I think Diane nailed it with Lion's Fairy Tale. I just looked at all of the pics of it on HMF, and many (not all) showed the same unique substance to the petals that I noticed from your pics. Kudos to Diane for her great sleuthing :-D

Could be any of the arid-climate pines? Bristlecone, pinyon (several species), the "Afghan" pines they plant in Las Vegas? Believe it or not, there was a pretty big giant sequoia on the grounds of Utah State University in Salt Lake City when I was there in the 90s. It has to have been watered I would think.

Went down the ROW to check on my weed removal. That stuff is so dense and thick, I took my spot sprayer and a stick so I could move the weeds around so I could spray in between. A lot was dead but too much was partially yellow with green on the inside of the mass. The pump sprayer I used the first time, I thought would get to the insides of the mass because I went over it several times and the sprayer has a strong spray to it but there still was green inside where it looks yellow. Oh well, it rained about and hour and a quarter after I sprayed this second time, and rain safe time was 2 hours but it was so hot and humid, it must have done something. I'll check it in another few days and use the pump sprayer again if I have to. No sign of the box elders sprouting. The worst spot where the plants are at their worst, is a spot where someone in the past has piled lava and miscellaneous decorative rocks, a foot deep, they had removed from somewhere else. So it would be impossible to mow over it. But I think I have it on the run. :-)

Dave, all the eastern Opuntia were originally classified as humifusa. Over time botanists studied Opuntia populations in almost all locations east of the Missisippi. By their own personal observation and by comparing notes with each other they realized that the various populations they had studied were so different from each other that in reality they were actually a complex of several different species that had been all lumped together into a single species. This Opuntia complex has been revised, and humifusa has been broken up into several new species. I have the link for the revision in a comment down below. A lot of people still believe all eastern Opuntia are humifusa, because that old name still exist as a former fact all over the internet. One of the new Opuntia species is called humifusa. I don't remember where it grows. There is no Opuntia humifusa west of the Mississipi. Whoever the original botanist was that classified the western Opuntia species, they never lumped multiple species into a single species.