BFNA Title: Homomallium
Author: S. Newmaster
Date: February 6, 2010
Edit Level: R
Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden

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XXX.  HOMOMALLIUM (Schimper) Loeske, Hedwigia 46: 314. 1907 * [Greek homo, similar, like, and mallos, a lock of wool, thus bending or curving to one side, alluding to the leaves slightly and uniformly curved]


                                                                                                                    S. G. Newmaster


Hypnum  subgen. Homomallium Schimper, Syn. Musc. Eur., 616. 1860


Plants medium sized, 2--3 cm, irregularly branched, in dense, flat mats tightly appressed to substrate; pseudoparaphyllia few, foliose; axillary hairs sparse, 1--3-celled.  Stems prostrate, branches short; without hyalodermis or central strand, epidermal cells small and thick-walled.  Stem and branch leaves similar, erect-spreading or homomallous, concave, smooth, oblong-ovate, abruptly acuminate, non-decurrent, 0.8--1.3(--1.5) mm; margins plane, entire or serrulate in upper half; costa short and double or lacking; distal cells short, rhomboidal, 15--40 × 3.5--7 \um, smooth or papillose at back, moderately thick-walled, alar cells differentiated quadrate-rectangular in numerous rows.  Specialized asexual reproduction by dense clusters of short brood branches.  Sexual condition autoicous.  Perichaetial leaves oblong, acuminate, erect.  Seta 5--16 mm, single, elongate, smooth, flexuose, yellow-orange to red or purple.  Capsule 0.9--1.7 mm, inclined to horizontal, asymmetric, oblong-cylindric, arcuate, contracted below mouth, stomata restricted to base of urn; annulus 1-2 rows of large, deciduous cells; operculum 1.5--2 mm, convex-conic, apiculate to short-rostrate; exostome yellow or orange, cross-striolate basally, papillose distally, trabeculate; endostome hyaline, papillose, keeled, with distinct basal membrane, cilia 1--2, nodulose.  Calyptra naked.  Spores yellow to yellow-brown, minutely papillose, 10--20 \um.


Species 13 (3 in the flora): North America, Asia, Australia.


Homomallium is a medium-sized moss that lacks the characteristic secund leaves and longer cells found in other hypnaceous mosses. The genus is distinguished from other closely related genera by its short leaves with smooth, shortly rhomboidal distal leaf cells, numerous quadrate alar cells and inclined-horizontal capsules with a well-developed peristome. Homomallium sharpii, not included, here may be found in the area of the flora north of Mexico (see note under Homomallium adnatum).


SELECTED REFERENCES  Ando, H. 1973. Studies on the genus Hypnum Hedw. (II). J. Sci. Hiroshima Univ. (Ser. B, div. 2) 14: 165--207.  Ando, H. 1976. Studies on the genus Hypnum Hedw. (III). J. Sci. Hiroshima Univ. (Ser. B, div. 2) 16: 1--46. Ando, H. 1986. Studies on the genus Hypnum Hedw. (IV). Hikobia 9: 467--484. Ando, H. 1987. Studies on the genus Hypnum Hedw. (V). Hikobia 10: 43--54. Ando, H. and M. Higuchi. 1983. Homomallium sharpii, a new moss species from Mexico. Bryologist 86: 374--377. Crum, H. A. and L. E. Anderson. 1981. Mosses of Eastern North America. Vol. 2. New York.


1. Leaves spreading, not or only slightly homomallous, not falcate-secund; broadly short-  

acuminate…………………………………………...... 1.  Homomallium adnatum

1.  Leaves erect to spreading, homomallous to falcate-secund; slenderly-acuminate.

2.  Leaves subulate, medial leaf cells thin-walled; seta reddish brown……………………………..….………. 2.  Homomallium incurvatum

2.  Leaves not subulate, medial leaf cells thick-walled; seta yellowish orange……………………………………….... 3.  Homomallium mexicanum



1.  Homomallium adnatum (Hedwig) Brotherus, Natürl. Pflanzenfam. 1(3): 1027. 1908


Hypnum adnatum Hedwig, Sp. Musc. Frond. 248, plate 64, figs. 5--10. 1801


Stems irregularly branched, dark green or yellowish-brown, branches straight, 2--3 cm.  Leaves 0.5--1 mm, erect or slightly homomallous, abruptly short-acuminate, margins erect, entire, distal cells smooth, short, rhomboidal, 15--25 x 3.5--4.5 \um, alar cells thick walled, quadrate, extending 1/3 up the leaf at the margin.  Seta 5--15 mm, yellow-orange to red or purple.  Capsule 0.9--1.5 mm, yellow to reddish-brown; endostome segments not perforate.  Spores smooth to minutely papillose, 11--12 \um.


Capsules mature summer. Common on boulders (limestone or sandstone), moist areas such as streams or shaded ravines, occasionally on the base of deciduous trees, exposed roots near streams or rivers; N.B., N.S., Ont., Que.; Ala., Ariz., Ark., Colo., Del., Ga., Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Minn., Mo., Nebr., N.J., N.Y., N.C., N.Dak., Ohio, Okla., Pa., Tenn., Tex., Va., W.Va., Wis.; Asia.


Homomallium adnatum is found throughout eastern North America. Occasionally this species produces dense clusters of short brood branches as in Platygyrium repens, a corticolous species distinguished by its erect capsules, reflexed leaf margins and longer leaf cells. Although Hypnum cupressiforme is somewhat similar, it is distinguished by its longer leaves and alar cells that are restricted to the bottom 1/4 of the leaf margins. Homomallium sharpii is a similar species found in Mexico in comparable habitats, and has smaller branches (1 cm), differentiated stem and branch leaves, longer medial cells (more than 30 \um) and alar cells in small triangular groups. 



2.  Homomallium incurvatum (Schrader ex Bridel) Loeske, Hedwigia 46: 314. 1907


Hypnum incurvatum Schrader ex Bridel, Musc. Recent. 2(2): 119. 1801


Stems irregularly pinnate, glossy green or yellowish brown, branches straight, 2--2.5 cm.  Leaves 0.8--1.3 mm, homomallous with terminal leaves slightly secund, abruptly slenderly acuminate, subulate, margins erect, entire or finely dentate, distal cells smooth, linear, rhomboidal, 25--40 x 4--7 \um, alar cells thin-walled, quadrate, extending 1/3 up the leaf at the margin.  Seta 5--15 mm, reddish brown.  Capsule 1--1.5 mm, reddish brown.  Spores finely papillose, 10--12 \um.


Capsules mature summer. Calcareous rocks in forests, rarely on deciduous trees; Ala., Ariz., Ky., W.Va.; Europe; Asia; Australia.


H. A. Crum and L. E. Anderson (1981) questioned the presence of Homomallium incurvatum in North America as no voucher collections were available at the time of publication of Mosses of Eastern North America.  Since then, specimens have been collected in four states (Ala., Ariz., Ky., W.Va). This is an uncommon species similar in appearance to species of the genus Pylaisiella by the homomallous, lanceolate leaves with similar cell morphology, but Pylaisiella is larger with erect, symmetric capsules.


3.  Homomallium mexicanum Cardot, Rev. Bryol. 37: 53. 1910


Stems irregularly pinnate, green or yellowish-green, branches curved at tips, 2--2.5 cm.  Leaves 0.8--1.3(--1.5) mm, homomallous, abruptly slender acuminate, margins reflexed at base, entire or serrulate at apex, distal cells smooth, short, rhomboidal, 25--35 × 4--7 \um, alar cells thick-walled, quadrate-rectangular, extending 1/4--1/3 up the leaf at the margin.  Seta 10--16 mm, yellowish orange.  Capsule 1--1.7 mm, yellowish to reddish brown.  Spores faintly papillose, 11--20 \um.


Capsules mature summer.  Bark or soil at the base of trees. Occasionally on boulders in deciduous forests; Ariz., Colo., Kans., N.Mex., Tex.; Mexico; Asia; Australia.


Homomallium mexicanum is a largely subtropical species that appears more robust than the other two species because of its larger and more spreading leaves.


1. Leaves to 1.3 mm, not imbricate, ovate-lanceolate, narrowly acuminate, usually denticulate distally . . . 3a. Homomallium mexicanum var. mexicanum

1. Leaves to 1.5 mm, closely imbricate, broadly ovate, short-acuminate, entire . . . 3b. Homomallium mexicanum var. latifolium


3a. Homomallium mexicanum var. mexicanum


Leaves to 1.3 mm, loosely investing the stem, ovate-lanceolate, slightly concave, narrowly acuminate, usually denticulate distally, alar cells restricted to the proximal 1/4 of the leaf margins.


Bark or soil at base of trees, occasionally boulders; Ariz., Colo., Kans., Nev., N.Mex., Tex.; Mexico; Asia; Australia.


3b. Homomallium mexicanum var. latifolium Cardot, Rev. Bryol. 37: 54. 1910


Leaves to 1.5 mm, closely imbricate, broadly ovate, very concave, short-acuminate, entire, alar cells extending 1/3 up the leaf at the margin.


Cliffs, bed of stream; Ariz., N.Mex., Tex.; Mexico.  


Homomallium mexicanum var latifolium Cardot, has larger (to 1.5 mm), closely imbricate leaves that are broadly ovate, short-acuminate and entire.