat, extremely scattered patches of narow-leaf milkweed, and a tiny tarweed. Hymenoptera seemed to love it with loud buzzy busyness. However, the strangest thing is that in all of August, I never saw a single butterfly nectar on this plant. Not one. It's known to be a good butterfly nectar source, so what gives?
August happened to be when I stopped seeing most butterflies altogether at Pinnacles, except for about 5 spp. (I haven't finished tallying all my notes... ugh!), in contrast to the many species reported on the Pinnacles butterfly list (zoom to 220% to see the light shading) for August from 1999-2011 and mainly observed from the east side. It's unclear the reasons for the stark discrepancy. Certainly, this year's extreme drought (in addition to 2 previous very dry years) comes to mind, but the differences could also be due to observation location (east vs. west) and individual recorder's methods (Paul's trained eye vs. mine, which isn't the best, btw). As a note to me for later, some types of adult butterflies, specifically the coronis fritillary (but there may be others?), spend the extreme heat of the summer hiding in reproductive diapause (pers. comm. Shapiro and Hill), so they wouldn't be out nectaring.
The reason why I bothered to look this plant up today is because a fellow butterfly enthusiast Dave sent me pictures of an unknown plant from his camping trip at Pinnacles (read: east side) last week, on which he said numerous Mormon metalmarks were nectaring (interesting). This post is for him, because I believe his plant photos match my shrubby butterweed from August. I'd like to point out that close-up shots of the flower heads shows much brighter green in color than lower down on the plant with the sagey-silvery colored leaves.