Platygyrium

  1.Plants with stems and leaves… 2

2.A) Leaves equally spaced around stem, or in two ranks with a midrib… Musci (p. 23)

1.   B) Gametophytes present with obvious leaves… 2

2.  B) Leaf cells of one kind (green), or if of two kinds, branches never in clusters...3

3. B) Leaves attached all around the stem (foliate stems sometimes flattened [complanate])…7

7. B) Leaves without lamellae or filaments on the adaxial surface of the costa (but propagula sometimes present)…23

23. B) Leaves never lobed, flattened (although sometimes concave with margins inrolled or recurved)…24

24. Leaves without a costa or costa short and double, double, or single with 2-3 lateral spurs…25 

25. B) Lamina unistratose…27

27. B) Upper leaf cells smooth…46

46. B) Leaves concolorous at apex…48

48. Plants sometimes in wet habitats but never occurring submerged; leaves various but never keeled…49

49. B) Plants pleurocarpous, mostly larger…53

53. B) Costa always double, or if single very short and without supplementary costae…54

54. B) Costa short and double, usually ending just above leaf base…59

59. B) Leaves acute to acuminate, at least apiculate; plants mostly larger, widespread…61

61. B) Leaf cells firm- to thick-walled, rounded to linear…63

63. B) Leaves not at all decurrent to broadly auriculate…64

64. Plants larger; leaves more than 1 mm long…67

67. Leaves falcate-secund.

68. Leaf cells more or less linear…70

70. Plants irregularly pinnate to unbranched, not feather-like; stems prostrate to loosely ascending…71

71. Mature branches erect and producing abundant and conspicuous propagula in their upper leaf axils… Platygyrium

Key: http://www.mobot.org/plantscience/bfna/V1/KeyToMosses_2.htm