T l a t e e C Z IIT V .
H.B.&R.imp.
Ser. E hodospermeæ.
P l a t e CCLXXIV.
CALLITHAMNION ARBUSCULA, Lyngh.
G e n . C h a b . Frond rosy o r b row n ish -red , filam e n to u s ; stem e ith e r opake
an d c ellular, or tra n s lu c e n t a n d jo in t e d ; b ra n c h e s jo in te d , o n e -tu b ed ,
mostly p in n a te (rarely d ichotomous or ir r e g u la r ) ; dissepiments h yaline.
Fruit of tw o k in d s , on d is tin c t p l a n t s ; 1 , external^ tetraspores, s c a tte
re d a lo n g th e u ltim a te b ra n c h le ts, o r b o rn e o n little p e d ic e ls ; 2 ,
ro u n d ish o r lobed, b e rry -lik e re c ep tac le s (favella) s ea ted o n th e mam
b ra n ch e s , a n d co n ta in in g n um e ro u s an g u la r spores. C a l l i t h a m n i o n
(L y n g h ), from koWos, beauty, a n d bagnov, a little shrub.
Callithamnion arbuscula-, stem s n a k ed below, in a rtic u la te , ro b u s t, c a r tila
g in o u s , th e m a in divisions set w ith sh o rte r b ran ch e s , w hich are
densely c lo th ed o n a ll sides w ith m in u te , im b ric a ted , p in n a te d ram u h
(plum ules) ; u ltim a te p in n u le s simple or forked, re curved, a cu te,
a rticulated^ th e a rticu la tio n s twice as lo n g as b ro a d ; te tra sp o re s gio-
bosBj n um e ro u s , sessile on th e u p p e r edge of th e p in n u le s .
Callithamnion ai-buscula, Lyngh. Hyd. Ban. p. 123. t. 38 Harv in Eoolc.
Br. M. vol. ii. p. 340. Harv. m Mack. FI. Hii. p a rt 3. p. 213. Harv.
Man. ed. 1. p. 105.
P hlebothamnion arbuscula, Kiitz. Sp. Alg. p. 656.
D asya spongiosa, Ag. Sp. Alg. vol. ii. p. 121.
CONEBETA arbuscula, S. Br. - Billw. t. 85. (excl. t. G.) F. Bot. 1 .1916.
H ab On rooks and mussel-shells, near low-water mark, usuaUy in places
left bare on the recess of the tide ; also in tide-pools. Perennial.
Summer and autumn. Abundant on the western shores oi Scotland
and Ireland ; rare on the eastern. Frith of Forth, B rs. Greville a ^
Arnott. Aberdeen, common, B r . BicUe. Orkney, B ev. J . H .
Pollexfen.
Geoge. D is t e . The Ferroe Islands (and probably elsewbere in the Northern Sea).
D e sc e . Boot a fleshy, conical disc. Fronds several from the same base, from
two to five or six inches high, as tHck as smaU twine below attenuated
upwards, opake, and without visible articulation, much branched and shrublike
Stem naked below, densely set with lateral branches above, and
these furnished with other smaller ones, spreading on aU sides and making
a bushy or shrub-like head. The lesser branches, which are from a quarter
to half an inch in length, are densely clothed with minute c osely imbricated
plumules, a line or two in length, which make each little branch
cylindncal, and. being very dense towards the tips, give th e apices ot the
branches a striHngly blunt, corymbose aspect. The plumnles have a flexuons
rachis, set with alternate, simple, or once forked, horizontally patent oi
reflexed pinnules. Favellæ of small size, binate or clustered springing
from the rachis of the plumules. Tetraspores sessile, spherical, oi small