170 C. Warnstorf. 
2. Cellulae lamellarum in series 4—5; folia superiora 
ad 5—6 mm longa, sicca adpressa, humida erecto- 
patentia. — Photophiler Hochmoorbewohner. 
8. P. strietum. 
1I. Folia apice piligera: 
1. Cellulae lamellarum in series 5—6; folia superiora 
humida erecto-patentia; pilus foliorum tenuiter 
serrulatus. — Photophiler Xerophyt. 
9. P. piliferum. 
b) Cellula superior lamellarum sectione transversali ovata, apice 
pariete aut non aut valde incrassato levi vel papilloso instructa. 
a) Cellula superior lamellarum sectione transversali apice 
pariete tenui levi vel indistincte papilloso instructa. 
I. Folia superiora integra, apice piligera et marginibus late- 
ralibus angusteincurvatisinstructa ;pilus foliorumacute 
serrulatus. — Photophiler und xerophiler Bewohner 
der arktischen Tundren. 10. P. hyperboreum. 
II. Folia superiora serrata, apice non piligera et marginibus 
lateralibus paulo vel vix incurvatis instructa: 
1. Folia superiora 7—15 mm longa, sicca erecta vel 
irregulariter patula ad paulo recurvata vel non- 
nunquam spiraliter torta, humida falcato-arcuata. 
Cellulae lamellarum in series 4—5 (6); sectione 
transversali apice indistincte tenuissime papillosae. 
Skiophiler, mesophiler Waldbewohner. 
11. P. attenuatum. 
2. Folia superiora ad 10 mm longa, sicca adpressa vel 
irregulariter, patula, humida erecto-patentia. Cel- 
lulae lamellarum in series 5—6; sectione trans- 
versali apice glaberrimae. — Photophiler, hygro- 
philer Moorbewohner 12. P. graeile. 
5) Cellula superior lamellarum sectione transversali apice 
pariete valde incrassato instructa. 
I. Folia superiora serrata; cellula superior lamellarum 
sectione transversali apice papillis magnis instructa. — 
Photophiler, xero- und mesophiler Gebirgsbewohner, 
sehr selten auf Torfboden. 13. P. alpinum. 
II. Folia superiora integra; cellula superior lamellarum 
sectione transversali apice glaberrima. Folia plerumque 
subsecundo-falcata. — Photophiler Gebirgsbewohner 
und Bewohner der subarktischen und arktischen 
Region. 14. P. sexangulare. 
