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BFNA
Title: Bryolawtonia |
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XX.
BRYOLAWTONIA Norris & Enroth, Bryologist 93: 328--331 * [For Elva Lawton,
1896--1993, American bryologist] Daniel H. Norris Plants frondose. Stems: primary stems stoloniferous
with microphyllous or heavily eroded leaves, secondary stems decumbent, sometimes appearing
prostrate, pinnately branched mostly in a single plane, with branches similar
one to another; paraphyllia absent, pseudoparaphyllia short and broad,
denticulate on margins. Leaves complanate, ovate to elliptic, margins plane but with
some recurvature at and sometimes before mid leaf , serrate beyond the
middle; costa single, ending before leaf apex; lamina cells thick-walled,
smooth, median cells short-elliptic, with rounded lumens, alar cells quadrate
to transversely elongate in a large group.
Seta smooth and erect, to
15 mm. Capsule exserted, cylindric. Peristome
teeth 16, horizontally striate,
linear; endostome well-developed but shorter than exostome, segments
perforate, cilia 2, appendiculate. Species 1 (1
in the flora); w North America. Bryolawtonia has complanate leaves with broadly
rounded, serrulate margins. In the
field, Bryolawtonia can be confused
with Dacryophyllum falcifolium, an
endemic genus of the Hypnaceae restricted to the Central California
coast. Dacryophyllum is similar
in size to Bryolawtonia but differs
in possessing cultriform-asymmetric leaves unlike the almost symmetric-leaved
Bryolawtonia. Porotrichum bigelovii of west coastal
North America has complanate leaves with broadly rounded, dentate apices but that plant is markedly larger
than Bryolawtonia, and has leaves
appearing asymmetric as a result of broad recurvature of the postical margin. Bryolawtonia is a recent generic name for a plant once called Bestia vancouveriensis, a plant with a
long nomenclatural history (D. H.
Norris and E. J. Enroth (1990). There
are few similarities between the plants in these two now accepted monotypic
genera. SELECTED
REFERENCES: Lawton, E. 1971.
Moss Flora of the Pacific Northwest. Nichinan. Norris, D. H. and E. J. Enroth. 1990. Description of Bryolawtonia Norris & Enroth with observations on the Genus Bestia. Bryologist 93: 328--331. Norris, D. H. and J. R.Shevock. 2004. Contributions toward a bryoflora of
California. II. A key to the
mosses. Madroño 51: 133--269. 1. Bryolawtonia vancouveriensis
(Kindberg) D. H.
Norris & E. J. Enroth, Bryologist 93: 328--331. 1990 Thuidium vancouveriense Kindberg, Bull. Torrey Bot. Club 17:
277. 1890; Bestia holzingeri (Renauld
& Cardot) Brotherus; B.
occidentalis (Kindberg) Grout; B.
vancouveriensis (Kindberg) Wijk & Margadant; Heterocladium vancouveriense (Kindberg) Kindberg; Hypnum occidentale Sullivant &
Lequereux; Isothecium occidentale (Kindberg)
R. S. Williams;Porotrichum
vancouveriense (Kindberg) H. A. Crum; Pseudoleskea
occidentalis Kindberg; Pseudoleskeella
vancouveriensis Kindberg) Kindberg; Thamnium
vancouveriense (Kindberg) E. Lawton; Thamnium
holzingeri Renauld & Cardot Plants small, glossy dark-green to olive or
brownish green. Stems: an
inconspicuous prostrate and microphyllous stolon giving rise to a series of
plumose decumbent to ascending axes to 3 cm; stem transverse section with
4--5 outer layers of rather thick-walled cells forming an ill-defined
stereome over the 2--4 layers of larger inner thin-walled cells without a
central strand; axillary hairs 2--3
celled, to 100 \um with one basal brown cell, not offset from leaf insertion;
rhizoids red-brown, 6--8 \um, smooth, inserted on stem immediately below
abaxial costal insertion. Leaves to
1 mm, 2--3.5:1, not plicate, broadest near base, sometimes contracted at the
middle into a ligulate distal portion, rounded to obtuse at apex, imbricate
when dry and little changed when moist; laterally inserted leaves asymmetric
with their postical margins broadly incurved at base; margins at base
somewhat cordate but not decurrent, serrulate to serrate above the middle,
sometimes serrulate throughout; median cells smooth, 6--9 \um wide, 2--5:1,
thick-walled with lumen/wall ratio to 1: 1, but not pitted; alar cells
quadrate to transversely elongate in a group up to 10 cells in each
dimension, thick-walled, grading into laminal cells; apical cells rhomboidal, nearly
isodiametric; costa extending ca.1/2--3/4, often forked distally. Sexual condition dioicous; male
plants smaller than females, perigonia
on main axis or terminal on short lateral branches; perichaetia on main axis,
to 3 mm in an acicular cluster, strongly convolute around the seta,
perichaetial bracts ecostate or with a narrow costa present only near mid
leaf, abruptly acuminate from a ligulate-lanceolate base, cells
long-rectangular, to 12:1. Seta 5--10 mm, short-exserted. Capsule
brown, curved and inclined, not distorted or sulcate when dry, somewhat
strangulate; urn to 1.8 mm, about 2--3:1;
exothecial cells 1--3:1, 12--18 \um wide, thick-walled with a
lumen/wall ratio about 3:1; stomata restricted to neck; operculum
short-rostrate, about 1/2 as long as urn; exostome horizontally striate
basally, becoming low-papillose distally, red-brown; endostome segments
lightly papillose, open on keel, narrow, nearly as long as exostome with
basal membrane about 1/4 of total length; cilia 2, well-developed. Spores
low-papillose, 12--15 µm. Capsules rare,
mature spring. Broad-leaved trees, rock; 200--1000 m; B.C.; Calif., Oreg.,
Wash. Bryolawtonia vancouveriensis is a plant mostly epiphytic on
broad-leaved trees but also on moist rock.
In northern parts of its range deciduous angiosperms such as Alnus are its major phorophytes . To the south, it is especially abundant on
the burls of Umbellularia. It reaches its southern limits in
Monterey County, California and can reliably be expected in nearly any moist
coastal valley from the Bay Area of California to central coastal British
Columbia. A form of Bryolawtonia
vancouveriensis has been called
Bestia occidentalis (Kindberg) Grout.
This is very different in leaf arrangement (erect and pressed to
stem); in leaf shape (broadest at the base and approaching acute at the
apex); and branching pattern (clustered near the top of the decumbent
axis). It is immediately
recognizable. Nearly all the plants of
this morphology are found in coastal British Columbia and Washington. I have found, however, too many
intergradations in this form throughout the range of Bryolawtonia vancouveriensis, and deem it unworthy of species
recognition. |
