POLY SIP i i ON IA thuyoides.
Thuja-like Polysiphonia.
CRYPTOGAMIA Alga;.
Gen. Char. Frond longitudinally striate with internal
parallel tubes, bearing ovate capsules, and
granules in distorted ramuli.
Spec. Char. Stems erect, rising from creeping fibres,
terete; below simple and set with short spinelike
ramuli; above much branched; branches
crowded, very erect, bipinnate ; pinnae pinnato-
multifid ; axils rounded ; ramuli marked at short
distances with transverse striae as if jointed ;
veins reticulated.— Haw.
Syn. Polysiphonia thuyoides. Harv. in FI. Hib. pt. 3.
205. Man. Brit. Alg. 86. Wyatt Alg. Damn,
no. 305.
O N rocks attached to corallines, &c., growing in dull brown
or yellowish tufts, 2-3 inches long. Threads rather thick,
rigid, rising from a creeping base, naked below or furnished
with a few bristly branchlets, divided into a greater or less
number of erect branches above, which are clothed with
pinnate ramuli, which are themselves more or less regularly
pinnate, with the tips of the pinnules sometimes bifid or more
rarely trifid. Ultimate ramuli incurved. Articulations faintly
marked, especially in the lower portions of the plant, or filled
with numerous more or less anastomosing tubes. Granules
quaternate in the swollen ultimate ramuli. Capsules rare,
ovate. * Antheridia bright yellow, gelatinous, produced in
summer,’ when the ultimate ramuli are terminated by long
pellucid threads.
This species, of which we have received specimens from
Mr. Ralls, appears to be not uncommon. It has the habit
of P. nigrescens, and is allied to Polysiphonia fruticulosa, but is
very distinct. We are not aware that it has been described
by any foreign author. The capsules, which are very rare,
we have received from Mrs. Griffiths.—M. J. B.