74. SYNTRICHIA          Plates 105, 106, 107, 108, 109, 110– 111.

Syntrichia Brid., J. Bot. (Schrader) 1(2): 299, 19 April 1801 (vide Sayre 1959). Type: Syntrichia ruralis (Hedw.) Web. & Mohr, lectotype fide Zander, Phytologia 65: 432, 1989.

Tortula subg. Syntrichia (Brid.) Chev., Fl. Gén. Env. Paris 2: 52, 1827.

Barbula subg. Syntrichia (Brid.) BSG, Bryol. Eur. 2:10, 1851 (fasc. 46–47 Consp. 2: III).

Tortula sect. Syntrichia (Brid.) Lam. & Cand., Syn. 100, 1806.

Tortula sect. Rurales De Not., Mem. R. Acc. Sc. Torino 40: 286, 1838. Type: Tortula ruralis (Hedw.) Gaetrn., Meyer & Scherb.

Barbula sect. Rurales BSG, Bryol. Eur. 2: 101, 1842 (fasc. 13–15 Mon. 39).

Barbula sect. Syntrichia (Brid.) C. Müll., Syn. 1: 632, 1849.

Barbula sect. Vallidens C. Müll., Linnaea 42: 347, 1879, nom. inval. Type: Barbula percarnosa C. Müll.

Barbula sect. Syntrichiae Lesq. & James, Man. N. Amer. Moss. 130, 1884, nom. illeg.

Barbula sect. Ruraliformes Kindb., Eur. N. Amer. Bryin. 2: 245, 1897, nom. illeg. incl. sect. prior. Type: Barbula ruralis Hedw.

Syntrichia sect. Eusyntrichia Moenk., Laubm. Eur. 306, 1927, nom. illeg.

            Found on rock, soil and bark on all continents, most commonly in temperate areas but also characteristic of dry climates.

            Syntrichia is segregated from Tortula s. lat. by the combination of red KOH reaction of the upper laminal cells, lack of narrowly elongate upper laminal marginal cells, the crescent-shaped transverse section of the stereid band, and the general lack of differentiated dorsal costal epidermal cells. This concept is essentially that of Kramer (1980, 1988), who emphasized the exposed dorsal stereid band (Pl. 105, f. 7, 15), not covered dorsally by parenchymatous or otherwise differentiated epidermal cells. Recently Ochyra (1992) supported this concept (Zander 1989) as “a natural group that deserves recognition as a genus of its own” with a series of new combinations appropriate for the Polish flora. Syntrichia is distinguished from Hennediella (likewise KOH red) by the leaves ligulate to spathulate or very seldom lanceolate, margins usually recurved and seldom dentate or bordered, upper laminal cells smaller and superficially strongly convex, costa commonly excurrent as an awn, almost always lacking a dorsal costal epidermis, stereid band semicircular to crescent-shaped, and sporophytes not in a reduction series within the genus.

            Note that in some few species (e.g. S. brandisii) a dorsal epidermis is very weakly differentiated (seen as somewhat wider lumens in costal transverse section), but these species are placed here rather than with Hennediella because of their recurved, unbordered margins and small upper laminal cells. Syntrichia costesii (Pl. 107, f. 17–19), like certain species of Hennediella, has an intramarginal border of differentiated cells, but those cells are isodiametric and the costa lacks a differentiated dorsal epidermis. The existence of a weakly differentiated dorsal epidermis in some species may indicate a derivation of Syntrichia from Bryoerythrophyllum, which differs, in traditional characters, in the presence of a second stereid band and usually narrower (broadly lanceolate to ligulate) leaves. Most cladograms in the phylogenetic analysis show Syntrichia and Bryoerythrophyllum to be quite distant. A few species, like S. laevipila (Pl. 109, f. 4–5), may occasionally and perhaps abnormally have one or two stereid or substereid cells present ventrally between the guide cells and the ventral epidermis as a tiny second stereid band, while in the type (isotype, NY) of S. rubra (Pl. 111, f. 5–8) and a second specimen seen (as Tortula rubra var. subantarctica, Campbell I., Sorensen 1946, isotype, NY), the ventral stereid band is of several stereid cells, the ventral epidermis is lacking, and superficially, the ventral surface of the costa is similar to the dorsal surface, being of superficially elongate, simply papillose cells. Syntrichia percarnosa (Pl. 109, f. 20–22) has much the same leaf morphology as Trichostomum crispulum, and the former species may well belong with that genus; the substereid cells of the costa are, however, arranged more like those of Syntrichia.

            Certain species of Didymodon sect. Vineales (KOH red) may lack a ventral stereid band, but have lanceolate leaves and narrowly rectangular basal cells. Bryoerythrophyllum and Mironia species are also KOH red and may have long-ligulate leaves, but the transverse section of the costa is reniform in section and the stem has a sclerodermis. Syntrichia geheebiaeopsis (Pl. 108, f. 13–17, cf. discussion by Lightowlers 1985a as Tortula) has many of the characters of Bryoerythrophyllum and Mironia, including broadly lanceolate, dentate leaves with a sheathing leaf base, small upper laminal cells with low, crowded papillae. It further differs from Syntrichia by the very narrowly rectangular basal cells. Bryoerythrophyllum and Mironia have semicircular to reniform costal sections, however, with usually two distinct stereid bands and a differentiated dorsal epidermis, but S. geheebiaeopsis has the typical costal morphology of Syntrichia: a nearly circular costal section, with a single stereid band and no differentiated dorsal epidermal cells. It mayprove to be a good genus in the Merceyoideae apparently having lost, like Streptopogon, the ventral stereid band.

            Syntrichia cavallii (Pl. 107, f. 7–12) is unusual in its strongly differentiated perichaetial leaves that are similar to those of S. papillosa (sect. Collotortula); it is, however, apparently related to S. percarnosa, instead. Syntrichia cavallii differs from Calyptopogon, in which perichaetial leaves are differentiated, in that propagula are lacking and the upper laminal papillae are multiplex. Willia also has strongly differentiated perichaetial leaves, but these are usually somewhat secund, and the sporophyte is distinctively reduced in length and complexity. Syntrichia cavallii is here placed in sect. Syntrichia, not sect. Collotortula, because of the lack of collenchymatous thickenings in the upper laminal cell walls. Eventually, perhaps, further study may require that a separate section or genus be devised for S. cavallii (see also discussion under Willia).

Syntrichia sect. Collotortula Zand., sect. nov. Type: Syntrichia andicola (Mont.) Zand.

A sectione typica cellulis laminalibus in regione mediana superna plerumque distincte in angulis incrassatis vel tumescentitrigonis, marginibus folii plerumque recurvis, papillis interdum simplicibus, propagulis si effectis clavatis vel ellipticis differt.

            Differs from the typical section by the following combination of characters: medial upper laminal cells usually somewhat thickened at the corners or even trigonous (i.e. with bulging knots), leaf margins usually recurved, papillae sometimes simple, and propagula when present clavate or elliptical. Examination of transverse leaf sections indicates that the interior upper laminal cell walls may have large, round central pores (staining helps define this) in at least some species (Syntrichia aculeata, S. amphidiacea, S. andicola (Pl. 106, f. 19), S. bogotensis, S. gemmascens, S. gromschii and S. papillosa), while in other species, including those of other sections of Syntrichia, the pores are absent or what appear to be interior pores are occasional, irregular and possibly artifacts. Features correlated with laminal cell collenchymatous thickenings are the upper leaf margin usually serrate and the stem central strand often lacking, but these are not unique characters. The section may not be sharply distinct from sect. Syntrichia because certain species of that section may have weakly thickened cell corners (appearing as bright triangular points of light under high magnification). The counterclockwise-twisted seta of Syntrichia papillosa commented upon by Dixon (1923) as unusual is not taxonomically significant, since long setae in the Pottiaceae are generally twisted clockwise below and counterclockwise above, and short setae are untwisted or merely twisted clockwise. The seta of S. papillosa (Pl. 109, f. 19—from a specimen misidentified as Tortula panduraefolia, Tasmania, Weymouth 2821, NY) is only about 5 µm in length. Species (some surely synonyms of S. andicola) belonging to sect. Collotortula include: S. aculeata, S. alpestris, S. amphidiacea (Pl. 106, f. 1–8), S. andicola (Pl. 106, f. 14–20), S. antarctica (possibly belongs here, but laminal cell walls are only weakly collenchymatous), S. bogotensis, S. cainii (Pl. 107, f. 5–6), S. ciliata, S. conferta, S. fontana (laminal cells flat superficially, as in Hennediella), S. gemmascens (Pl. 106, f. 18–21), S. goudotii, S. gromschii, S. mollis, S. papillosa (Pl. 109, f. 14–19), S. rivularis (Pl. 109, f. 20–23), S. robusta (Pl. 111, f. 1–4),  S. rubra (Pl. 111, f. 5–8), and S. subaristata. Curiously, S. rigescens has propagula (Pl. 110, f. 18–19) borne ventrally on the costa, as in sect. Collotortula, but is clearly in sect. Syntrichia near S. caninervis. Note also Syntrichia leucostega, not seen, for which ventral costal propagula are illustrated by Kramer (1988).

Syntrichia sect. Aesiotortula Zand., sect. nov. Type: S. pagorum (Milde) Amann.

A sectione typica plantis parvioribus quam congeneribus, foliis ligulatis vel spathulatis, marginibus omnino planis, papillis bifidis, propagulis si effectis foliaceis, in termino caulis vel in apicibus foliorum deciduis portatis, costa supra regione folii mediana perincrassata et in sectione transversalis semicircularibus differt.

            Differs from the typical section by the following combination of characters: plants rather small for the genus, leaves ligulate to spathulate, margins plane throughout, papillae bifid, and propagula when present leaf-like, borne terminally on the stem or as deciduous leaf apices. The costa is often very strongly thickened above midleaf and semicircular in transverse section. This group of species includes S. ammonsiana (Pl. 105, f. 12–16), S. baileyi, S. bartramii, S. chisosa (Pl. 107, f. 13–16), S. epilosa (Pl. 108, f. 1–9), S. pagorum (Pl. 109, f. 10–11), S. phaea (Pl. 109, f. 23–27) and S. pygmaea (Pl. 110, f. 10–16). Syntrichia papillosa, although here placed with sect. Collotortula because of the clearly trigonous upper laminal cells and clavate to spherical propagula, also has plane margins and a much thickened costa.

            Section Aesiotortula (as the “Tortula laevipila-Tortula pagorum-Gruppe”) was not dealt with by Kramer (1980), who viewed it as a complex requiring special study. Certain of the infraspecific taxa of S. laevipila may also belong here, but not var. laevipila (Pl. 109, f. 1–9) itself. Syntrichia pygmaea is only tentatively placed in this section; it is propaguliferous, however, by a deciduous leaf apex and has plane margins. On the other hand, species of similarly small stature in many genera have a tendency to lose or exhibit less distinctly some important characters, including recurvature of the lower margins. Syntrichia pygmaea is also unusual for its ventral leaf surface very narrowly grooved along the costa and ventral costal cells elongate, which may be an indication of a relationship with the Bryoerythrophylleae for this species. The upper laminal cells of the most highly derived of the species of sect. Aesiotortula are relatively large for the genus, generally 13–15 µm in diameter; species with upper laminal cells small (ca. 8–10 µm in diameter), such as S. bartramii and S. chisosa, are less distinctive. The cleistocarpous genus Phascopsis could be seen as having been derived from this section of Syntrichia, but is apparently a relict of a more primitive lineage (see Cladograms 13 and 14).

            The New World austral species Syntrichia epilosa is much the same as S. bartramii of western North America and maybe synonymous; a parallel southern South America and southwestern North America distribution is that of the austral Pseudocrossidium crinitum and its Arizona population previously known as Tortula aurea (see treatment of Pseudocrossidium).