A re-assessment of members of the family Saxifragaceae in the Canadian Arctic Archipelago is presented as a traditional key and annotated checklist that recognizes 17 taxa. The information on which this paper is based is recorded in a developing DELTA database that aims to collect the following data: place of valid publication; synonymy, usually limited to names that have been associated with the Canadian Arctic; common name(s), if applicable; vegetative and floral morphological characters; data on the distribution, including information about the northernmost record of the taxon; habitat preferences of each species; notes on the species as an environmental indicator; indigenous knowledge; and expanded notes conveying additional information. The database also contains maps, illustrations of characters useful for identification, and colour photographs and line drawings of the taxa. Appendices list characters recorded in the database, brief taxonomic notes, and a sample species description. The data are available on the Internet at http://biodiversity.uno.edu/delta/ as natural-language descriptions and as an INTKEY interactive identification and information-retrieval package for Windows.Résumé : Les auteurs présentent une ré-évaluation des membres de la famille des Saxifragaceae de l'archipelle Arctique Canadien, sous forme d'une clé traditionnelle et d'une liste annotée reconnaissant 17 taxons. L'information sur laquelle ce travail est basé est enregistrée dans une banque de données DELTA, en développement, qui vise à réunir les informations suivantes : localisation de publications valides, synonymie habituellement limitée aux noms qui ont été associés avec l'Arctique Canadien, nom(s) commun(s) si approprié, caractères morphologiques végétatifs et floraux, données sur la distribution, incluant de l'information sur la mention la plus nordique pour le taxon, habitats préférés de chaque espèce, notes sur l'espèce comme indicateur environnemental, connaissance par les indigènes, et un ensemble de notes sur des informations additionnelles. La banque de données comporte également des cartes, des illustrations de caractères utiles pour l'identification, des photographies en couleurs ainsi que des dessins de ces taxons. Les appendices présentent les caractères enregistrés dans la banque de données, de courtes notes taxonomiques et un échantillon de description de l'espèce. Les données sont disponibles par Internet à http://biodiversity.uno.edu/delta/ sous forme de descriptions en langage naturel et sous forme d'un fichier transférable INTKEY pour identification interactive et retrait d'informations sur MS-Windows. Mots clés : Arctique, Canada, DELTA, Internet, Saxifragaceae, taxonomie. [Traduit par la Rédaction] Aiken et al. 2036 Porsild (1957Porsild ( , 1964 and incorporated relevant information published since the latter date. The Poaceae was chosen as the first family to be revised, for reasons that were documented. The DELTA format (Description Language for Tax-Can.

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The hypothesized hybrid origin of Pon hnrtzii Gand. (Poaceac) was investigated by analysis of morphological and nlolecular data. This endemic nearctic caespitose grass has been considered to be a hybrid between two of the three sympatric arctic species, Pr~rr glc~~icn M. Vahl, Poll nrcticrr R. Br., and Poa nbbrevintn R. Br. Field obscrvations and morphological studies indicate that Poa hartzii is a n~orphologically distinct apomictic species that reproduces and disperses by seed. Restriction enzyme analysis of polymerase chain reaction amplified chloroplast DNA revealed the presence in Porr hrrrfzii of two very different haplotypes. One haplotype is identical to the dominant type found in Pou g l n~~c n , while the second is identical to the haplotype of Porr sec~rrlrltr J . Presl., located south of the arctic region. These results are consistent with an hypothesis of ancient hybrid origin involving Pon gln~rcrr and Pon sec~rrlclrr, but not Potr arctien nor Poa nbbreviata. They are also consistent with an hypothesis of cytoplasmic transfer via hybridization and introgression from Pon gln~ica to an ancestral Pon hnr~zii in the Pon secrrrzrln con~plex. Direction of transfer is suggested by the widespread occurrence of the Poa .sec~trltlrr haplotype in Poa llartzii and by closer n~orphological similarity with Pntr sec~tr~cln than Potr gln~tcn. The origin of Pon hnrtiii provides an excellent example of reticulate evolution and the importance of hybridization in the speciation of arctic grasses. Resume: Les auteurs ont examine I'origine hybride hypothktique du Poa hrrrtzii Gand. (Poaceae) en analysant des donnees morphologiqucs et moltculaircs. On a souvent considdt-C la graminkc cespiteuses arctique endenlique conlme Ctant un hybride entre deux des trois espiices arctiques sympatriques, Pon glcl~tcrr M. Vahl, Poa arcticel R. Br. et Poc~ nbbreviata R.Br. Les observations aux champs et Ics observations au laboratoire indiquent que le Pon 11urtzii est une espiice n~orphologiquenlent distincte et apomictique, qui se rcproduic et se disperse par graines. L'analysc des patrons dc restriction de I'ADN chloroplastique an1plifi6 par PCR nlontre la prCsencc chez le Poa hnrtzii de deux haplotypes differents. Un haplotype est idcntique au type dominant du Pon gln~rct~, alors quc I'autre est identique 5 I'haplotypc du Pocr sec~rr~rlr, J. Presl. IocalisC au sud de la rkgion arctique. Ces rCsultats sont congruents avec I'hypothksc d'unc originc hybride ancienne impliquant les Poa gla~lcc~ et Poa src~~r~rlcr, nlais non pas les Pon nrctict~ et Pon ~rbbrevit~t~r. II sont Cgalement congruents avec I'hypothksc du transfert cytoplasmiquc par hybridisation et introgression du POLI gln~rcr~ vcrs un Pon hnrtzii ancestral, dans le complexc Pon sec~rrltlrr. La direction du transfert est indiquec par la prCscnce gdncralc de I'haplotype du Poa sec~rrzclc~ chez les Poa hnrtzii et par unc similitude morphologiquc plus etroite avec le Poc~ seatr~clc~ qu'avcc le Pon glrrrrca. L'origine du Pon l~nr/zii constitue en cxcellent exemple d'Cvolution rCt...

A comprehensive re-assessment of grasses in the Canadian Arctic Archipelago is presented as an annotated checklist recognizing 49 taxa. Twenty-five names that have been associated with the flora of the islands are excluded. Information was recorded in a DELTA database. For taxa recognized, the following information is included: common name if applicable, place of valid publication, basionyms, limited synonymy, location of type specimens when known and whether we have seen them, 39 vegetative and 60 floral morphological characters, known chromosome number(s), distribution and habitat data, comments in an annotated checklist, and for many taxa, expanded notes conveying additional information. For 37 of the taxa, their usefulness as environmental indicators is recorded. The above information is also available for some of the excluded taxa; for all of them there are notes explaining why the taxon is excluded. The database is illustrated with 46 maps, 17 line drawings of characters useful for identifications, and photographs of 29 type specimens, 19 herbarium specimens, and 58 photographs of plants in their habitats or close up. The data are available as an INTKEY interactive identification and information-retrieval package for MS-Windows, and as natural-language descriptions in four formats: WWW pages, plain text, PostScript, and HP Laserjet files. Keywords: Poaceae, arctic, taxonomy, WWW, Internet, key.