Guide to Species of Racomitrium in Oregon


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INTRODUCTION--- HOW TO USE THE KEYS--- BREADCRUMBS--- THUMBNAILS--- INDEX TO SPECIES--- REGARDING PAPILLAE--- REGARDING TWIST--- BACKGROUND--- COMMENTS--- ACKNOWLEDGEMENTS

INTRODUCTION

This key is a regional summary and reworking of the treatment of Racomitrioideae in the Flora of North America (FNA), v. 27 (Ochyra and Bednarek-Ochyra 2007). These authors divided the traditional genus Racomitrium into four genera that reflect reasonably natural groupings. Whether these narrowly defined genera represent monophyletic clades was never clear to me and I wondered if they would gain acceptance at generic rank when phylogenetic data from cladistic and/or molecular analyses became available. A recent paper indicates that the genera are not supported by a phylogenetic interpretation that included both morphological and molecular analysis(Larraín et al., 2013). For the field botanist, for whom the primary issue is confident identification of species, it remains convenient to consider them together as the traditionally circumscribed genus. This is particularly true when dealing with identification based mainly on vegetative characters. The field botanist often does not have reproductive structures available and vegetative characters overlap among the segregate genera. The key that forms the core of this guide relies almost entirely on leaf characters as primary discriminators. To avoid confusion between Racomitrium in the traditional, broad sense and Racomitrium in the narrow sense (with only one species) I treat all of them in this document as Racomitrium in the broad sense. These mosses do not have common names, so I use "racomitrium" and "racomitriums" in decapitalized, non-italicized format as common names for the genus in its broad sense.

For those who pefer the segregate genera used by Bednarek-Ochyra and Ochyra in the FNA, synonyms are given on each species page; authorities are also quickly found on the "Index to Species" page. There are also synonyms for the segregate genera at the subgenus rank which may be used if one wishes to recognize the segregates without having to use the rank of genus. Following are the equivalents:
Niphotrichum = Racomitrium subgenus Niphotrichum Bednarek-Ochyra
Codriophorus = Racomitrium subgenus Cataractae Bednarek-Ochyra
Bucklandiella = Racomitrium subgenus Ellipticodryptodon Villella.

This key should work well in California but some species known to occur in Washington are not included. Based on the catalog of California mosses by Norris and Shevock (2004a), the distributions given in the Flora of North America, and personal experience, I have selected 20 species to include in this guide. The list includes several species which have not yet been found in Oregon but whose occurrence in adjacent states indicates they are likely to grow here. There is much exploration to be done.

INTRODUCTION--- HOW TO USE THE KEYS--- BREADCRUMBS--- THUMBNAILS--- INDEX TO SPECIES--- REGARDING PAPILLAE--- REGARDING TWIST--- BACKGROUND--- COMMENTS--- ACKNOWLEDGEMENTS

HOW TO USE THE KEYS

From the home page go to the main key. Each page in this key is a couplet with two contrasting leads. Decide which lead best fits the specimen being studied. Click on the primary character in a lead to go to the next couplet or to a species page. Every page has a link to the home page at the top and bottom.

BREADCRUMBS

At the top of every key page there is a line of breadcrumbs. This is a series of links to the leads in each couplet taken to arrive at this page. It is a shorthand record of choices made. You can go back to any step in the keying process by clicking on the appropriate phrase in the breadcrumb trail. Clicking on the first breadcrumb will take you back to the start of the key.

INTRODUCTION--- HOW TO USE THE KEYS--- BREADCRUMBS--- THUMBNAILS--- INDEX TO SPECIES--- REGARDING PAPILLAE--- REGARDING TWIST--- BACKGROUND--- COMMENTS--- ACKNOWLEDGEMENTS

THUMBNAILS

All images on the key pages and the species pages are thumbnails. Click on a thumbnail to see a large image. These high resolution images may be be larger than your screen depending on your browser settings. They have been saved at 1000 pixels high to retain reasonably good resolution for printing. Use your back arrow, "Show the previous page," to return to the page on which the thumbnail was located.

HOW TO USE THE KEYS--- BREADCRUMBS--- THUMBNAILS--- INDEX TO SPECIES--- REGARDING PAPILLAE--- REGARDING TWIST--- BACKGROUND--- COMMENTS--- ACKNOWLEDGEMENTS

INDEX TO SPECIES

From home page go to Index of Species to find a list of all names with authorities. All names are linked to a species page, with all the species pages listed under Racomitrium with the genera as found in FNA listed as synonyms. I like to bookmark this index because at any point I may want to go directly to a species page to check if a specimen in hand fits the species descriptions and to see additional pictures for comparison.

All images used in the key are repeated on the appropriate species page. Most species pages have additional photomicrographs. Thanks to permission from Bednarek-Ochyra, if a plate made by Halina Bednarek-Ochyra has been published for the species, it will be accessed by clicking on the thumbnails following the photomicrographs. These thumbnails are the figure legends for each plate. As with the photomicrographs, the full size plates are large files, saved at original size so when printed out they will come close to having original clarity.

INTRODUCTION--- HOW TO USE THE KEYS--- BREADCRUMBS--- THUMBNAILS--- INDEX TO SPECIES--- REGARDING PAPILLAE--- REGARDING TWIST--- BACKGROUND--- COMMENTS--- ACKNOWLEDGEMENTS

REGARDING PAPILLAE

One of the incentives for creating a key with photomicrographs is to illustrate the variation in leaf surface ornamentation found in these plants. When present, the type of papillae is an important character widely used in distinguishing species of mosses. The papillae of racomitriums come in forms that are not common elsewhere among the mosses.

Elva Lawton (1971) writes, "There are a number of different kinds of papillae in Rhacomitrium as well as in other genera, and a thorough study, with clear definitions and perhaps names for different forms, is desirable. Sinuose cell walls complicate the problem because in some species the cells may appear papillose in surface view when no papillae are evident in section. Cross walls may be strongly thickened, bulging dorsally and ventrally, and in section may resemble papillae. In the keys, cells with bulging walls are not considered papillose." It is these thickenings of the longitudinal cross walls on each surface of the leaf that gives rise to the sinuose-nodose appearance when the leaf is examined in surface view.

In his monograph, Frisvoll (1988) called these bulging ends of cross walls, "pseudopapillae." Ochyra and Beddarek-Ochyra also refer to these bulging cross walls as "pseudopapillae." On the other hand, they place great emphasis on recognizing the true papillae that characterize the genus Codriophorus. In her monograph, Bednarek-Ochyra (2006) writes, "The cells in the majority of Codriophorus species are distinctly papillose in a peculiar manner with large, flat papillae distributed on both the dorsal and ventral surfaces of the leaf over the longititudinal walls and major part of the lamina, leaving only a narrow split in the middle." I do not understand why these are called "true" papillae. They are formed by bulging cross walls which spread out over the lumens of the cells instead of bulging outwards. I have to consider them all pseudopapillae. This kind of papilla was noted by Lawton only in R. fasciculare while the other species of subgenus Cataractae (Codriophorus) she described in various ways, e.g., "with several small papillae per cell" in R. aciculare. Bednarek-Ochyra (2007) observes that this species actually has the large flat papillae characteristic of the subgenus Cataractae but in addition has small papillulae on top of the papillae! A similar situation has been observed in Racomitrium varium.

The photomicrographs presented here should help illuminate what is described in the literature. There are, indeed, species specific characteristics of leaf ornamentation but they elude precise verbal definitions. Among the racomitriums, the only papillae that everybody recognizes readily are those on the hairpoints of Racomitrium lanuginosum and leaf cells of subgenus Niphotrichum.


INTRODUCTION--- HOW TO USE THE KEYS--- BREADCRUMBS--- THUMBNAILS--- INDEX TO SPECIES--- REGARDING PAPILLAE--- REGARDING TWIST--- BACKGROUND--- COMMENTS--- ACKNOWLEDGEMENTS

REGARDING TWIST

Although this key depends mainly on vegetative characters, the direction a seta twists is a very useful character in placing species in the correct genus. This is something that can be determined in the field with a 10X handlens. It is not easy at first but with a bit of practice the twist direction can be observed with 100% accuracy.

In contemporary scientific terminology a right handed twist (best example: DNA) is defined as a helix inscribed by a point spiraling away from the viewer in a clockwise motion, such as a point on the lid of a jar as it is being tightened while you are looking down on it. A left handed twist is a helix inscribed by a point spiraling away in a counterclockwise motion. In more practical terms, based on looking at a vertically oriented seta from the side, right handed twists go up to the right and left handed twists go up to the left.

Racomitrium lanuginosum and all species in the subgenus Niphotrichum have a right handed twist to their setae. Noting this will help confirm genus identification in the field as a supplementary character to the greyish white, hoary appearance of these plants.

All of the other species of Racomitrium have a left handed twist to the dry seta except Racomitrium lawtoniae. This will help distinguishing in the field whether a species similar to Racomitrium heterostichum is at hand or a look alike in the genus Grimmia. It is not unusual for the less common species of Racomitrium to hide among extensive patches of Grimmia, such as G. trichophylla or G. leibergii. All the species which mimic Racomitrium have a right handed twist to their setae and a ribbed capsule with undivided peristome teeth which differentiates them from left twisted seta and cylindrical capsules with forked peristome teeth found in Racomitrium.


Racomitrium heterostichum. Note left handed twist of seta! Memaloose Park, Wasco Co., Oregon. DHW m0817i.



Grimmia leibergii. Note right handed twist of seta. North Cascades National Park, Whatcom County, Washington. Hutten 7780.(Herbarium of North Cascades National Park)



Note that some botanists, including Bednarek-Ochyra (1995) and Ochyra and Bednarek-Ochyra (2007), use a traditional but now deprecated terminology which is the opposite of contemporary scientific usage, e.g., using "sinistrorse" for a right handed twist and "dextrorse" for a left handed twist. Clear pictures demonstrating the correct usage of these terms can be found in the excellent illustrated glossary by Bill and Nancy Malcolm (2006, p. 110.).

Far more confusing is the use of clockwise and counterclockwise, without any qualifier, to describe the direction of twist. These terms describe a two dimensional trait while twist is a three dimensional character. A reference point plus direction of movement on a third axis must be specified in addition to clockwise/counterclockwise to define a twist.

When Lawton (1971) uses clockwise, she is referring to a left handed twist and with counterclockwise she refers to a right handed twist. In only one place do Ochyra and Bednarek-Ochyra (2007) use clockwise: in describing the seta twist of Racomitrium (Bucklandiella) lawtoniae. This is the only species of subgenus Ellipticodryptodon with a right handed twist to the dry seta. Ironically, it is the only species in the subgenus Ellipticodryptodon where the seta twist is mentioned in the species descriptions in the FNA. Because clockwise is used without qualifiers, it is not clear that these authors have noticed the distinctiveness of the seta twist in Racomitrium lawtoniae, thus using the term in a manner opposite to Lawton's, or if they have simply overlooked it and equated clockwise with dextrorse (the term they use for left handed twist).

INTRODUCTION--- HOW TO USE THE KEYS--- BREADCRUMBS--- THUMBNAILS--- INDEX TO SPECIES--- REGARDING PAPILLAE--- REGARDING TWIST--- BACKGROUND--- COMMENTS--- ACKNOWLEDGEMENTS

BACKGROUND

A current understanding of the racomitriums of Oregon could begin with Elva Lawton, who studied the genus thoroughly in preparation for her manual on mosses of the Pacific Northwest (Lawton 1971). Her work continues to be very useful and fortunately remains in print. (Note: she spelled the genus Rhacomitrium, a common, older, but now rejected variant spelling of the genus name.) She wrote quite usable keys which, however, lumped together a number of forms now recognized as species. People trained on Lawton's keys should be aware that there are now several species recognized for each of three species: Racomitrium canescens, R. heterostichum, and R. sudeticum. The person most responsible for clarifying species distinctions in these groups is Arne Frisvoll, whose work stands today as benchmark of careful work (Frisvoll 1983, 1988). Building on this standard of critical study, Halina Bednarek-Ochyra and her husband, Ryszard Ochyra, have described two new species from our flora and, in providing a treatment for the Flora of North America, have established the most recent assessment of the racomitriums (Ochyra and Bednarek-Ochyra 2007). This guide has been created with the bryologically tuned field botanists of the Pacific Northwest in mind. I hope that it will encourage them to continue expanding our collective knowledge of the bryophytes of our region.

My own interest in the genus has been fairly continuous over the past thirty years, slow at first and with a burst of interest in the 1990's when I began extensive inventory work in SW Oregon. Racomitrium in the broad sense is a key component of most exposed rock habitats, from streamside canyons to alpine ridges. It is not unusual to find several species growing on one rock. Some are common, some are rare. Learning to sort them out has been an engaging challenge. I have made two efforts to share what I have learned. The first was a booklet of illustrations of racomitriums (Wagner 1998) which summarized my understanding of the plants up to that time. (Note: what was labeled R. sudeticum in that booklet is actually R. occidentale.) In 2001 I began a digitized pictorial survey of Racomitrium s.l. which was never published. I have given electronic copies to participants in my bryophyte workshops. This guide is the next step in this effort. The goal has been to provide a guide that is both useful and takes advantage of digital formats.

INTRODUCTION--- HOW TO USE THE KEYS--- BREADCRUMBS--- THUMBNAILS--- INDEX TO SPECIES--- REGARDING PAPILLAE--- REGARDING TWIST--- BACKGROUND--- COMMENTS--- ACKNOWLEDGEMENTS

COMMENTS:

Please send any questions or suggestions to:

davidwagner@mac.com

The photomicrographs in this document are available for general use. Please credit properly when used in other venues. Higher resolution versions are archived and available upon request. All the photographed specimens are provided with specimen data and, if not specifically ascribed, all are in my personal herbarium.

INTRODUCTION--- HOW TO USE THE KEYS--- BREADCRUMBS--- THUMBNAILS--- INDEX TO SPECIES--- REGARDING PAPILLAE--- REGARDING TWIST--- BACKGROUND--- COMMENTS--- ACKNOWLEDGEMENTS

ACKNOWLEDGEMENTS:

I am indebted to several Bureau of Land Management botanists who have provided opportunities to explore and study the mosses of their districts. These include Nancy Wogen, Russ Holmes, Joan Seevers, Bruce Rittenhouse, Mark Mousseaux, and Ron Exeter. Also pertinent to this effort is the support of the U.S. Forest Service, in particular on the Winema Forest as coordinated by Sarah Malaby. Their encouragement to do field work and pass on what I have learned has been of inestimable value to me. I have received critical specimens to study from Ed Berg of the Kenai National Wildlife Refuge, Ron Exeter of Salem BLM, and Robin Lesher of the Mt. Baker-Snoqualmie National Forest. Dave Kofranek of Eugene has discovered and forwarded many interesting collections. Wilf Schofield and Judy Harpel assisted with reviews of identifications early in my work. For continuing advice and encouragement I am grateful to the gracious and generous communication from Ryszard Ochyra and Halina Bednarek-Ochyra; likewise Dan Norris and Jim Shevock have been very helpful in the field, lab, and in letters. I have been given space to work in the herbaria of Oregon State University, University of California at Berkeley, California Academy of Sciences, and University of Washington; the latter has loaned me specimens. I am grateful to the curators of these institutions for these courtesies.


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Guide to Racomitrium of Oregon.
Created 2007 Northwest Botanical Institute.