38. Hedwigiaceae Schimper
Patricia M. Eckel
Plants medium-sized to large, coarse, in loose or dense wefts or mats, yellow-green, grayish green, blackish or reddish brown, olive brown, or opaque gray, dull, sometimes hoary with shining hairs distally. Stems creeping, remotely foliate, secondary stems creeping, erect-ascending, or loosely spreading, closely foliate, sparingly and irregularly branched to subpinnate, stoloniform or flagelliform-tapered, radiculose; sclerodermis cells in 2 or 3 rows, small, walls thick, cortical cells enlarged, central strand absent; paraphyllia absent; pseudoparaphyllia foliose, papillose. Stem and branch leaves erect to secund when dry, spreading when moist, ovate, broadly oblong- ovate, or ovate-lanceolate, strongly concave; base narrowing to insertion, broadly decurrent to abruptly concave-auriculate; margins erect, incurved, or revolute on one or both sides, mostly entire, denticulate to irregularly spinose-serrate at apex; apex acute, acuminate, or piliferous, concolorous, hyaline-white, or hyaline with pellucid tips, flat to subtubular, epilose, terminating in sharp or truncate point, or capillary hair; ecostate; alar cells differentiated, small or somewhat enlarged, often smooth, becoming papillose distally, walls thin or thick and porose, region in several marginal rows or in excavate auricles; laminal cells 1-stratose, papillose on both surfaces, walls usually thick, coarsely porose-sinuose; laminal cells near insertion short-rectangular, often smooth; mid basal cells concolorous to pigmented, papillae simple; medial and distal cells subquadrate, short-rectangular, or oblong-rhombic, 1-2(-3):1, 1- or multipapillose over lumina and/or walls, papillae simple or multifid; apical cells chlorophyllose or echlorophyllose, smooth to papillose, walls thick, even to strongly porose. Specialized asexual reproduction absent. Sexual condition autoicous or paroicous [rarely synoicous]; perigonia axillary on secondary stems and branches, gemmate; perichaetia terminal on main stems and branches, often appearing lateral by innovation, leaves erect, similar to vegetative leaves or larger, longer, ovate to narrowly ovate- lanceolate, margins entire, not to conspicuously ciliate, cilia sparse mid leaf, dense in apex, often longer than leaf length, hyaline. Vaginula with paraphyses few or many, long-filiform, yellow- hyaline. Seta single, very short or to beyond perichaetial leaves, straight, slender to stout, smooth, usually with sclerotic swelling below capsule neck. Capsule stegocarpous, erect, immersed to exserted, subglobose, obovoid, ovoid-cylindric, ellipsoid, fusiform, pyriform, or obpyriform, symmetric, contracted at base and below mouth, neck short, irregularly longitudinally sulcate when dry, mouth rigid, smooth, incurved, wide or narrow; stomata in neck, cryptoporic or phaneroporic; annulus absent; operculum planoconvex, sometimes subumbonate-apiculate, or 83 conic and rostrate; peristome absent. Calyptra conic-mitrate or cucullate, undivided at base or with several lobes, smooth, naked or pilose. Spores irregularly spheroid, flattened, with obscure triradiate mark on one side, brown.
Genera 4, species 32 (3 genera, 6 species in the flora): nearly worldwide.
The leaves of Hedwigiaceae are absolutely ecostate, strongly concave, decurrent-auriculate, and acute to abruptly acuminate, often with striking white apices or piliferous with long, pellucid apical hair-points. Laminal cells throughout the family are mostly subquadrate and arranged in longitudinal lines throughout the leaf, thick-walled, papillose, and collenchymatous, with patches of elongate cells in the leaf middle near the insertion, an area that is also usually more brightly colored than the rest of the leaf. Without peristomes, the family is difficult to place, but B. H. Allen (2002) gave a good synopsis of the speculative relationships. The family in the past has been placed among the pleurocarpous mosses because the leaves are ecostate, a trait rare among acrocarpous arthrodontous mosses (B. Goffinet and W. R. Buck 2004). However, the habit is acrocarpous, and the branching is sympodial (E. DeLuna, unpubl.) despite the plagiotropous habit typical of pleurocarpous mosses. All capsules have lax, flaccid cells in the neck region. When dry, the cells collapse making the capsule irregularly and variously pleated at the base; when moist, they are swollen, rendering the capsule urceolate, strongly fusiform or turbinate when dry, and globose, broadly oblong, cylindric-elliptic, or pyriform when moist. The fourth genus in the family, Hedwigidium Bruch & Schimper with two species is known from Old and New World tropics and temperate areas.
SELECTED REFERENCES De Luna, E. 1990. Protonemal development in the Hedwigiaceae (Musci), and its systematic significance. Syst. Bot. 15: 192-204. De Luna, E. 1995. The circumscription and phylogenetic relationships of the Hedwigiaceae (Musci). Syst. Bot. 20: 347-373.
