Hypnum laxatum Mitt.

Landcare Research, Lincoln, New Zealand (CHR)
NY no.: 267964
Hypnum laxatum Mitt., Hooker's J. Bot. 8: 264
(1856). Lectotype: Victoria, Gipp's Land, Dr.
Mueller 120, NY-Mitten! (Designated by
Hedenäs, Nova Hedwigia 62: 461, 1996)
Confirmed: Allan Fife April 2004
Rhynchostegium laxatum (Mitt.) Paris, Index
bryol. 1131 (1898).
Original description based on Lectotype ex Victoria,
NY-Mitten and TWN Beckett 74 ex Akaroa, New
Zealand (CHR)
Plants small to moderate in size, yellowish-green or
??, lustrous, forming interwoven mats with
ascendant (mostly 6-8 mm) branches. Stems
irregularly to subpinnately branched, c. 20 mm -??
decumbent, in cross-section with 3-5 layers of thick-
walled outer cells and a distinct central strand;
rhizoids smooth, brown, in scattered or dense
fascicles on very surface of stem. Stem and branch
leaves differentiated by shape, when dry ± striolate
and more erect than when moist. Stem leaves
broadly ovate to oblong-ovate, abruptly tapered to
an narrowly acuminate or filiform apex (acumen
mostly 0.45-0.6 mm and up to c. 0.4 the total leaf
length), weakly concave, narrowed to base (not
cordate) erect to spreading, weakly decurrent,
1.4-1.9 x 0.6-c. 1.0 mm (including acumens), entire
or denticulate above; mid laminal cells linear-
rhombic, smooth, firm-walled, mostly 54-90 × 7-9
µm; cells of the acumen not differentiated; cells
at insertion shorter, thicker-walled and porose in
several rows; alar cells slightly inflated or
subquadrate in a poorly differentiated group.
Branch leaves ovate-acuminate, mostly 1.2-1.6 x
0.4-0.5 mm, erect-spreading when moist, erect and
weakly striolate when dry; mid laminal cells linear-
rhombic, smooth, firm-walled c. 60-90 × 7-9 µm,
becoming longer in lower leaf and shorter and
broader at insertion; alar cells subquadrate and
mostly weakly inflated, forming a medium-sized
but poorly defined group. Costa variable in length,
single or rarely slightly forked, (1/3-) ½-⅔ the
leaf length, tapered, lacking a terminal spine.
Autoicous. Perichaetia c. 2.0 mm long, the inner
leaves acuminate from an oblong base, erect,
ecostate. Perigonia scattered on stems &
branches, c. 0.6-0.8 mm, paraphyses not seen.
Setae slender, flexuose, twisted to the left, 12-
15 mm, red-brown, smooth; capsules oblong-
cylindric, curved and asymmetric, red-brown,
narrowed below mouth when dry, inclined to
horizontal, 1.4-1.8 mm; exothecial cells
oblong, firm-walled, distinctly or weakly
collenchymatous; stomata ??; annulus
differentiated, adhering to the operculum;
operculum long rostrate from a conic base, c. 1
mm, curved & distinctly shorter than the theca.
Exostome teeth yellow-brown, lanceolate and
shouldered, bordered, transversely striate (not
striolate!) on the outer surface, trabeculate on
inner surface, c. 450µm; endostome from a
high membrane, with segments perforate,
nearly the height of teeth; cilia single and
elongate, details not observed (apparently not
nodose or appendiculate) Calyptra not seen.
Spores 13-15 µm, green, nearly smooth.
Allan Fife April 2004
Rhynchostegium laxatum (Mitt.)
Found in Euchynchium cover in Herb.
PRESENTED DECEMBER, 1906
Mitten
Hypnum laxatum
Mitten
Landcare Research, Lincoln, New Zealand (CHR)
No. NY 267964.
costae of branch leaves lacking a
terminal spine
Determinavit: Allan Fife 
*Hypnum laxatum*
*Rhynchostegium laxatum*

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