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Gregarious stalked sporangia 2-3.5 mm high. Sporotheca globose 0.9-1.2 mm diameter. Peridium membranous, iridescent with purple, blue, green and golden reflections. Columella reaches approximately the centre of the sporotheca, cylindrical, rounded at apex.
Found on large, bryophyte-covered eucalypt log. Common most years at Birralee.

Roughly 7 generations growing in this spot, all self seeded since I brought three seeds here from the foothills of the Olympic Mountains 15 years ago. Thousands of plants here now. The ground is now covered with pappus hairs from this year’s seeds. As all of these plants are self-seeded it fits the iNaturalist definition of "wild", but I also thought people should know this is not part of a population that has persisted here since before European contact.

(Update 3/24 these thistles are no longer so dense here, but are still numerous.)

This species was on a list I found 21 years ago of those native species that hadn’t been recorded in Seattle in decades when I started studying how to identify them all, and just what habitats they naturally grew in, and looking for where I could find wild seed of the species on that list from sites physically and ecologically close to Seattle, to try planting in the most promising spots here.

I started with the goal of helping the recovery of butterfly species that had become rare in, or had disappeared from, Seattle, and knew thistles to be important as both butterfly nectar, and host (caterpillar food) plants, and had learned that all 4 of Seattle's native thistle species were on that list of our lost species. So I am pleased to see a bit of improved butterfly habitat in this spot where this native thistle species is thriving again!

I’ve since spent 15 years weeding this site and controlling the Artichoke Plume Moths https://www.inaturalist.org/taxa/319034-Platyptilia-carduidactylus, the best I can, as the mother plants sent their offspring to occupy the growing patch of land vacated by my weeding around them. I also have a significant problem with non-viable seed, more later in the season, than with the initial crop, which I believe is due to predation of the receptacles, where the seeds develop, by the introduced Rhinocyllus conicus - the Nodding Thistle Receptacle Weevil https://www.inaturalist.org/taxa/229899-Rhinocyllus-conicus .