Timmia norvegica

Plants with deciduous, longer distal leaves with a less well-developed sheath. Leaf apex acute or acuminate; costae ending a few cells below apex or excurrent; sheath clear in the distal leaves, orange-brown to reddish black in the proximal leaves; limb green, pellucid; limb-sheath transition gradual; limb margins coarsely dentate in distal 1/3–1/2, slightly toothed, crenulate or ± entire proximally; limb lamina cells 6–16(–18) × 6–14 µm, with tall rounded mamillae on the adaxial surface, abaxial surface smooth; sheath lamina cells with (0–)1–6(–8) large round, verrucose papillae over abaxial surface of the lumen; cells at leaf insertion abruptly differentiated into 1 to a few rows of fragile, hyaline cells; limb costa papillose on abaxial surface, or toothed near the apex, adaxial cells with tall bottle-shaped mamillae. Sexual condition dioicous; perichaetial leaves longer and more evenly tapering than stem leaves, sheath poorly developed. Calyptra unknown. Capsule non-plicate; exothecial cells with extremely sinuose walls; stomata on neck and proximal urn; endostome cilia with numerous short blunt appendiculations on the interior surfaces.

Distribution

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North America, Eurasia, Atlantic Islands (Iceland), Pacific Islands (New Zealand).

Discussion

Varieties 2 (2 in the flora).

Timmia norvegica is related to T. sibirica, with which it shares the important character of fragile leaf bases; however, the papillosity of the limb in T. sibirica is a strongly differentiating character. Timmia norvegica differs from T. austriaca and T. megapolitana by having fragile leaf bases, heterophyllous leaves, and less well delimited leaf sheaths.

Selected References

None.

Lower Taxa

Timmia norvegica var. excurrens, Timmia norvegica var. norvegica

Key

1	Leaves 3-8(-12) mm, 0.8-1.1 mm wide at mid-limb; cells of mid-limb lamina (8-)9-16(-18) × (8-)9-14 µm; base of costa dark; never with loose clusters of linear leaves at stem tips	Timmia norvegica var. norvegica
1	Leaves 2-6 mm, 0.5-0.6 mm wide at mid-limb; cells of mid-limb lamina 6-10(-11) × 6-9(-10) µm; base of costa pale; stem tips often with loose deciduous clusters of almost linear leaves	Timmia norvegica var. excurrens