LICHENS AND LICHEN. PARASITES

194 B.A.N.Z. ANTARCTIC RESEARCH EXPEDITION
PARMELIA GRISIWLA Dodge & Baker.
Parmelia griseola Dodge & Baker, Ann. M'o. Bot. Card., 25, 596 ; 1938.
Type: Marie Byrd Land, Edsel Ford Range, Slrua Gull Peak, P. Siple & S. Corey 72W-3.
Thallus up to 1 cm. in diameter, laciniae linear, convex, dichotomously branched, 0-24.3 mm.
broad, pruinose and eroded, pale olive buff, then greying and darkening, K rufescent; upper
cortex 2040p thick, pseudoparenchymatous, outer cells irregularly darkened, of thin-walled cells
about 4p in diameter, covered by a gelified layer 5-lop thick over the darkened areas, less developed
over the light areas; algal layer up to 30-50p thick, cells up to lop in diameter, protococcoid, some
imbedded in'the cortex; medulla 50-80p thiclr, of slender hyphae about 2p in diameter, loosely
woven, becoming more periclinal at the junction with the lower cortex which is 20-30p thick, of
periclinal hyphae 1-3p in diameter, only the outer ones darkened; rhizinae frequent, branched,
500-800p in diameter, of dark cells 20 X 1 .5-2p, longitudinally arranged, covered by a cortex about
5p thick, of short, thick-walled, dark cells, 4.5-9 X 2-4p, progressively longer and thinner within.
Only a few fragments ,referred here.
Queen Mary Land: David Island, C. T. Harrisson, A.A.E. 56-2; Hippo Nunatak, C. T. Har-
risson, A.A.E. 37.
USNEACEAE.
Thallus fruticose, erect, prostrate or pendent, attached to the substrate by a hapteron, radiate,
corticate with longitudinal hyphae in Alectoria and a few species of Ramalina, otherwise
cortex fastigiate somewhat pseudoparenchymatous; algae protococcoid (Trentepohlioid in Usnfa
sect. RocceUinue) ; medulla compact to arachnoid, often with a chondroid axis or strands of thick-
walled, pamillel hyphae, variously disposed. Apothecia circular, sessile or stipitate ; amphithecium
well developed; asci 1-8-spored; ascospores hyaline or brown, unicellular to muriform, thiclr-
walled.
Inner portion of cortex strengthened by strands of mechanical tissue ; medulla arachnoid ; spores
2-celled . . . . . . . . . . . . . . . . Ranzolina
Cortex not strengthened by mechanical tissue; medulla uniform or horny cartilaginous.
Cortex of conglutinate longitudinal hyphae ; thallus hollow, or very loosely stuffed Alectoria
Cortex a palisade of pseudoparenchyma; chondroid axis well developed and central Usnea
Thallus yellow to orange, variously blackened, especially the ultimate branches;
apothecial disc usually black . . . . . . . . Neuropogon
Thallus rarely yellow, ultimate branches not characteristically blackened ; apothecial disc
never black . . . . . . . . . . . . Ezcusnea
Thallus commonly distinctly articulate or moniliform, without pseudocyphellae,
stramineous, unchanged in herbarium or becoming fuscons in very old specimens
Stramineae
Thallus pale stramineous not changing in herbarium, with almost no ramuli,
smooth and shining . . . . . . . . . . . . Amoenae
Thallus not conspicuously articulate, divergently branched, smooth Glabratae
Thallus pale green when fresh, becoming deep brown in the herbarium.
Sparingly ramulose and subarticulate . . . . Pycnocladae
Neither ramulose nor subarticulate . . . . Osseoleucae
Thallus yellow stramineous, only the larger branches becoming brown in the
hebarium, neither ramulose nor subarticulate . . . . Xanthopoyae