Polytrichastrum sexangulare var. vulcanicum

(C. E. O. Jensen) G. L. Smith

Bryologist 95: 270. 1992,.

Basionym: Polytrichum sexangulare var. vulcanicum C. E. O. Jensen Bot. Tidsskr. 20: 109. 1896
Synonyms: Pogonatum sphaerothecium Polytrichum sphaerothecium
Treatment appears in FNA Volume 27. Treatment on page 129.

Plants small, forming large brownish mats. Stems with 5–6 layers of thick-walled cortical cells. Leaves incurved and closely appressed to the stem when dry, erect-spreading when moist; sheath poorly delimited; marginal lamina expanded and involute, covering the lamellae; perichaetial leaves abruptly narrowed to the blade. Seta arcuate with age. Capsule nearly globose, horizontal to nodding; peristome teeth 32, short, attenuate, the alternate teeth often smaller.


Habitat: Volcanic rocks
Elevation: high elevations

Distribution

V27 155-distribution-map.gif

B.C., Alaska, e Asia (Japan), Atlantic Islands (Iceland)

Discussion

Variety vulcanicum is notable for the rather thick, curved seta, nodding, globose capsule, and the stem cortex composed of very thick-walled cells, in contrast to the thin-walled cortex of var. sexangulare. It is probably best considered a variety of P. sexangulare, despite its distinctive peristome and the absence of capsule angles. E. Lawton (1971) described intermediate forms in British Columbia with acute-tipped leaves and angled capsules, but with the stem cortical cells and peristome of var. vulcanicum.

Selected References

None.

Lower Taxa

None.

"um" is not declared as a valid unit of measurement for this property."broader" is not a number. "wide" is not a number.

prominent +
Gary L. Smith Merrill +
(C. E. O. Jensen) G. L. Smith +
toothed +
differentiated +
Polytrichum sexangulare var. vulcanicum +
distinct +
tubular +  and lanceolate +
broadened +
thick-walled +
not pitted +  and papillose +
monoicous +, dioicous +, sexual +  and vegetative +
sparsely ciliate;smooth +
cucullate +
horizontal;nodding +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
excurrent +  and percurrent +
prolonged +
mucronate +  and cucullate +
undifferentiated +
B.C. +, Alaska +, e Asia (Japan) +  and Atlantic Islands (Iceland) +
high elevations +
scabrous +, mammillose +  and smooth +
Volcanic rocks +
cylindric +  and tapering +
photosynthetic +
5 +  and 8 +
serrate +, crenulate +  and serrulate +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
membranous +
1(-3)-stratose +
papillose +  and smooth +
crenulate +  and serrulate +
shape +  and size +
polygamous +, dioicous +  and sexual +
narrowly ovate;pyriform +
sharply toothed +  and entire +
interwoven +
large +
toothlike +
underground +
undifferentiated +
arcuate +  and straight +
1.5 cm15 mm <br />0.015 m <br /> (3 cm30 mm <br />0.03 m <br />) +
hyaline-margined +
elongate-rectangular +
tapering +
differentiated +
larger +  and minute +
secund +  and simple +
erect-spreading +
cucullate +
1 cm10 mm <br />0.01 m <br /> (3 cm30 mm <br />0.03 m <br />) +
Pogonatum sphaerothecium +  and Polytrichum sphaerothecium +
Polytrichastrum sexangulare var. vulcanicum +
Polytrichastrum sexangulare +
variety +
unjointed +
triangular +
smaller +
dark green +  and reddish-brown +