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ROCCELLA | ROCCELLACE 479 
With the exception of Roccella, the genera of Roccellacee contain 
few species. All of them inhabit mainly the sea-coasts of warm 
countries. There is only one genus represented in Europe. 
Thallus cylindrical or strap-shaped, branched...... Roccella. 
ROCCELLA DC. Fi. Fr. ii. p. 334 (1805). (PI. 70.) 
Thallus fruticose of simple or branching fronds, greenish- or 
bluish-grey, mostly sorediate ; cortex of closely packed hyphal 
branches disposed at right angles to the surface (fastigiate) ; 
medullary hyphze more or less parallel with the long axis; 
gonidia in a zone within the cortex. Apothecia lateral on the 
fronds, mostly discoid, with a proper margin, and with or 
without a thalline margin ; hypothecium thick, black ; paraphyses 
branched ; spores elongate-oblong or fusiform, mostly 3-septate, 
colourless. 
The species of Roccella have a wide distribution, but only two are 
found as far north as the British Isles. They yield in more or less 
abundance a purple dye, the orseille or orchil of commerce. 
R. tinctoria, which is not British, is the best known and was one 
of the earliest recorded lichens. : 
1. R. fucoides Wain. in Welw. Cat. Afric. Plants, ii. 2, p. 433 
(1901).—Thallus of densely czspitose thickly and repeatedly 
branched fronds, rounded or slightly compressed, rather short 
(generally about 3-5 cm. high), more or less sorediate, basal 
sheath small, light bluish-grey (outer cortex CaCl + orange-red, 
inner tissue and soredia —, medulla I + blue). Apothecia small, 
somewhat prominent, black, without a thalline margin ; para- 
physes uneven, rather wider, branched and dark at the tips ; 
spores oblong-fusiform, 3-septate, 12-16 p long (or longer), 
3—4 p thick.—h. phycopsis Ach. Lich. Univ. p. 440 (1810) ; 
S. F. Gray Nat. Arr. i. p. 426; Cromb. Lich. Brit. p. 22 & 
Monogr. i. p. 182, fig. 37; Leight. Lich. Fl. p. 81; ed. 3, p. 74. 
R. tinctoria Hook. in Sm. Engl. Fl. v. p. 221 (1833) (non DC.) ; 
Mudd Man. p. 75 (incl. var. phycopsis); Leight. ll. c. Lichen 
fucoides Dicks. Pl. Crypt. fase. ii. p. 22 (1790) & L. Roccella 
op. cit. fase. iii. p. 19 (1793) (non Linn.); Engl. Bot. t. 211; 
With. Arr. ed. 3, iv. p. 42 (1796). 
Exsicce. Cromb. n. 14; Larb. Cesar. n. 11 & Lich. Hb. 
n. 122; Mudd n. 48. 
A rather stunted-looking bushy plant, abundantly sorediate and 
very rarely fertile. Spermogones are occasionally present, with 
spermatia 13-16 » long, 1 » thick. By earlier lichenologists it was 
confused with Lichen Roccella L. Sp. Pl. p. 1154, the well-known dye 
lichen, Roccella tinctoria DC. FI. Fr. ii. p. 354 (1805). The figure in 
English Botany was drawn from a specimen collected on Portland 
Tsland. 
Hab. On rocks, rarely on walls, in maritime localities.—Distr. 
Uncommon on the southern coasts of the British Isles, very rare in 
