Timmia norvegica
Öfvers. Kongl. Vetensk.-Akad. Förh. 19: 364. 1862,.
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
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.
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 |