I92I. No. 7- STUDIES OX THE LICHEN FLORA OF NORWAY. I 97 



incisis, colore paginae superioris glauco-cinereo vel praecipue marginem ver- 

 sus fuscescens (numquam in virescentem vergens) et colore paginae infério- 

 ns apud nos semper niger, niargine late fuscescens. Thallus niargine et 

 plicis interdum leviter sorediose t'atiscens. 



Apud nos semper sterilis. 



Apothecia in tvpo americano ut \-idetur frequentia, margin c 

 thalli ant i ce affix a, sessilia vel subpedicellata, perforata, mediocria, 

 rotundata, diam. 4 — 5(10! mm. Discus castaneus, nitidus, subplanus, rugu- 

 losus; margo tenuissimus vel exclusus, postremo interdum radiatim ruptus. 

 Receptaculum reticulato-rugosum, thallo concolor. Cortex receptaculi 25 — 

 40 |x altus, incoloratus, hyphae perpendiculares, conglutinatae et indistinctae, 

 \alde pachydermaticae. Cortex interior non evolutus. Gonidia in 

 tota medulla inclusa, praecipue sub hypothecio numerosa. Hypothecium 

 incoloratum. Hymenium angustum : 40 — 45 (50) [j. altum, epithecium versus 

 sensim rufo-fuscescit, strato amorpho incolorato tectum, non inspersum. 

 Paraph y s es indistinctae, apice capitato-incrassatae (4 (x), indivisae vel 

 vulgo plus minus ramosae, parte interiore etiam ramoso- 

 connexae. Asci 30 — 35 [x longi, 18 — 15 [x crassi, saccati vel pvrifor- 

 mes, membrana apice mediocriter incrassata. Sporae distichae, ovales, par- 

 \ae: 6.8 — 8 |j. longae, 4 — 5.2 [x crassae. 



Pycnides (in specim. americ. examin.), omnino immersae, globosae, 

 diam. 120 [x, perifulcrium integrum, una cum cortice vicino thallino obscu- 

 ratum, pycnoconidia recta, an gus te cylindrica, 4.5 — 7 [x longa. 



R e a c t. Hymenium J e caeruleo mox sordide virescens vel fuscescens, 

 asci solum persistenter caerulescentes vel caeruleo-nigrescentes. Hypothe- 

 cium et interdum partes adjacentes medullae et medulla receptaculi J 

 persistenter caerulescentes. Medulla thallina J non caerulescens. 



Cetraria laciiuosa is a species of a \ery wide distribution, North Ame- 

 rica, Siberia, and Europe. But in our continent it is restricted to Norway, 

 and the S. W. and Central Scottish Highlands. Not mentioned in Adams: 

 The Distrib. of Lichens in Ireland (1909). — Bruce Flnk writes erroneously: 

 'The plant is strictly North American' (Minn., 1910, p. 201). 



First detected in Europe by Sommerfelt in Saltdalen (between 1818 

 — 1824, undated and undetermined), then by M. N. Blytt in Telemarken 

 (1826?), European plants first mentioned in literature by Til Fries in Lieh. 

 Arct. i860 p. 38. 



In America it presents several variations, described by Tuckerman 

 (var. stcnophylla, and var. atlantica, cfr. Krypt. \'ind. 1553, and Tuck. Lieh. 

 Amer. Sept. 6 — 1 have not seen the description in Tuck. Syn. p. 16). 



Our Norwegian plants are of a uniform habitus, with coarse, broad, 

 rounded, ascending and little incise lobes, dark under side, and more glaucous 

 upper side, they are always sterile. — American plants in our herb, are 

 more microphylline, more appressed and paler below. 



Attention should be called to this difference. 



