Is this a new type of moss? All the posts I've seen here have referred to: shade and/or acidity and/or poor drainage. We have: no shade, pH 6.8, shale in our soil, with no clay. 13 inches of rain annually (semi-arid). We have cactus in many areas. In addition to growing on soil--this pic shows it thriving on bare rocks on south and southwest aspect, way beyond where any sprinkler ever reaches--it's flourishing in the hottest driest areas of our Okanagan property. Have used everything (shy of Silver Nitrate) to get rid of it.
Looks like a moss to me, possibly a Grimmia based on where it's growing (both substrate and climate) and the sheen from the flash on your camera. From Grimmia in the Bryophyte Flora of North America: (saxicolous = growing or living on rocks) The Okanagan actually has many dryland species of mosses, some of which are becoming increasingly rare as land is used for wineries. The one in your photo, though, is likely something fairly common - anything that grows on or near anthropogenic structures tends to be "weedy".
So Gasterogrimmia it must be. I had been puzzled by comments about dense shade and lack of drainage...yet this grew here in the exact opposite environment. In areas planted to grass, this moss completely takes over where grass has failed to establish a dense cover. Yet there's no evidence of it where grass has always been lush. I find it amazing this moss can persist (indeed thrive) on a boulder that gets so hot from all-day sun that a person could not sit down on it without discomfort. Thank you.
