BFNA Title: Pterobryaceae
Author: A. Newton, W. R. Buck
Date: June 2001
Edit Level: R
Version: 2

Bryophyte Flora of North America, Provisional Publication
Buffalo Museum of Science
1020 Humboldt Parkway
Buffalo, NY 14211 USA


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Angela Newton
version 2

Plants 0.2--3.0(--6.0) cm, creeping stolons becoming erect, inclined or horizontal to form simple or pinnately branched leafy stems, often with a basal stipe region; flagelliform branches frequent; dark or yellowish green. Stem cortex of orange-brown, thick-walled cells, central strand not differentiated; paraphyllia absent; pseudoparaphyllia filamentous, uniseriate, hyaline; rhizoids mostly restricted to stolons; axillary hairs 2--3 per axil, of 1--2 short brownish basal cells and 2--4 longer hyaline cells. Leaves on stolons scale-like, 0.2--1.25 mm, short-acute or long-acuminate, usually ecostate; in stipe region appressed, erect or recurved from a clasping base, triangular to ovate-acuminate, costa double or single, shorter in distal stem leaves; in stem region leaves erect to spreading or squarrose, lanceolate, ovate-acuminate or orbicular, 1.3--2.6 mm; margins plane, rarely revolute to apex, entire to serrulate distally; costa single to mid-leaf or percurrent, or short and double; cells at insertion dark yellow, thick-walled, porose and irregular; medial laminal cells sinuose, smooth or prorate, rarely with one or two papillae over the cell lumen, walls often porose; distal laminal cells shorter; alar cells little differentiated or rhombic to quadrate in several rows up margin, rarely oblate in many rows extending up margin in lower third of leaf; branch leaves concave, narrowly ovate-acuminate, smooth or weakly plicate, smaller or similar to distal stem leaves. Specialized asexual propagation frequent, clavate gemmae in clusters in leaf axils, reddish brown, uniseriate, of 4--12 quadrate or rectangular cells, thick-walled and verrucose. Sexual condition dioicous. Perigonia on stem and branches, bud-like, with a few scale-like leaves, uniseriate paraphyses and 5--10 antheridia. Perichaetia on stem and branches, urceolate; perichaetial leaves 8--12, the interior ovate-acuminate, abruptly narrowed to long erect awns; multiseriate paraphyses often present. Seta red-brown, 3.0--12.4 mm. Capsule erect, exserted, red-brown, ovate-cylindrical, narrowed to mouth, smooth; stomates absent; operculum rostrate from low, rounded or conic base, rostrum inclined. Peristome with prostome; exostome reduced, teeth 16, often in 8 irregular pairs, incurved when dry, erect when moist, lanceolate, often irregular, inserted below mouth, mostly smooth; endostome consisting of remnants adhering to back of exostome. Calyptra cucullate, fully or partially covering the capsule, with scattered archegonia and paraphyses or smooth, not plicate. Spores spherical, 20--35µm diameter, granulose, green.

Genera ca. 16, species ca. 200 in Pterobryaceae s.str. (3 genera, 4 species in the flora): tropical and subtropical regions worldwide.

The family is highly diverse, and has frequently been the depository of odd tropical taxa excluded from other families. The description above applies only to taxa in the flora area. Few features unite the family as currently circumscribed, and even these are not present in all taxa: tropical, primarily epiphytic habitats; a frondose habit frequently with a differentiated stipe, although this may only be apparent in juvenile plants; uniseriate filamentous pseudoparaphyllia (B. H. Allen 1987); no stomates; reduced peristomes, often with a prostome, and a highly reduced endostome.

The inclusion of Henicodium in the family is questionable on morphological grounds, since the presence of papillae centrally located over the lumen and a revolute leaf margin is otherwise not known in the family. However molecular studies indicate some affinity between Henicodium and Orthostichopsis (W. R. Buck et al. 2000), although Pterobryon, the type genus, is usually placed distantly from both these exemplars (A. E. Newton et al., in prep.). Henicodium is accepted here pending resolution of the family circumscription.

SELECTED REFERENCES Allen, B. H. 1987. On distinguishing Pterobryaceae and Meteoriaceae by means of pseudoparaphyllia. Bryol. Times 42: 1-3. Arzeni, C. B. 1954. The Pterobryaceae of the southern United States, Mexico, Central America and the West Indies. Amer. Midl. Naturalist. 52: 1--67. Buck, W. R. 1989. Henicodium replaces Leucodontopsis (Pterobryaceae). Bryologist 92: 534. Buck, W. R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82. Buck, W. R., B. Goffinet and A. J. Shaw. 2000. Testing morphological concepts of orders of pleurocarpous mosses (Bryophyta) using phylogenetic reconstructions based on trnL-trnF and rps4 sequences. Mol. Phylog. Evol. 16: 180-198. Newton, A. E. 1993. Phylogenetic systematics of the tropical moss genus Pireella (Pterobryaceae: Musci). Ph.D. Dissertation, Duke University, Durham, North Carolina.


1. Leaf margins revolute nearly to apex, cells in proximal third of leaf oblate in many rows up the margin, lamina cells with one or two papillae over the lumen       3. Henicodium

1. Leaf margins plane, cells in basal angles undifferentiated or rhombic-quadrate in several rows, lamina cells smooth or prorate.             

2. Plants simple or sparsely branched, leaves broadly ovate to orbicular, spreading to squarrose, costa variable on a single plant, double and short, or single, short or reaching to midleaf or above        1. Jaegerina

2. Plants simple or weakly and irregularly pinnate, leaves ovate acuminate, erect to spreading, costa single, percurrent or shortly excurrent  2. Pireella

1. JAEGERINA J. K. A. Müller, Linnaea 40: 273. 1876 • [for August Jaeger, 1842--1877, Swiss bryologist]

Jaegerinopsis V. F. Brotherus, Natürlichen Pflanzenfamilien 1(3):790. Leipzig 1906

Plants 1--5 cm, creeping stolons forming erect stems that are simple or sparsely branched above a very short stipe-like basal portion, shiny yellowish green. Stem leaves dense, not seriate, similar wet or dry, spreading to recurved or squarrose [erect], broad ovate-orbicular [ovate-lanceolate], 1.5--2.5 X 1.0--1.5 mm, concave, weakly plicate; apex acute, base not auriculate or decurrent; margins plane, entire to serrulate; costa short and double or single, reaching to mid-leaf or above, sometimes forked; medial laminal cells sinuose, 35--65 µm, smooth, walls porose; alar cells little differentiated. Branch leaves, if present, similar to stem leaves. [Seta 4--5 mm. Capsule cylindrical; operculum long-rostrate from a low conical base, rostrum inclined, blunt. Calyptra partially covering capsule, hairless, rough with projecting cell ends.]

Species 12 (1 in the flora); tropical and subtropical regions, se United States, Mexico, West Indies, Central America, n S. America, tropical Africa, Asia, Africa.

1. Jaegerina scariosa (Lorentz) Arzeni, American Midland Naturalist 52: 12. 1954

Meteorium scariosum Lorentz, Moostudien. p. 165. Leipzig. 1865; Jaegerinopsis scariosa (Lorentz) Brotherus; Jaegerinopsis squarrosa E. Britton

Plants 1--5 cm; not or rarely branched. Stem leaves spreading to recurved or squarrose, ovate-orbicular, 1--2 X 0.75--1.5 mm, apex acute; costa variable, from short and double to long and single to above mid-leaf; medial laminal cells sinuose, 33--60 X 2.5 µm, smooth; alar cells little differentiated, 4-8 small quadrate cells.

Sporophytes not known from flora region. Humid hardwood forests and hammocks, tree trunks, especially Magnolia grandiflora; 0-800 m; Fla., La.; Mexico; West Indies; Central America; n South America, tropical Africa.

The extreme variability of the costa in J. scariosa has resulted in a surplus of names for this species. Individual plants may have leaves with a weak or moderately strong single costa reaching to mid-leaf or above, sometimes forked above, or a short double costa, or a mere trace at the leaf base. The plant is readily recognized in the field, however, where it forms small tufts of erect stems on tree trunks. The leaves are glossy yellow and always broadly spreading to squarrose, giving the plants a distinctive appearance. Leucodon julaceus and species of Cryphaea occupy the same habitat, but are smaller and have the leaves appressed when dry, amongst other differences. Neither gametangia nor sporophytes are known for J. scariosa in the flora area.

2. PIREELLA Cardot, Rev. Bryol. 40: 17. 1913 • [for Louis Piré, 1827--1887, Belgian bryologist]

Plants 1--5 cm, creeping stolons forming erect stems that are simple or irregularly pinnate from a short or long stipe-like region, dull dark green to glossy yellowish green. Stem leaves dense, obscurely seriate; in basal stipe region appressed to erect, triangular-lanceolate, 0.5--1.7 mm; in distal region erect dry, spreading wet; broadly ovate-acuminate, 1.3--2.6 mm; concave, not plicate; base rounded, auriculate or decurrent; margin plane; costa single, short in proximal leaves, percurrent or shortly excurrent in distal leaves; medial laminal cells sinuose, prorate, firm-walled, porose; alar cells rhombic or quadrate, in small groups or extending up margin in a few rows. Branch leaves weakly or strongly seriate in five rows, spreading wet and dry; narrow ovate-acuminate, concave with flattened apex, not plicate; costa percurrent; medial laminal cells sinuose, distinctly prorate. Seta 5.4--12.4 mm. Capsule cylindrical; annulus not differentiated; operculum rostrate from a low rounded or conic base. Calyptra covering the capsule, hairy.

Species 13 (2 in the flora): se United States, Mexico, West Indies, Central America, n and c South America.

Pireella, with 13 species, is the largest genus of the Pterobryaceae in the Neotropics, and is composed of three distinct groups, two of which are not represented in the flora area, and are not covered by the description above. The two species in North America are rather similar and have frequently been misidentified in the past, but differ in the shape of the leaf base, the number, size and distribution of alar cells, the shape and stance of the leaves, and the branching pattern. The leaf-base characters are most useful, but can only be distinguished reliably on the distal stipe or stem leaves. C. B. Arzeni (1954) clarified the distinction between these species, but misidentifications have continued. This may in part be attributed to misidentified material in herbaria, in particular to exsiccati issued by W. Bauer and by A. J. Grout, and material annotated by C. B. Arzeni and by E. Britton. The distributions of the species differ in the flora area, but elsewhere their ranges overlap.



1. Plants mostly weakly and irregularly pinnate, branch leaves weakly seriate; base of stem and upper stipe leaves rounded to auriculate, with a small area of shorter, rhombic alar cells not reaching the leaf margin 1. Pireella pohlii

1. Plants mostly simple, sometimes weakly pinnate, branch leaves strongly seriate, base of stem and upper stipe leaves weakly decurrent, with several rows of quadrate alar cells extending up the leaf margin         2. Pireella cymbifolia

1. Pireella pohlii (Schwägrichen) Cardot, Rev. Bryol. 40: 18. 1913

Leucodon pohlii Schwaegrichen, Spec. Musc. Frond. Suppl. 3(1): 232. 1828; Pireella ludoviciae (J. K. A. Müller) Grout

Plants 0.5--10 cm; branching irregularly pinnate. Stem leaves in short basal stipe region ovate-triangular; distal leaves erect from clasping base, ovate-acuminate, 0.6--2. 5 X 0.4--1.1 mm; base not decurrent, weakly to strongly rounded, often auriculate; apex narrowly acuminate; costa filling awl-like apex in distal leaves; medial laminal cells sinuose, 18-64 X 2.5 µm; alar cells variable, indistinct or (especially in auriculate plants) with a few rows of irregular-quadrate cells not reaching leaf margin. Branch leaves in five obscure spiralling rows; ovate-acuminate, 0.9--1.7 X 0.3--0.6 mm; strongly concave with long narrow flat acuminate apex; medial laminal cells 18--62 X 2.5 µm, weakly to strongly prorate, tips of prorae with low conical papillae. Seta 5--12 mm. Capsule cylindrical, 1.5--2.5 X 1 mm. Calyptra cucullate, covering capsules at maturity, with scattered biseriate hairs. Spores spherical or ovoid, 23--37 X 18--35 µm.

Capsules mature in late winter (Feb.--Mar.); sporophytes known from only one site in Florida in the flora area. Dry, mesic or boggy hardwood forests and hammocks, deep wooded ravines, mixed woodland and dry sandy scrub, tree buttresses and trunks from base to 20 m, branches, also palms, logs, rocks; 0--1900 m; Ala., Fla., La., Miss., c and s Mexico, West Indies, Central America, South America (to Paraguay and s Brazil).

Few other mosses in the region are likely to be confused with P. pohlii, other than P. cymbifolia. Plants of P. pohlii are usually irregularly pinnate, but may be simple if depauperate. The bases of stipe and stem leaves are variously rounded to almost auriculate, the alar cells are sub-quadrate or rhombic and few in number, and do not reach the margin. The species is found from central and northern Florida to Louisiana.


2. Pireella cymbifolia (Sullivant) Cardot, Rev. Bryol. 40: 17. 1913

Pilotrichum cymbifolium Sullivant in A. Gray, Manual (ed. 2.) 681. 1856

Plants 0.2--2.5 cm, unbranched or sparsely and irregularly pinnate. Stem leaves in basal stipe region broad ovate-triangular, often very small for a large proportion of the stipe, 0.5 X 0.3 mm; distal leaves erect from clasping base, ovate-lanceolate, 1.8 X 0.9 mm; base decurrent, not rounded or auriculate; apex broadly acuminate; costa percurrent in distal leaves, medial lamina cells sinuose, 16--46 X 2.5 µm; alar cells in 7--14 rows of 2--23 quadrate or short rectangular cells 9--16 X 3--9 µm, running into decurrent wing and up leaf margin. Branch leaves in five distinct spiralling rows; ovate-acuminate, 1.1--1.7 X 0.3--0.6 mm, strongly concave with short broad flat acuminate apex; medial laminal cells 16--46 X 2.5 µm, strongly prorate, tips of prorae with low conical papillae. [Seta 5--9 mm. Capsule cylindrical, 1.8--2.7 X 0.9 mm. Calyptra cucullate, covering capsules at maturity, with scattered biseriate hairs. Spores spherical or ovoid, 30--41 X 28--35 µm.]

Sporophytes not known from flora area. Dry evergreen forest, lowland deciduous forest and hammocks, occasionally flooded palm woodland, and disturbed woodlands, on trees and tree roots, bushes, decaying wood, limestone and sandstone; 0--700 m; Fla.; s Mexico, West Indies, Central America, South America (to offshore islands in s Brazil.)

Plants of P. cymbifolia are usually small and scarcely branched, although well-grown plants (for example in the Florida Keys) may be larger and irregularly pinnate. The leaf bases are decurrent, with several rows of quadrate alar cells extending up the margin. P. cymbifolia is restricted to southern Florida. Superficially, Pireella cymbifolium may resemble Henicodium, but under the microscope the more extensive area of oblate cells in the leaf base and the distinctly plicate leaves in the latter species should prevent confusion.

3. Henicodium (J. K. A. Müller) Kindberg, Enum. Bryin. Exot. 16. 1888

William R. Buck

Hypnum sect. Henicodium J. K. A. Müller, Linnaea 39: 470. 1875; Leucodontopsis Renauld & Cardot, "Leucodoniopsis"

Plants medium-sized, bright- to yellow-green to bronze; creeping stolons turning away from substrate to form erect stems that are not or little branched. Stem leaves dense, not seriate, appressed when dry, spreading when moist, oblong-lanceolate to oblong-ovate, concave, plicate, broadly and gradually acuminate; base somewhat decurrent; margins revolute from just below apex to mid-alar region; costa single, ending about 2/3 the leaf length, often obscured, especially above, by plicae; laminal cells linear-flexuose, 1-papillose, firm-walled, ± porose; alar cells well differentiated in large, conspicuous areas, oblate, collenchymatous. Seta elongate, ca. 6 mm. Capsule well exserted, short-cylindric; annulus and operculum not seen. Calyptra not known.

Species probably 1 (1 in flora); North America, West Indies, Central America, South America, Africa, Asia.

Henicodium is distinguished by mostly unbranched, erect stems with revolute-margined leaves. The leaf cells are 1-papillose (individual leaves may sometimes be smooth) and the costa ends well below the leaf apex. Gemmae are regularly produced on older stems in large clusters in distal leaf axils.

SELECTED REFERENCES Buck, W. R. 1989. Henicodium replaces Leucodontopsis (Pterobryaceae). Bryologist 92: 534. Buck, W. R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1--400.

3. Henicodium geniculatum (Mitten) W. R. Buck, Bryologist 92: 534. 1989

Leucodon geniculata Mitten, J. Linn. Soc., Bot. 12: 409. 1869; Leucodontopsis floridana (Austin) E. Britton; Leucodontopsis geniculata (Mitten) H. A. Crum & Steere

Plants medium-sized to slender, mostly 1--2 cm; erect stems not or rarely branched. Stem leaves appressed when dry, spreading when moist, oblong-lanceolate to oblong-ovate, 1.2--2.0 × 0.25--0.88 mm, apex gradually broadly acuminate or often appearing ± abruptly so because of subapical recurved margins; median laminal cells linear-flexuose, 42--71 × 4 _¼m, 1-papillose, rarely smooth; alar cells in 7--15 rows and extending up the margins by 25--50 cells, oblate, collenchymatous. Sporophytes not known from the flora region.

In ± open, mesic to dry forests, branches or less often tree trunks, frequently in, but rarely collected from, the canopy; near sea level in the floral area (to above 1000 m in South America); Fla.; Mexico; West Indies; Central America; South America; Africa; se Asia.

Henicodium geniculatum has mostly simple, erect secondary stems with 1-costate leaves. The margins are recurved nearly throughout and the cells are 1-papillose. The species may be distinguished from various Pireella species by leaves appressed when dry and spreading when moist (rather than little altered when dry), and leaf cells papillose over the lumina (rather than smooth or prorulose). Henicodium seems most often confused with poorly developed specimens of Pseudocryphaea domingensis. However, that species has a percurrent costa, leaf cells much wider and usually smooth, and no axillary gemmae but, usually, conspicuous flagellate branches.

Version History for Pterobryaceae:

Version 2: June 2001

Version 1: May, 2001