9. P. scortea Ach. Lich. Univ. (1810) p. 401.—Thallus orbicular,
subcoriaceous, smooth, somewhat shining, very th in ly isidiose in th e
centre, sinuato-lobed, greyish-white or w h itish ; beneath rugose,
brownish, deusely black-fibrillose ; lobes short, rounded, undulate,
iuciso-crcnate a t th e margins (K+yehowish^ Jredclish)-
thecia moderate, scattered, reddish-brown, th e margin su b en tire ;
spores 0,007—11 mm. long, 0,005—7 mm. thick.—Sm. Ling. F l. v.
p. 2 0 3— Parmelia tiliacea var. scortea Aludd, Alan. p. 9 3 ; Cromb.
Licli. Brit. p. 33 ; Leigbt. Lich. Fl. p. 131, od. 3, p. 122. TAchen
scorteus Ach. Prodr. (1798) p. 119 ; Eng. Bot. t. 2065.— B r it. Exs. :
Leight. 11. 87 ; Larb. Cæsar. n. 18.
Closely allied to P. tiliacea ; but its tliiclicr and less appressed thallua,
its normally whiter colour, tbe central isidia, the form of the lohes, and
the more scattered apothecia warrant us iu regarding it, with the older
authors, as a distinct species, in wliich light also it is now viewed hy
Nylander (Pyr. Or. p. 5). The isidia, whicli are greyish, becoming
blacki.sh in age, though chiefly central, are sometimes sprinkled over tlie
thallus nearly to its circumference. In this country, as elsewhere, the
apothecia are very rare, and even when present are but few. The sper-
luogoiies, Avhich are more comiiiou, are similar to those of P. tiliacea.
laud.—B, AI. ; L ’Etacq, Island of Jersey; Island of Sark. Near Bury
St. Edmunds, Suffolk; near Lewes and Henfield, Sussex; Shanklin,
Isle of AAight: New Forest, Hants; Bolt Head, Devonshire; Stonehenge,
AA ilts ; Harboro’ Alagna and Neivbold-on-Avon, AA’arwickshire;
TAvj’crop, Leicestershire; Little Stretton, Shropshire; Holyland, Pembrokeshire;
Dolgelly and near Barmouth, Alerionethshire; Island of
Anglesea ; Stokesley, Cleveland, Yorkshire ; near Eglestone, Durham ;
near Stavely, Kendal, AVestmoreland. Near Dumfries ; Castle Douglas,
Kirkcudbrightehire. Askew AVood and Dunkerron, co. Kerry.
Form concrescens Cromb.—Thallus orbicular, small, isidiose;
lobes very short, narrowly dissected and crowded. Apothecia u n known.
A qianniform condition, referred to in Leight. Lich. Fl. ed. 1, p. 13.3, as
approaching \ ta-, concentrica of F.revolvta. I t is, hoAvever, neither spherical
(hut only somewhat convex) nor free ; while the isidia and other characters
show that it belongs to P. scortea. The specimens seen are
sterile.
Hab. I l l crevices of stone Avails in a maritime district.—Histr. Ex-,
tremely local and rare in S.AA’. England.—B. AI. : Bolt Head, S. Devon.
10. P. saxatilis Aoh. Aleth. (1803) p. 204.—Thallus orbioulari-
expanded, membranaceous, subimhricate, reticulato-rugulose, often
somewhat isidioso-scabrid, greyish-white or glaucous-grey, beneath
black, rhizineo-fibrillose ; laciniæ sinuato-incised or sinuato-lohod,
retuse a t the apices ; C aC lI). Apotheoia
moderate or somewhat large, badious or brownish, th e margin thin.
entire or oren u la te ; spores 0 ,0 1 4 -1 9 mm. long, 0 ,0 0 9 -1 2 mm.
thiok.—Gray, Nat. Arr. i. p. 410 : Hook. IT. Scot. ii. p. 5 3 ; Sm.
Eng. Fl. V. p. 199 ; Tayl. in Alack. Fl. Hib. ii. p. 144 ; Aludd,
Alan. p. 9 4 ; Cromb. Lioh. Brit. p. 3 4 ; Loight. Lioh. F l. p. 137,
ed. 3, p. 126.— Lichen saxatilis Linu. Sp. PI. (1753) p. 1 1 4 2 ;
Huds. F l. Augl. p. 531 ; Lightf. Fl. Soot. ii. p. 816 ; AVibh. Arr.
ed. 3, iv. j3. 33 ; Eng. Bot. t. 603. TAchenoides vulgatissimwn
cinereo-glaucum laciniosuin et cirrhosum Dill. AIuso. 118, t. 24.
f . 83 a . Lichenoides cruiita foliosa, superne cinereo-glauca, inferne
nigra et cirrhosa, scutellis nigricantibus Dill, in Hay, Syn. ed. 3,
p. 72, n. 16.—Under th e type Avas included also tho following form
by most of our earlier authors.—B r it. E.vs. : Leight. n. 203 pro
parto ; Cromb. n. 27.
This Avell-knOAvn species is readily recognized by the reticulato-rugulose
thallus. Often very widely spreading, it is one of the largest plants
of the genus, and though sometimes suhsmooth is usually isidioso-scahrid
o il the rugæ. I t is seldom fertile, the apothecia, Avhich are at first urceolate
and moderate, becoming at length large and fiexiiose. Tlie spermogones,
which are not uncommon, are very minute, black, with spermatia
0,007 mm. long, about 0,001 mm. thick. The parasites Hothidea homosteipii
Nyl. and Ahrothallus parasiticus Nyl. (Lichen parasiticus Sm. Eng. Bot.
t. 1800) are often met with on the thallus of this species and of the form
here described.
Hah. On trees, walls, rocks, and boulders in upland aud suhalpine,
sometimes in lowland districts.—Histr. Irecal throughout Great Britain ;
rare in the Channel Islands; not seen from Ireland.—B AI. ; Island of
Guernsey. Near Brighton, Sussex ; Basingstoke, Hampshire ; near Penzance,
Cornwall; Alalvern Hills, AA’orcestershire; AA’rekiii Hill, Shropshire;
Lambeth, S. AA’ales; Island of Anglesea; Stavely, Westmoreland.
Appin, Argyleshire ; Killin, Ben LaAvers, Abernethy, Black Wood
of Hannoch, and lien Vrackie, Perthshire ; Cortachy, Forfarshire ; Por-
tletlien, Kincardineshire ; Corriemulzie, Braemar, Aberdeenshire ; Ben
Nevis, Inverness-shire.
Form furfuracea Schær. Spio. (1840) p. 4 55.—Thallus muoh
expanded, greyish-white, densely covered with greyish-brown
isidia : otherwise as in the type.—Aludd, Alan. p. 95 ; Leight. Lich.
Fl. p. 138, cd. 3, p. 127 ; Cromb. Linn. Soo. Journ. Bot. xvii.
p. 573.— J^armelia horrescens Tayl. in Alack. Fl. Hib. ii. p. 144
Jiro parte.—TAchenoides vulgaiissimum cinereo-glaucum lacunosum et
cirrhosum Dill. AIusc. 188, t. 24. f. 83 o, n.—B rit. Exs. : Leight.
n. 46 pro pa rte ; Larb. Lioh. Hb. n. 211 ; Bohl. n. 11.
Remarkable on account of the isidiose furfur with which it is frequently
covered and which obliterates the lobes except at the circumference,
giving it a panniform appearance. Smaller and sterile states in this condition,
and some very sparingly isidiiferous, are the form panniformis
(Cromb. Grevillea, xv. p. 75). The thallus is often dark-grey, and occasionally
becomes centrifugal from the decay of the central portions, when
it may present merely a narroAV circumferential border. The apothecia,
which are frequent, have the thalline margin sometimes exa.sperate Avith
the isidia.
Hah. On rocks, Avails, and trees, chiefly in upland districts.—Histr.
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