The Xerophyllum tenax which is in the garden I manage was introduced to our cultivation in 1974. It persists, but not surprisingly doesn't flower every year. (I think it was now 3 summers since I recall seeing two flower stalks) The soil surrounding the plants is gravelly and lean, and its aspect is on a west-facing 30 degree slope. Our summers are dry-ish during July and August. At that time, some overhead irrigation also reaches the plants, but the soil becomes rather dried out. Sometimes also in summer the plants look rather yellow, which is likely due to a lack of nourishment. Last week I cleaned up around them and found that as usual at this time of year, mice or other rodents have predated the stems. As well as one of their food sources, I've found balls of the leaves used as winter homes. I found them very snug and dry inside! Brent Hine Vancouver, BC UBC Botanical Garden zone 7a