The genus Atriplex (Chenopodiaceae) in Canada. II. Four native western annuals: A. argentea, A. truncata, A. powellii, and A. dioica

1970 ◽  
Vol 48 (5) ◽  
pp. 981-989 ◽  
Author(s):  
C. Frankton ◽  
I. J. Bassett
Keyword(s):  
North America ◽  
Chromosome Number ◽  
Pollen Grains ◽  
Distribution Data ◽  
Western North America ◽  
Annual Species ◽  
Scanning Electron

Descriptions, illustrations, and distribution data are given for four annual species of Chenopodiaceae native to western North America: Atriplex argentea Nutt., A. truncata (Torrey) Gray, A. powellii Watson, and A. dioica (Nutt.) Macbr. All four species have the same chromosome number, 2n = 18. Scanning electron photomicrographs of the pollen grains are included.

Palynological analysis of five selected Onosma taxa

Biologia ◽  
2008 ◽  
Vol 63 (2) ◽  
Author(s):  
Filippo Maggi ◽  
Vladislav Kolarčik ◽  
Pavol Mártonfi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Chromosome Number ◽  
Pollen Grains ◽  
Pollen Size ◽  
Palynological Analysis ◽  
Positive Correlation ◽  
Pollen Characters ◽  
Scanning Electron

AbstractPollen size and exine structure of the following five Onosma L. species from Slovakia and Italy were studied by light and scanning electron microscopy: Onosma echioides, O. tornensis, O. visianii, O. arenaria, and O. pseudoarenaria. Among the taxa studied, O. echioides has the smallest pollen grains in average (10.5–17.5 × 8.0–14.5 µm), and O. pseudoarenaria the largest grains in average (15.3–20.5 × 12.3–16.3 µm). Pollen grains of all 5 species are small sized, 3-syncolporate, subprolate, heteropolar, with ovate equatorial outlines and circular to rounded triangular polar outlines; the tectum is microechinate. A positive correlation is found between pollen size and chromosome number. The value of pollen characters for taxonomic purposes and the position of the taxa studied within the genus Onosma are discussed.

Impact of Alien Plants on Grant Basin Rangelands

1996 ◽  
Vol 10 (2) ◽  
pp. 384-391 ◽  
Author(s):  
James A. Young ◽  
William S. Longland
Keyword(s):  
North America ◽  
Great Basin ◽  
Alien Plants ◽  
Western North America ◽  
Biological Functions ◽  
Annual Species ◽  
Weed Species ◽  
Model Ecosystem ◽  
Alien Weed ◽  
The Impact

Our purpose is to discuss the impact of alien plants on rangeland ecosystems of the Great Basin in terms of their effects on biological functions. The sagebrush/bunchgrass ranges of western North America are used as a model ecosystem for the impact of alien plants. Alien weed species have been introduced in successive waves, with the success of each new introduction dependent on how well adapted to the environment and how competitive the new weed is with those previously introduced. Annual species have been successful across extensive areas of Great Basin rangelands. Biennial and short- and long-lived perennial introductions have been restricted to much more specific habitats. Alien plants impact rangelands through stand renewal and successional processes. Alien weeds can cause such processes to be accelerated and/or truncated depending on the species and range site.

STUDIES ON SOLIDAGO L.: IV. THE CHROMOSOME NUMBERS OF CERTAIN TAXA OF THE GENUS SOLIDAGO

1959 ◽  
Vol 37 (2) ◽  
pp. 209-228 ◽  
Author(s):  
Jean R. Beaudry ◽  
Denise L. Chabot
Keyword(s):  
North America ◽  
Chromosome Number ◽  
Geographical Distribution ◽  
Chromosome Numbers ◽  
Morphological Characters ◽  
Basic Number ◽  
Western North America

The authors report the chromosome numbers of 25 taxa of the genus Solidago which had not yet been studied from this standpoint, and review the literature. The chromosome numbers of 42 taxa have now been published. The basic number of the genus is nine. Thirty-three taxa are diploid (2n = 18), five are tetraploid (2n = 36), three are aggregate taxa containing both diploid and tetraploid cytodemes, and one is hexaploid (2n = 54). Polyploidy has thus contributed to the evolution of the genus Solidago but it seems that most of the species have differentiated gradually. S. decemflora DC. of western North America differs from S. nemoralis Ait. of the same continent by morphological characters, its geographical distribution, and its chromosome number, the first taxon being tetraploid and the second diploid; the two are thus good species and not only varieties of the same species. The S. rigida of authors is an aggregate made up of two entities which are distinguished not only by their morphology and geographical distribution but also by their chromosome numbers; the eastern one (S. rigida L.) is tetraploid, whereas the western one (S. parvirigida Beaudry) is diploid. The bog and marsh goldenrods, S. Purshii and S. uliginosa, also possess different chromosome numbers, the first being diploid and the second tetraploid.

Cytotaxonomic studies of Draba species of Canada and Alaska: D. ventosa, D. ruaxes, and D. paysonii

1971 ◽  
Vol 49 (8) ◽  
pp. 1455-1460 ◽  
Author(s):  
Gerald A. Mulligan
Keyword(s):  
North America ◽  
Chromosome Number ◽  
Related Species ◽  
Basic Chromosome Number ◽  
Base Number ◽  
Western North America ◽  
Closely Related Species ◽  
Basic Chromosome ◽  
Hexaploid Species

The cytotaxonomy of three closely related species of Draba, of the mountains of western North America, is discussed and a key is given: D. ventosa A. Gray (2n = 36), D. ruaxes Payson & St. John (2n = ca. 72), and D. paysonii Macbride (2n = 42). Evidence is presented demonstrating that D. ventosa and D. paysonii are triploids reproducing by agamospermy whereas the hexaploid species D. ruaxes is a sexual outcrosser. The former two species produce seed apomictically without any pollen stimulation. Draba ventosa and D. ruaxes have the basic chromosome number x = 12 and D. paysonii has the base number x = 14.

scholarly journals The species of Mentzelia (Loasaceae) in Mexico, part 2: Mentzelia section Bartonia

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
John Schenk ◽  
Carolina Granados Mendoza ◽  
Andres Eduardo Estrada-Castillón
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Species Diversity ◽  
North America ◽  
Species Identification ◽  
Seed Coat ◽  
Western North America ◽  
Distribution Ranges ◽  
Scanning Electron ◽  
Study Species

Background: Mentzelia (Loasaceae) is primarily distributed in western North America. The genus is classified into six monophyletic sections, among which species of section Bartonia are particularly poorly understood. Questions: What species of Mentzelia section Bartonia occur in Mexico? What are the species distribution ranges and what are their defining attributes? Study species: Mentzelia section Bartonia. Methods: Field, herbarium, distribution, and scanning electron microscopy studies were conducted to assess species diversity. Seed coat microsculpture patterns were evaluated to confirm species identities and understand their distributions throughout Mexico. Results: Six species from section Bartonia were recognized, with taxa distributed into either the Chihuahuan or Sonoran deserts. Mentzelia longiloba var. pinacatensis is the only Mexican endemic. Conclusions: Although this work comprehensively addressed the species of section Bartonia in Mexico, two groups will continue to present identification challenges: the M. longiloba and M. mexicana-M. saxicola complexes. Overlapping and variable characters will continue to complicate species identification in the M. longiloba complex, while the late-season loss of primary leaves will obscure species identification between M. mexicana and M. saxicola.

A clarification of the chromosome number situation in Sanguisorba canadensis

1973 ◽  
Vol 51 (11) ◽  
pp. 2075-2077
Author(s):  
Gerald A. Mulligan ◽  
William J. Cody
Keyword(s):  
North America ◽  
Chromosome Number ◽  
North American ◽  
Western North America

Although eastern North American populations of Sanguisorba canadensis L. are reported to be octoploid and plants of western North America reported to be tetraploid, it was found that this species is usually tetraploid, 2n = 28, throughout its range. No octoploids were found among the plants studied, even in material from the locations where octoploids have been reported to occur.

Palynological analysis and taxonomic position of the genus Mertensia (Boraginaceae)

Botany ◽  
2012 ◽  
Vol 90 (8) ◽  
pp. 722-730 ◽  
Author(s):  
Tomoko Fukuda ◽  
Hiroshi Ikeda
Keyword(s):  
North America ◽  
Pollen Grains ◽  
The Other ◽  
Taxonomic Position ◽  
Western North America ◽  
Pollen Type ◽  
Palynological Analysis ◽  
Distinct Genus ◽  
Morphological Differences ◽  
Himalayan Species

Palynological analysis of the genus Mertensia Roth, s. lat. (Boraginaceae) was performed. All pollen grains studied were mostly dumbbell shaped and had 6-heteroaperturate pollen type without exception. The type of pollen of Mertensia does not contradict recent classifications that assign Mertensia to Cynoglosseae. Among six sections of Mertensia, pollen grains of section Oreocharis (the Himalayan Mertensia) were different from those of other sections in having granulate sculpturing on the colpus and pseudocolpus membranes. The results, along with other morphological differences, may support Riedl’s treatment of the Himalayan species of Mertensia in the distinct genus Pseudomertensia Riedl. Of the other sections, four monotypic sections (sections Steenhanmera, Neuranthia, Typomertensia, and Mertensianthe) showed pollen structures similar to each other. Pollen grains in section Eumertensia had some variations in size and ornamentation, especially in the species distributed in western North America.

The annual species of stinging nettle (Hesperocnide and Urtica) in North America

1976 ◽  
Vol 54 (3-4) ◽  
pp. 374-383 ◽  
Author(s):  
D. W. Woodland ◽  
I.J. Bassett ◽  
C. W. Crompton
Keyword(s):  
North America ◽  
Chromosome Number ◽  
Chromosome Numbers ◽  
Annual Species ◽  
Chromosome Counts ◽  
Stinging Nettle ◽  
The One ◽  
North America North

Descriptions (including those of pollen), distributional data, and chromosome counts are given for one species of Hesperocnide and three annual species of Urtica (stinging nettles) in North America north of Mexico: Hesperocnide tenella, Urtica chamaedryoides, U. gracilenta, and U. urens. Hesperocnide tenella has a chromosome number of 2n = 24 while all three Urtica spp. have the same chromosome number of 2n = 26. All reported chromosome numbers are new except the one for U. urens. A key which separates the taxa that are studied is provided and synonyms that are applied to the species are discussed.

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