Hygroamblystegium varium
Hygroamblystegium varium subsp. noterophilum
willow feather-moss
leaves ovate-lanceolate to ovate-triangular;
basal laminal cells short-rectangular, often pigmented, walls firm, eporose, region weakly differentiated;
medial cells 2–7:1.
leaves 1.2–2.4 × 0.3–1 mm, lamina sometimes partially 2-stratose, especially at base near costa;
margins entire or nearly so;
costa excurrent, 110–140 µm wide at base;
medial laminal cells 20–45 × 6–10 µm.
dark red, 1.2–2.2 cm.
constricted below mouth when dry;
exothecial cells long- to short-rectangular, 30–105 × 18–35 µm, walls firm, not collenchymatous;
annulus separating, 2–4-seriate, cell walls thin;
operculum acute, apiculate, or rostrate;
exostome teeth yellow-brown, external surface cross striolate basally, coarsely papillose distally, internal surface trabeculate;
endostome basal membrane high, segments not or narrowly perforate.
finely papillose.
Hygroamblystegium varium
Hygroamblystegium varium subsp. noterophilum
Subspecies 2 (2 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Subspecies noterophilum is morphologically characterized by its large size, broad, excurrent costa ending in a stout point, and partly 2-stratose lamina. This taxon is restricted to areas of oligotrophic, calcareous springs. The leaves of submerged stems are frequently quite different in shape from those of emergent stems and branches, suggesting that at least some of the morphological characteristics may be altered depending on water availability. Current phylogenetic analyses failed to demonstrate the genetic integrity of the taxon. The morphology of populations from calcareous springs is typically very different from that of terrestrial or subaquatic populations in many bryophyte species. For example, in Cratoneuron filicinum (Hedwig) Spruce, such expressions are so different that they were previously interpreted as Hygroamblystegium tenax var. spinifolium (Schimper) Jennings. Therefore, pending additional evidence, subsp. noterophilum is treated here as a subspecies of H. varium.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Plants small to moderately large; stems to 10 cm; costae narrower than 100 µm at base, to mid leaf, percurrent, or rarely short-excurrent; lamina 1-stratose. | subsp. varium |
1. Plants extremely large; stems to 15 cm; costae 110-140 µm wide at base, excurrent; lamina sometimes partially 2-stratose, especially at base near costa. | subsp. noterophilum |
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