Hedwigia

P. Beauvois

Mag. Encycl. 5: 304. 1804

Etymology: For Johann Hedwig, 1730 – 1799, German bryologist and physician
Treatment appears in FNA Volume 28. Treatment on page 84. Mentioned on page 85, 88, 90, 642.

Plants large, sordid yellow-green, rarely bright green, pale buff to red-brown with age, sometimes hoary distally. Stems with stoloniform-flagelliform branches absent. Leaves erect to subsecund and imbricate, not undulate-plicate, occasionally somewhat striolate when dry, 1.5–3 mm; margins recurved or sometimes plane in proximal 1/2–2/3, plane, erect, or incurved in acumen, in larger leaves closely and irregularly dentate to spinulose-dentate in apex; apex erect to patent when dry, wide-spreading and recurved or reflexed when moist, acute, acuminate, or subpiliferous, concolorous when muticous, or hyaline-white with pellucid tip, canaliculate-furrowed to tubular, papillose proximally, spinose-serrate medially, smooth apically; alar cells oblate, quadrate, or short-rectangular, smooth to simple-papillose, walls even to thick and porose, region concolorous or color similar to mid basal region, in several rows along margins; mid basal laminal cells long-rectangular, papillae 4–7, in 1 row, walls strongly thick, moderately to strongly porose, region strongly yellow- to red-orange across insertion or to 1/4–1/3(–1/2) leaf length; medial cells 1- or multipapillose on both surfaces, papillae simple or multifid, walls thick, moderately to coarsely and irregularly porose-sinuate; distal cells chlorophyllose and similar to medial cells, or echlorophyllose and differentiated, prorulose at distal cell ends, papillose; apical cells pellucid, less papillose. Sexual condition autoicous; perichaetial leaves to 4 mm, margins entire or ciliate distally. Vaginula with paraphyses few to many, smooth, occasionally papillose, often extending onto developing calyptra. Seta reddish brown, 0.5–0.9 mm, stout, hidden by perichaetial leaves. Capsule deeply immersed, brown proximally, shiny red-brown at mouth, turbinate-urceolate when dry, subglobose, short-ovoid, or obovoid when moist, 1 mm, longitudinally wrinkled to sharply sulcate when dry, smooth except for neck, mouth wide; stomata cryptoporic; operculum planoconvex, sometimes subumbonate-apiculate. Calyptra conic-mitrate, 0.5–0.9 mm, covering apex of capsule, pilose or naked. Spores 19–30 µm, finely to somewhat coarsely vermiculate-papillose.

Distribution

Nearly worldwide.

Discussion

Species 6 (3 in the flora).

Hedwigia in North America was until recently considered as a single species, with numerous varieties and forms (G. N. Jones 1933). Although a hair-point is often ascribed to species of Hedwigia, the acumen may be elongated but there is never a hairlike process as in Pseudobraunia. Long, multicellular cilia on leaf margins are rare among bryophytes (B. Goffinet et al. 2008), but are present on the perichaetial leaves in H. ciliata and H. stellata.

The type of Hedwigia integrifolia P. Beauvois was collected in North America. The name was used for a widespread species now considered Braunia imberbis (Smith) N. Dalton & D. G. Long. The type of H. integrifolia was examined by N. J. Dalton et al. (2012) and found unrelated to B. imberbis. Hedwigia integrifolia was synonymized with Hedwigidium imberbe (Smith) Bruch & Schimper by W. J. Hooker and T. Taylor (1818). Presently the application of the name H. integrifolia is awaiting further study, although G. N. Jones (1933) considered H. integrifolia a synonym of H. ciliata (B. H. Allen 2010).

Selected References

None.

Key

1 Medial and distal laminal cells with papillae (1-)2-4 per cell, simple, sessile, or low-stalked, variously branched; perichaetial leaf margins ciliate distally; apical laminal cell obtuse to truncate, multipapillose-coronate, short-rhomboidal, (40-)50-75(-80) µm. Hedwigia ciliata
1 Medial and distal laminal cells with papillae usually 1 per cell, stalked, strongly, irregularly branched; perichaetial leaf margins ciliate or entire distally; apical laminal cell sharply pointed, smooth or papillose, long-linear, (80-)120-175(-200) µm > 2
2 Leaf apices wide-spreading to squarrose when dry; laminal cells in hyaline area with some papillae large, spinose, among shorter papillae; papillae on abaxial leaf surface with branches of unequal lengths; perichaetial leaf margins long-ciliate distally. Hedwigia stellata
2 Leaf apices erect when dry; laminal cells in hyaline area with papillae low, simple, in lines; papillae on abaxial leaf surface with branches usually of equal lengths; perichaetial leaf margins entire. Hedwigia detonsa