Plants acrocarpous or cladocarpous
, small to large, usually olivaceous
to blackish green, growing in rigid
, tufts, mats or patches. Stems erect
, or prostrate
, dichotomously to irregularly branched. Leaves erect and tightly appressed
when dry, erect-spreading to patent
when wet, lanceolate to ovate-lanceolate, less often ovate
, oblong-ovate, linear
, or lingulate
, to broadly concave
or sometimes longitudinally plicate
, rarely with adaxial
lamellae (Indusiella), margins
, or variously recurved or revolute
, mostly entire, 1- to multistratose, acuminate, acute to rounded-obtuse, typically with a hyaline
, sometimes muticous
, costa single, rarely spurred
distally (Codriophorus and Niphotrichum), usually strong
to excurrent, rarely subpercurrent, typically with one stereid
, distal lamina 1-2(-4) -stratose; basal cells
, rarely oblate
, straight, sinuose, or nodulose
, basal juxtacostal and marginal
regions usually differentiated, alar cells
undifferentiated or hyaline; mid leaf cells
quadrate to elongate, commonly sinuose or sinuose-nodulose, usually thick-walled. Perichaetia terminal
of stems or lateral
branches; perichaetial leaves differentiated or not. Seta short to long, smooth or rarely papillose
. Capsule usually erect, usually ovoid
, cylindrical or cupulate
or rarely strongly ventricose
at the base
, smooth or sulcate
; annulus present or absent, often compound
, deciduous or persistent
; operculum mammillate
to long-rostrate, sometimes attached to the columella after dehiscence (most Schistidium) ; peristome present, seldom rudimentary
or absent, consisting of 16 teeth, lanceolate to linear, entire, perforated or cribrose, variously split into 2 or 3 unequal prongs or divided
nearly to the base into two filiform
segments, smooth or variously ornamented. Calyptra small to large, covering only the operculum to half or more of the capsule, cucullate
, mitrate, or mitrate-campanulate, smooth or plicate, naked, sometimes papillose, slightly to distinctly lacerated or deeply lobed
at the base. Spores globose
, smooth or papillose.
Genera ca. 11, species ca. 325 (9 genera, 109 species in the flora ) : worldwide.
Most species in the Grimmiaceae are xerophytic and colonizers of bare, usually dry and exposed rocks and stones , forming predominantly dark green to blackish cushions or tufts. However, some species occur on wet or damp rocks along watercourses and lakes or in seepage sites. They rarely inhabit soil and only a few species are epiphytes.
The Grimmiaceae is classically distinguished by quadrate to short-rectangular mid leaf cells typically sinuose to nodulose and thick-walled, and leaves usually awned , often with the awns long and toothed or papillose. There is a wide range of variation . While awns are present in most species, length varies from a short, translucent apiculus to exceeding the length of the lamina. Awns can be flat or terete , smooth or denticulate , spinose or papillose, and long-decurrent or not. Similarly, mid leaf cells range from oblate to long-rectangular and sinuose to almost straight. The range of variation in these characters makes it difficult to describe this family in simple and unequivocal terms .
The generic classification within the Grimmiaceae has long been a subject of controversy. In traditional treatments the family is considered to include the two largest genera, Grimmia and Racomitrium, with several peripheral, mostly mono- or oligotypic genera, including Aligrimmia R. S. Williams, Coscinodon, Coscinodontella R. S. Williams, Indusiella, Jaffueliobryum, and Leucoperichaetium Magill. A number of segregates have been split from the large and heterogeneous Grimmia, namely Dryptodon Bridel, Guembelia Hampe, Hydrogrimmia (I. Hagen) Loeske, Orthogrimmia (Schimper) Ochyra & Zarnoweic, Schistidium, and Streptocolea I. Hagen. In this treatment, only Schistidium is accepted. Racomitrium has been divided into four sharply delimited genera and the group is recognized at the subfamily level.
R. Ochyra et al. (2003) used two peristome types to divide Grimmiaceae into two subfamilies, Grimmioideae and Racomitrioideae. The Schistidium-type peristome defines the Grimmioideae. This peristome has lanceolate teeth that are entire or perforate and distally usually split into two or three unequal prongs that are smooth to ornamented. They have a distinctly thick and trabeculate abaxial side and a thin adaxial side. There is no basal membrane . In the Racomitrium-type peristome, which defines the Racomitrioideae, the teeth are linear and divided nearly to the base into two filiform branches. The teeth are equally thickened and less prominently trabeculate on both adaxial and abaxial sides. They usually arise from a low, basal membrane and often have a prostome .
Plants medium-sized to large, coarse
, usually hoary
, grayish, brownish or yellowish green, yellow or yellow- to blackish brown. Stems mostly pinnately branched, with many short, lateral
. Leaves erect
to slightly secund
when dry, loosely erect to erect-spreading or spreading-recurved when wet, narrowly ovate- to linear-lanceolate; margins
1-stratose, recurved to revolute
, entire proximally, coarsely dentate
along the hyaline
; apices gradually tapering to a long, slender, hyaline acumen; awns
, erose-dentate, long-decurrent, with the decurrencies flat or ruffled; costa percurrent
, in transverse
2-stratose, becoming 3-stratose in the proximal
1-stratose, sinuose, dull
, distinctly papillose with large, flat papillae covering the longitudinal
walls and almost the whole of the lumina except for a narrow central groove
; basal marginal
laminal cells long-rectangular, forming 1(-2) -seriate band
, consisting of to 30 rectangular, translucent
, not sinuose cells; alar cells
not differentiated; medial
cells long-rectangular; distal cells short-rectangular. Inner perichaetial leaves hyaline, oblong
, oblong-lanceolate to elliptical
, abruptly constricted
into a short, smooth
or weakly papillose awn. Seta single or often 2-3 per perichaetium
when dry, strongly papillose. Capsule straight, ovoid
to ovoid-cylindric, somewhat ventricose
in the base
; annulus revoluble
, 2-4-seriate; operculum long-rostrate; peristome teeth, long, reddish brown, split nearly to the base into 2 filiform
, strongly papillose branches. Calyptra conic-mitrate to cucullate
, naked. Spores spherical
yellow, finely roughened.
Species 3: North America, Central America, South America, Europe, Asia, South Africa, Atlantic Islands, Indian Ocean Islands, Pacific Islands, Australia, Antarctica.
Traditionally, Racomitrium has been considered as a homogeneous genus characterized by its laminal cells having thick and strongly sinuose to nodulose longitudinal cell walls. This characteristic leaf areolation was typically coupled with a peristome of linear teeth arising from a low or high basal membrane and divided nearly to the base into two filiform, somewhat paired segments that are equally thickened and less prominently trabeculate on both external and internal sides. In addition, the genus was characterized by the consistent lack of a central strand, usual presence of the prostome , sinuose-walled epidermal cells of the vaginula, and cladocarpous sexual condition. This combination of characters made Racomitrium readily recognizable. Revisionary studies of the genus showed that in its traditional circumscription it was an artificial, heterogeneous taxon and, as a result, it has been recently split into four genera, Racomitrium in the narrow sense, Codriophorus, Niphotrichum, and Bucklandiella. Racomitrium in the narrow sense is characterized by: distinctly papillose setae twisted to the left; long, hyaline, strongly papillose awns that are long-decurrent and erose-dentate; large, flat papillae with small secondary papillae densely covering the longitudinal cell walls and almost the whole lumina except for a narrow groove in the middle ; peristome teeth divided to the base into 2(-3) filiform branches; and capsules slightly ventricose at the base. The papillosity of the setae is a unique feature of this genus, and is unknown in other acrocarpous mosses. That character, the unusual shape of the awns, and the ventricose capsule make the narrowly conceived Racomitrium readily distinguishable from its segregates .
- Whittaker & Margulis,1978
- Haeckel, 1866
- Cavalier-Smith, 1981
- A. Braun, in Ascherson, 1860
- (Linnaeus, 1753) Cavalier-Smith, 1998
- Cavalier-Smith, 1998
- Order: Grimmiales ()
- Superorder: Haplolepideae ()
- Subclass: Dicranidae ()
- Class: Bryopsida () - - Mosses
- Infraphylum: Bryatae () - Cavalier-Smith, 1998
- Subphylum: Musci () - (Linnaeus, 1753) Cavalier-Smith, 1998
- Phylum: Bryophyta () - A. Braun, in Ascherson, 1860 - Mosses
- Subkingdom: Viridaeplantae () - Cavalier-Smith, 1981
- Kingdom: Plantae () - Haeckel, 1866 - Plants
Status: Accepted Name
Last scrutiny: 19-Jul-2004
Members of the genus Racomitrium
ZipcodeZoo has pages for 27 species, subspecies, varieties, forms, and cultivars in this genus:
R. aciculare (Racomitrium Moss) · R. affine (Racomitrium Moss) · R. aquaticum (Aquatic Racomitrium Moss) · R. brevipes (Racomitrium Moss) · R. brevisetum (Racomitrium Moss) · R. canescens (Plants) · R. canescens var. canescens (Plants) · R. canescens var. latifolium C.Jens. (Plants) · R. depressum (Racomitrium Moss) · R. elongatum (Elongate Racomitrium Moss) · R. ericoides (Racomitrium Moss) · R. fasciculare (Racomitrium Moss) · R. heterostichum (Racomitrium Moss) · R. lanuginosum (Racomitrium Moss) · R. lanuginosum lanuginosum (Racomitrium Moss) · R. lawtonae (Lawton's Racomitrium Moss) · R. macounii (Macoun's Racomitrium Moss) · R. microcarpon (Racomitrium Moss) · R. muticum (Racomitrium Moss) · R. obesum (Racomitrium Moss) · R. occidentale (Western Racomitrium Moss) · R. pacificum (Pacific Racomitrium Moss) · R. panschii (Pansch's Racomitrium Moss) · R. pygmaeum (Pygmy Racomitrium Moss) · R. sudeticum (Racomitrium Moss) · R. varium (Racomitrium Moss) · R. venustum (Racomitrium Moss)
- Search for Pictures: images.google.com
- Search for Scholarly Articles: Google Scholar
- Search using Scientific Name and Vernacular Names: All the Web | AltaVista Canada | AltaVista | Excite | Google | HotBot | Lycos
- Search using Specialized Databases: GenBank | Medline | Scirus | CISTI/CAL | Agricola Periodicals | Agricola Books
- Churchill, S. P. 1981. A phylogenetic analysis, classification and synopsis of the genera of the Grimmiaceae (Musci). Advances Cladist. 1: 127-144.
- Jones, G. N. 1933. Grimmiaceae. In: A. J. Grout. Moss Flora of North America, North of Mexico. 3 vols. in 12 parts. Newfane, Vt. and New York. Vol. 2, pp. 1-60.
- Tallis, J. H. 1964. Growth studies on Rhacomitrium lanuginosum. Bryologist 67: 417-422.
- Tallis, J. H. 1959. Studies in the biology and ecology of Rhacomitrium lanuginosum Brid. J. Ecol. 47: 325-350.
- Vitt, D. H. and C. Marsh. 1988. Population variation and phytogeography of Racomitrium lanuginosum and R. pruinosum. Beih. Nova Hedwigia 90: 235-260.
- Bisby, F.A., Y.R. Roskov, M.A. Ruggiero, T.M. Orrell, L.E. Paglinawan, P.W. Brewer, N. Bailly, J. van Hertum, eds (2007). Species 2000 & ITIS Catalogue of Life: 2007 Annual Checklist. Species 2000: Reading, U.K.
- Brands, S.J. (comp.) 1989-present. The Taxonomicon. Universal Taxonomic Services, Zwaag, The Netherlands. Accessed January 15, 2012.
- Global Biodiversity Information Facility. Accessed February 27, 2008. http://www.gbif.org Mediated distribution data from 2 providers.
- MOST: Moss TROPICOS Database. Release date: July 19, 2004
- Moss TROPICOS: the World Checklist of Mosses
- Moss TROPICOS DatabaseJul 1, 2004.
- Ruggiero M., Gordon D., Bailly N., Kirk P., Nicolson D. (2011). The Catalogue of Life Taxonomic Classification, Edition 2, Part A. In: Species 2000 & ITIS Catalogue of Life: 2011 Annual Checklist (Bisby F.A., Roskov Y.R., Orrell T.M., Nicolson D., Paglinawan L.E., Bailly N., Kirk P.M., Bourgoin T., Baillargeon G., Ouvrard D., eds). DVD; Species 2000: Reading, UK.
Accessed through GBIF Data Portal February 27, 2008:
- GBIF-Spain: Real Jardin Botanico, Madrid: MA-Musci
- Missouri Botanical Garden
- Biodiversity Heritage Library NamebankID: 3337351
- Catalogue of Life Accepted Name Code: MOS-35144695
- Zipcode Zoo Species Identifier: 529442
- Roxanne I. Hastings, Ryszard Ochyra "Grimmiaceae". in Flora of North America Vol. 27 Page 39, 204, 205, 231, 265, 266, 286, 294, 306, 615. Oxford University Press. Online at EFloras.org. [back]
- Ryszard Ochyra, Halina Bednarek-Ochyra "Racomitrium". in Flora of North America Vol. 27 Page 19, 205, 241, 249, 256, 266, 267, 268, 286, 293, 294, 295. Oxford University Press. Online at EFloras.org. [back]