Growing on Ulmus crassifolia. Using 'Keys to Lichens of North America, Revised and Expanded' Irwin Brodo, Yale University Press, 2016. Fruticose key, then Ramalina key... 1) thallus bushy or a pendant tuft from a single point, <6 cm long, 2) soredia present and apothecia rare, 3) soredia white to yellowish green, soralia of various shapes, not wooly, branches usually flattened, 4) branches solid and medulla dense and compact, 5) soralia round, elliptical, or elongate, branch tips tapering, 6) soralia often producing tiny, isidia-like branchlets, branches angular or round in cross section, or flattened in part. Example of isidia-like branchlet in last image. See: http://lichenportal.org/portal/taxa/index.php?taxon=55440