" i r r ”
370 L IC H E N A C E I. [ l EO-ANOEA.
Ilab On the tranks of old trees iu wooded districts.—D/str. Only m
S and W. England; no doubt to be detected elsewhere.—B. M. : VAal-
thamstow, Essex; Glynde, Sussex; uear Bradford, Wiltshire; Windsor
Great Park, Berkshire.
h. Theoæ 8-spored.
25. L. m ed ian s Nyl. Bull. Soo. Bot. F r. xiii. (1866) p. 3 6 7 .—
Thallus orbicular, minutely granuloso or leproso-granulose in th e
centre, plioato-radiose a t the circumference, opaque, vitelline-yellow
or citrine, greyish-white in the centre ( K - ). Apotheoia moderate,
plane, sordid-yellow or yellowish-brown ( K - ) ; the th allin e margin
en tire or orenulate, citrine ; spores oblongo-ellipsoid, simple, or oocasionally
1-septate, 0 ,0 1 1 -1 7 mm. long, 0 ,0 0 4 5 -6 5 mm. thick.
—Cromb. Grevillea, xviii. p. 45 ; Leight. Lich. F l. p. 206, ed. 3,
p. 189.—Placodium medians Nyl. BuU. Soc. Bot. F r. ix. (1862)
p. 2 62.—B rit. E.vs. : Larb. Lich. Hb. n. 59.
Externallv subsiniilar to L. murorum, to which at first sight it seems
allied, but differs in the absence of any reactions ^ud in the structure ot
the spores. The thaUus is at length somewhat expanded, becoming
almost leproso-dissolved in the centre, which is inspersed with citrine
I t is seldom fertile, though when present the apothecia are
mmierous.
Hnb. On calcareous roeks and walls in lowland and upland districts.—
Distr. Sparingly in Central and W. England.—B. M .; Pimbury Park,
Cirencester, Gloucestershire; Llanymynech Hill, Shropshire ; Denny
Abbey, Cambridgeshire.
26. L. e p ix a n th a Nyl. Act. Soc. Linn. Bord. t. xxv. (1864) p. 8.
—Thallus effuse, th in , granulose, yellow-vitelline or greenish-grey
(K _ ) , often subevanescent. Apothecia smaU, sessile, plane or
slightly convex, yellowish-orange or greenish-yellow (K—) ; th e
th allin e margin thin, suhcrenulate, pale-yellow; spores 8na?,
oblong or ellipsoid, simple, a t length polari-looular, 0,012-21 _mm.
long, 0 ,0 0 5 -7 mm. thick.—Cromb. Grevillea, xviii. p. 45 ; Leight.
Lich. F l. p. 206, ed. 3, p. 213.—Lecanora vitellina vars. epixantha
e t octospora Nyl., Cromb. Lich. Brit. p. 4 8 ; var. epixantha Leight.
Lioh. Fl. p. 181, ed. 3, p. 167. Lecidea epixantha Ach. Liob. Hniv.
(1810) p. 208.
Externallv scarcely distinguishable from Z. vitellina, but differs definitely
in the' number'of the spores. The thallus is entirely absent when
the plant grows, as it often does, mixed up with other lichens. A t times
the thalline margin of the apothecia is at length excluded.
Hab. On rocks and walls in maritime and upland situations.—Disfr.
Seen only from a few localities in S. England, Wales, and S. Ireland; no
doubt overlooked elsewhere, especially when athalline.—B. M .; Hastings,
Sussex; Cheddar, Somersetshire; Llandyssil, Cardiganshire. Giant’s
Stairs, CO. Cork.
L E C A N O EA .] L E C A N O -L E C ID E E I. 371
Subgen, 7. EULECANOBA Nyl. Not. Sallsk. pro F . e t Fl.
Fenn. Fiirh. n. s. v. (1866) p. 127.— Thallus crustaceous, granuloso
or leprose, very rarely radiate. Apothecia lecanorine or lecideoid ;
spores occasionally numerous, simple or variously septate, raroly
brown ; hymenial gelatine variously tinged with iodine. Spermogones
with jo in ted or simple sterigmata and various spermatia.
The largest subgenus of Lecanora and in several respects confluent
with the preceding suhgenera. According to the structure of the apothecia
and spermogones it is divided into different sections, most of which
have been viewed as distinct genera hy sporologists.
A. Spores 8næ (rarely 8-16næ), polari-bilooular, b
rarely simple or 1 -septate, colourless ;
hymenial gelatine, especially the thecæ,
is'?
bluish with iodine. Spermogones with
jo inted sterigmata and stra ig h t spermatia.
{Euealoplaca F r. til. Lioh. Scand. p. 172.)
a. Apothecia brig h tly coloured. {Callopis-
mella Wedd. Mém. Soc. Cherb. t. xix. p. 276.)
27. L. eitrina Aoh. Lioh. Univ. (1810)
p. 402 ; Nyl. Bull. Soo. Bot. F r. t. xiii. p. 366.
Fig. 03.
—ThaUus effuse, granuloso-leprose, rimoso-sub-
Lecanora cerina Ach.
areolate, citrine (K -|- purplish). Apothecia
—a. A spore, X
moderate, plane or somewhat convex, orange-
350. h. Jointed
sterigmata and
yellow (K 4- purple) ; th e th alliu e margin thin,
spermatia, X 500.
entire, a t length obliterated ; spores ellipsoid,
polari-bilooular, colourless, 0 ,0 1 0 -1 5 mm. long, 0 ,0 0 5 -8 mm. thick.
— Sm. Eng. Bot. ii. p. 192 ; Tayl. in Maok. Fl. Hib. ii. p. 138 ;
Cromb. Grevillea, xii. p. 61.—Placodium citrinurn Leight. Lioh.
Fl. p. 177, ed. 3, p. 163. P. murorum subsp. citrinurn Cromb.
Lioh. Brit. p. 45 ; var. e. citrinurn Mudd, Man. p. 132. Lichen
citrinus Eng. Bot. t. 1793 (three lower figs.). Verrucaria eitrina
Hoffm. Deutsoh. Fl. ii. (1795) p.. 198 pro parte. Liehen candelarius
Huds. F l. Angl. p. 444 pro p a rte ; With. A rr. ed. 3, iv. p. 27 pro
parte. Lichenoides crustosum, orbindis et scutellis jia v is Dill. Muse.
136, t. 18. f. 18 B.— B rit. Exs. ; Leight. n. 86 ; Larb. Lich. Hb.
n. 86.
Differs at once from Z. {Placodium) murorum, of which it has frequently
been regarded as a variety, in not being radiate at the circumference,
while connecting states are never found. The thallus occasionally
spreads extensively, varying somewhat in thickness, at times subevanescent,
and is often of a greenish-yellow colour when growing in shady
places, and in old plants is partially more or less greyish-citnne. The
apothecia when present (for the plant is often sterile) are generally
numerous, at first somewhat innate, becoming at length convex, with the
thalline margin excluded.
Hab. On the mortar of walls, rarely on rocks, very rarely on old
trunks ot trees, chieflv about towns and villages, in maritime, lowland,
2 B 2
--TIF