| BEN |
| BOTANICAL ELECTRONIC NEWS |
|---|
| ISSN 1188-603X |
| No. 341 January 27, 2005 | aceska@victoria.tc.ca | Victoria, B.C. |
|---|
Poa secunda in the broadest sense is distributed over most of western North America with disjunct populations in the Gaspe Peninsula, Quebec and another in Chile. It is a complex of apomictic forms and as many as 45 "species" have been described in this complex (Kellogg 1990). On the other hand, more conservative botanists would treat all the forms as a single species (Marsh 1952), or only two species (Kellogg 1985, Kartesz 1994).
A.S Hitchcock (1950) treats this complex as two separate sections of the genus Poa (i.e., sect. Scabrellae and sect. Nevadenses) with four species in each section for the total of eight species. Kellogg (1985b) pointed out that it is difficult to identify those species: "either the keys need improvement or the 'species' are not really distinct."
Kellogg herself recognized that there was more variation within this group than could be encompassed by one or two single species: "It may still be useful for range managers to have a name for some of the groups formerly called species. For instance, the large plants with long glaucous leaves, short ligules and sparse pubescence on the lemmas are distinctive in their extreme form even though all characters integrade fully with the rest of Poa secunda" (Kellogg 1985, p. 521).
Larson et. al. (2001) performed the DNA analysis of several samples from the Poa secunda complex and found only "little divergence between two "Sandberg bluegrass" populations [i.e., Poa sandbergii (Reichart) A.S. Hitch. = Poa secunda J. Presl], collected from sites nearly 600 km apart." On the other hand, Canbar cultivar of "Poa canbyi" (2n = 63) and Shearman cultivar of "Poa ampla" (2n = 84) were quite different from the natural "Sandberg bluegrass" populations. However, we can expect such clear cut differences, if we deal with cultivars (as Larson et al. did) instead of plants from natural populations.
About eight "species" has been recognized within this complex. These eight "species" that have been consistently mentioned in the "Poa secunda" treatment by A.C. Hitchcock & Chase (1950), Hitchcock et al. (1969), Cronquist et al., and even by Kellogg (1985). The key for their identification adapted from Cronquist et al. (1977) is given below.
Poa incurva Scribn. & Williams, not included in this key, is a higher elevation "species" (described from the Olympic Mtns.) that is viewed by some as "Poa secunda of higher elevations", or as a "higher elevation form of Poa canbyi".
Apomictic complexes pose a problem to classification. In the case of the Poa secunda aggregate, to recognize 45 "small species" is unrealistic. At the same time, I think it is equally incorrect to ignore sets of morphological or distributional information and treat the whole complex as only one or two species.
Wisskirchen & Hauepler (1998) give an interesting precedent on how to deal with this problem. In their list of Vascular Plants of Germany, they present two versions of the Oenothera classification. One, presented by a "lumper" recognized 7 species (including two nothospecies) in this genus in Germany, the other, a "splitter" that recognized 46 species (including 7 nothospecies) in the same complex.
I do not want to pretend that I understand the Poa secunda aggregate, but I am quite happy to call our lowland plants on Vancouver Island Poa canbyi and those from the higher elevations Poa gracillima, instead of calling them all "Poa secunda". If we ignore those "small species" and the differences between them, every second Poa collected in the Pacific Northwest will turn out to be Poa secunda.
Characteristics of the "Poa secunda" s.lato
Spikelets little compressed, narrow, much longer than wide; the lemmas convex on the back; the keels obscure and intermediate nerves usually faint. All bunchgrasses.
1. Lemmas crisp-puberulent on the back toward the base (the
pubescence sometimes obscure or only at the very base)
........................................... Sect. Scabrellae
2. Sheaths somewhat scabrous ............... Poa scabrella
2. Sheaths glabrous
3. Panicle rather open, the lower branches naked at the
base, ascending or somewhat spreading; culms usually
decumbent at base .................... Poa gracillima
3. Panicle contracted, the branches appressed or at
anthesis somewhat spreading.
4. Culms slender, on the average less than 30 cm tall;
numerous short innovations at base; blades usually
folded .............................. Poa secunda
4. Culms stouter, on the average more than 50 cm tall;
innovations not numerous ............. Poa canbyi
1. Lemmas glabrous or minutely scabrous, but not crisp-
puberulent ................................ Sect. Nevadenses
5. Sheaths scaberulous; ligules long; decurrent
......................................... Poa nevadensis
5. Sheaths glabrous.
6. Ligules prominent; blades broad and short
..................................... Poa curtifolia
6. Ligules short; blades elongate.
7. Blades involute .................. Poa juncifolia
7. Blades flat ........................... Poa ampla
Pleurocarpous mosses, characterized by lateral female gametangia and highly branched, interwoven stems, comprise three orders and some 5000 species, or almost half of all moss diversity. Recent phylogenetic analyses resolve the Ptychomniales as sister to the Hypnales plus Hookeriales. Species richness is highly asymmetric with approximately 100 Ptychomniales, 750 Hookeriales, and 4400 Hypnales. Chloroplast DNA (cpDNA) sequences were obtained to compare partitioning of molecular diversity among the orders with estimates of species richness, and to test the hypothesis that either the Hookeriales or Hypnales underwent a period (or periods) of exceptionally rapid diversification. Levels of biodiversity were quantified using explicitly historical "phylogenetic diversity" and non-historical estimates of standing sequence diversity. Diversification rates were visualized using lineagethrough-time (LTT) plots, and statistical tests of alternative diversification models were performed using the methods of Paradis (1997). The effects of incomplete sampling on the shape of LTT plots and performance of statistical tests were investigated using simulated phylogenies with incomplete sampling. Despite a much larger number of accepted species, the Hypnales contain lower levels of (cpDNA) biodiversity than their sister group, the Hookeriales, based on all molecular measures. Simulations confirm previous results that incomplete sampling yields diversification patterns that appear to reflect a decreasing rate through time, even when the true phylogenies were simulated with constant rates. Comparisons between simulated results and empirical data indicate that a constant rate of diversification cannot be rejected for the Hookeriales. The Hypnales, however, appear to have undergone a period of exceptionally rapid diversification for the earliest 20% of their history.
This is a magnificent collection of essays that covers the yes! - natural history of ferns. Some of the essays were originally published in the Fiddlehead Forum (a newsletter of the American Fern Society) and one in its British equivalent, Pteridologist. Two of them (In search of the fern seeds and Nardoo) were also posted in BEN.
Robbin Moran's captivating style made this collection an excellent read and an easy introduction to various aspects of pteridophytes. However, it is also a scholarly work, and is an excellent source of information on ferns and their natural history.
Thirty three essays cover all aspects of ferns and the so-called fern allies. The book is richly illustrated with 145 figures and 25 colour plates, and the illustrations are an integral part of the book. There are not too many nor too few, just right for the treated topics. As a matter of fact, when I posted two of Robbin Moran's essays in BEN, I had a hard time finding some that could stand on their own without their accompanying illustrations. "This book relies heavily on illustrations," writes Robbin Moran in the Acknowledgements and he thanks Haroto M. Fukuda for preparing many of the drawings. With quite a few drawings taken from the published literature, the author (and I assume Haroto M. Fikuda as well) managed to combine different styles very well. The result is a uniform visual feast, not a hodgepodge of pictures randomly thrown together.
This is a beautiful book. Get it, read it, and become a pteridophyte addict. I warn you, this is a dangerous obsession. Pteridophytes are like cats: you have to like them, you are always amazed by them, but you will never understand them. Good luck!
This database contains biological and ecological characteristics of the vascular plants of Germany. It gives detailed information on 3659 species of vascular plants. For each species the information contains data on over 60 characteristics, such as the status in the German flora (native, introduced, or just frequent ephemeral escapes from cultivation), chromosome numbers, morphology, flower biology, fruit and seed characteristics, distributional characteristics and ecological and phytosociological characteristics. In addition, the database is loaded with pertinent literature citations that direct you to further reading or further details (over 1800 sources).
All the characteristics listed and classified in the database are covered in the book (334 pages) that treat every listed characteristic in detail. This book itself gives you a good idea about what you can "see" when you look at any vascular plant. It will show you what characteristics you can or should look at when you deal with a particular species. Even without a database, this cover volume is a good introduction to all aspects of plant biology, be it phytogeography, chromosome numbers, morphology, phenology, ecology or phytosociology. The references listed in this accompanying volume give you all the essential literature important in the descriptive botany.
I received a complimentary copy of this book and CD from one of the authors, who is a long-time BEN subscriber and who also contributed to BEN in the past. If you get the book, or if you buy it, the CD that you get with the book has your registration number and you can access the main database at http://www.ufz.de/biolflor/ . I have to confess that I lost my CD somewhere in the basement (I call my basement "Schwarzes Loch" and it has all the astrophysical properties of a black hole), but I had managed to register before I lost sight of my registration number. I access the BiolFlor database online quite frequently and I always find the information I am looking for. However, given my ecological bias, I would like to have seen the Ellenberg indicator values listed in the database.
The database, when you access it, is bilingual and you can import the species data into either German or English frames. My English legend is slipping off and is being replaced with the German one, but that's not a great inconvenience. When something like that happens, I always blame Bill Gates for it.
I hope that this database will remain dynamic. That means that the new data, new references, and - if necessary - new taxa will be added, and all the nomenclatural changes of names will be tracked. This keeping the database up to date is a tremendous job on its own, but it is worthwhile to keep all the information in the database fresh and current. I hope that the database owners (Bundesamt f. Naturschutz) have put aside some funds for database maintenance.
It had to be a tremendous job to put all this information together and both the authors, all the contributors, as well as the Bundesamt fuer Natrurschutz, should be congratulated to the work well done.
This site provides access to the Missouri Botanical Garden's VAST (VAScular Tropicos) nomenclatural database and associated authority files.
It contains current information on the name, its place of publication, type, and other information about the majority of North American vascular plants.
W3TROPICOS provides new and improved access to the Missouri Botanical Garden's VAST nomenclatural database and associated authority files. In this release (rev. 1.5), the following information is provided when present (* indicates a hypertext link to additional information about a name or reference):
Names data
Plant name and authors
Group and family
placement
Place and date of
publication Type
information
*Basionym, with place and date of publication
*Next Higher Taxon, with place and date of publication
*Other uses of this name
*Synonyms of this name, and *References for the
alternate usage *Homonyms and *Infraspecific names
for species
Reference
Author(s) of the publication
Date of
publication
Title of
the article
Journal or
book title
Volume and
page
numbers
Keywords
Example:
You can trace up the "nomenclatural history" of any North American plant.
Are you interested in the Cordilleran populations of Douglas- fir?
It was originally described as a variety:
Pseudotsuga menziesii var. glauca (Mayr) Franco Group -
Gymnosperm - Family - PINACEAE - Pine Family Published in:
Boletim da Sociedade Broteriana II 24: 77. 1950.
{Bol. Soc. Brot. ; BPH 211.01}
Basionym:
Pseudotsuga douglasii var. glauca (Beissn., in Jager & Beissn.) Mayr
Wald. Nordamer. 307, t. 6. 1890.
Next Higher Taxon:
Pseudotsuga menziesii (Mirb.) Franco
Boletim da Sociedade Broteriana, ser. 2 24: 74. 1950.
Later it was elevated into the subspecies:
Pseudotsuga menziesii subsp. glauca (Beissn., in Jager &
Beissn.) E. Murray
Group - Gymnosperm - Family - PINACEAE - Pine Family
Published in:
Kalmia 12: 24. 1982.
{Kalmia }
Basionym:
Tsuga douglasii var. glauca Beissn., in Jager & Beissn.
Ziergeh. Gart. Park ed. 2 446. 1884.
Next Higher Taxon:
Pseudotsuga menziesii (Mirb.) Franco
Boletim da Sociedade Broteriana, ser. 2 24: 74. 1950.
Finally, it was recognized as a species different from the
coastal Pseudotsuga menziesii s.str.:
Pseudotsuga glauca (Beissn., in Jager & Beissn.) Mayr.
Group - Gymnosperm - Family - PINACEAE - Pine Family
Published in:
Mitteilungen der Deutschen Dendrologischen Gesellschaft
1901: 57. 1901.
{Mitt. Deutsch. Dendrol. Ges. ; BPH 603.04}
Basionym:
Tsuga douglasii var. glauca Beissn., in Jager & Beissn.
Ziergeh. Gart. Park ed. 2 446. 1884.
Next Higher Taxon:
Pseudotsuga Carrière
Traité général des conifères 1: 256. 1867.
A course on Multivariate analysis of ecological data will be held in Ceske Budejovice, Czech Republic 19 - 30 July 2005. Lecturers, Jan Leps and Petr Smilauer, are authors of the book Multivariate analysis of ecological data using CANOCO, published by Cambridge University Press - see: http://www.cplpress.com/contents/C1172.htm
For more information on the course see http://regent.bf.jcu.cz/
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