Making Sense of Moss Cushions on Rock

The many cushion mosses on rock can be rather confusing. In trying to figure it out for myself, I have put together this table that might be useful for others. Each species is linked to "research grade" observations in iNaturalist and an illustration from other places on the web (Flora of N. Am, Eflora BC, British Bryological Society Treatments)

Species	Leaf Length	Margins undulating	Clear hairpoint present	Contortion in dry state	Colour	Habitat	Other Features	Illustrations
Grimmia torquata	~1.5 mm	No	Present, very small	Leaves spirally twisted around stem	Dark Green	Shaded siliceous rock along vertical faces, sea level to subalpine	Forms exceedingly dense cushions	Illustration
Anoectangium aestevium	<2 mm	Absent	Absent	slightly contorted	Bright yellow-green	Open calcareous-siliceous rock, Sea level to alpine	Bright yellow leaves, relatively uncontorted leaves are unique	Illustration
Amphidium californica	2-4 mm	No	Absent	Leaves twisted but not around stem	Emerald Green	Shaded siliceous rock crevices, Sea level to montane	Leaf margin toothed near tip	Illustration
Amphidium laponnica	2-3 mm	Absent	Absent	Leaves twisted but not around stem	Emerald green	Shaded or open silicious rock, Sea level to Subalpine	Short sporophytes with ridges capsules common, leaf margins smooth throughout	Illustration
Tortella tortuosa	3-7 mm	Yes	Absent	Leaves contorted	Brown below, yellow green above	Calcareous and silicious rock, occasionally trees, all elevations	Forms loose cushions, leaf bases are clear under hand lens	Illustration
Gymnostomum aeruginosum	~1 mm	Absent	Absent	Slightly twisted	Reddish below, dull green above	Calcareous rock, All elevations	Capsules often present, lacking teeth	Illustration
Hymenostylium recurvoistre	~1 mm	Absent	Absent	Appressed and wavy when dry	Light green	Calcareous rock, all elevations	Typically encrusted with lime	Illustration
Hymenoloma crispula	2-3.5 mm	Absent	Absent	Strongly contorted and curled	Yellow green	Fully Exposed Calcareous and Siliceous Rock, Sea Level to Alpine	Tall, slender, erect sporophytes common	Illustration

Posted on March 3, 2023 03:05 AM by

rambryum

Making Sense of Moss Cushions on Rock

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