"Recently described" = proposal to distinguish it from J. scopulorum, which it has long been listed under. I posted a link to the paper on a prior occasion.

That's probably where I first saw it. Thanks! I don't know if we would have bothered chasing them down otherwise.

I suspect it might be better treated as a subspecies of J. scopulorum. The differences are decidedly small.

Resin

Quite different in behavior and appearance from Rocky Mountain origin cultivars as seen in cultivation here. I once read it was more similar to J. virginiana than J. scopulorum.

"I once read it was more similar to J. virginiana than J. scopulorum"

That's the claim made for its genetics in the paper by R P Adams where it was first described; however there may be some uncertainty about this, due to incomplete sampling. Morphologically - foliage, cones - it is indistinguishable from J. scopulorum; see J. Duemmel (2009), That New Juniper Species, Douglasia Summer 2009: 10-13. This leaves just the phenology (shorter cone maturation) and climatic adaptation, which are good for making a subspecies.

Duemmel also points out that there are juniper populations in the northeast Olympic Peninsula on Three O'clock Ridge at over 900m altitude and at Deer Park at about 1500m altitude, so the habitat separation from typical J. scopulorum is less marked than Adams suggested at first.

Resin

Reminds me when I was working in Badlands National Park (was National Monument back then), South Dakota. We were not to worry about the ID of the junipers, "they're all hybrids."

Rocky Mountain origin cultivars seen here do not have the same shoot orientation and density as the local native, often fail to produce large, persisting specimens - in fact I am not sure I can name a single one. We do have larger examples of J. virginiana in cultivation here.

"Rocky Mountain origin cultivars seen here do not have the same shoot orientation ..."

Could just be that the cultivars have been selected for their abnormal shoot orientations? Like 'Skyrocket' and 'Tolleson's Blue Weeping'??

"... and density as the local native, often fail to produce large, persisting specimens"

Same applies in Britain, the champion J. virginiana is 21m tall, the champion J. scopulorum is 11m tall. Presumably due to their lack of adaptation to oceanic climates and the good conditions for disease.

Resin

I'm not talking about the crown shape or even the orientation of the main branches. I'm talking about the density of the exterior of the canopy and the drooping of the terminal shoots.

In 2015 Adams published that the populations of "Rocky Mountain juniper" located between the range of seaside juniper and the main distribution of Rocky Mountain juniper are actually intermediate in nature.

http://www.juniperus.org/uploads/2/2/6/3/22639912/341_-_2015_phyto_97155-66adams_scop_marit_dna_rev_12-12-14.pdf