Historically, this probably stems from (i) the assumption among botanists that there are very few mosses in the desert, (ii) the difficulty of collecting and detecting moss populations due to heat, dry conditions, and wind, and (iii) the lack of adequate floras and species checklists for the Mojave.
(this; probably stems; from (i) the assumption among botanists)
this
probably stems
from (i) the assumption among botanists