THE TUNBRIDGE EILM PERN.
HYMENOPHYLLUM TUNBRIDGENSE.
H. fronds pellucid-membranaoeous, ovate or oblong, more or less
elongated, pinnate ; pinnæ subvertioal, pinnatifid, deourront forming
a wing to the raohis ; segments linear, undivided or bifid, and, as
wen as the upper margin of the roundish valves of the axillary
solitary sessile compressed involuoros, spinulosely serrate. [Plate
OVIII.]
H y m e n o p h t l l u m t u n b r i d g e n s e , Smith, Mem. Acad. Roy. Sc. T u rin , v. 418 ;
Id ., Eng. Bot. iii. t. 162 ; Id ., Eng. Fl. 2 ed. ir . 313, Hooker, Sp. Fil.
i. 95 ; Id ., Oen. F il. t. 32 ; Id ., Fl. Bond. iv. t. 71. Hooker A AmoU,
BrU. PI. 7 ed. 592. BaUngton, Man. Brit. Bot. 4 ed. 428. Mackay, Fl.
Hib. 345. Deakin, Florigr. Brit. I t. 122, fig. 1616. Neuman, Uist. BrU.
Ferns, 3 ed, 297. Moore, Handb. BrU. Ferns, 3 ed. 262 ; Id ., Ferns o f Ot.
Brit. Nature Printed, t. 49 A. Lowe, Nat. Hist. Ferns, viii. t. 5 B.
Sowerby, Ferns o f Gt. Brit. 75, t. 42. Bentham, Handh. Brit. Fl. 638.
Gray, Nat. A rr. BrU. PI. ii. 19. Willdenow, Sp. Plant, v. 520. Sprengel,
Syst. Yeg. iy. 133. Presl, Hymenophyll. 32. Hooker fil., PI. New Zealand,
ii. 11. Nyma n , Syll. Fl. Europ. 434.
H y m e n o p h y llu m a s p e r u lu m , Kunze, L in . ix. 109. Presl, Hyrmnophyll. 32.
H y m e n o p h y llu m T h u n e e r g i i , Beklon, Sehed. PI. Exsic. Cap. 92 ; according to
Kunze. Fresl, Hymerwphyll. 32.
T r ic h o m a n e s t u n b r i d g e n s e , Linnæus, Sp. Plant. 1561. Hedwig, Fil. Gen.
ivitli figure (t. 17). Flora Danica, t. 954.
T r ic h o m a n e s p u l o h e l l u m , Salisbury, Prod. 404.
Caudex rigid, filiform, creeping, branched, dark brown, forming
dense entangled carpet-Kke masses ; furnished about the base of the
fronds with a few hair-like scales. Fibres slender downy.
Vernation oiroinate.
Stipes slender, wiry, terete, varying from one-third to one-half
the length of the frond, often sKghtly margined or winged in the
upper part; lateral at intervals along the caudex, to which it is
adherent. EacMs winged.
Fronds smooth, pellucid-membranaceous, minutely oeUular, deep-
oKve or sometimes full olive-green, from one to four or six inches
long, usuaUy ovate, lanceolate-ovate, or oblong, more'‘or less elongated,
pinnate helow. Pinnce or primary divisions alternate,
deourrent so as to form everywhere, except at the base of the
larger fronds, a narrow entire wing to the rachis ; distichous, asooud-
ing or sub-vertical, nearly rhomboid in circumscription, furcately
hipinnatifid, that is to say, twice divided with the ramifications on a
dichotomous or forked plan, the divisions alternating, and so placed
as to show an apparent excess of development on the anterior side
caused, as may bo seen, by tbe medial or axial vein, which may he
recognised, curving upwards. Ultimate segments linear, obtuse,
spinulosely serrate.
Venation consisting of a series of dichotomous ramifications (two
or three times repeated) of the wiry ribs which branch alternately
from the main raohis, each ultimate segment having one of these
divisions along its centre, and not quite reaching to its apex. Thus
the fronds might be said to consist of slender branching wiry
ribs everywhere bordered with a flat delicately cellular pellucid-
membranaceous margin.
Fructification usually produced iu the upper half of the fronds,
extra-marginal, i. e. the two valved involucres replace the lowest
anterior segment, and are projected outwards from the margin, the
opening being exterior. Sori consisting of numerous spore-oases
clustered around the short receptacle, on which they are sessile.
Receptacle formed of the altered apex of the vein (usually the lowest
anterior vein of the pinna) spongy, ohlong-clavate, free and central
within the involucre, and shorter than its valves, therefore included.
Involucres sessüe, supra-axillary i. e. borne in the axüs of the
pinnæ or primary divisions, short, compressed, the base somewhat
inflated, cuneate and more or less sunk in the segment, two-valved,
the valves semiorbioular, flattish, spinulosely serrate at the upper
margin. Spore-cases sessile, affixed obKquely, vertically compressed,
tKus lenticular, witK a transverse ring. Spores minute, irregularly
oblong, or triangular. In ordinary oases the lower anterior segment
of each pinnæ only is fertüe, hut sometimes one or more others are
also soriferous.
Buration. The rhizome is perennial. The fronds are also perennial,
growing up in the course of the summer, attaining their full
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