Atriplex argentea

Abstract: Photosynthetic pathways (e.g. C3, C4) and morphological functional types (e.g. trees, shrubs, high perennial grasses, perennial forbs) were identified for the native species from the Saskatchewan mixed prairie, using the data from references published between 1950 and 2003. Of the total 219 identified species in 145 genera and 45 families, 208 species in 137 genera and 44 families were found with C3 photosynthesis, and most of these species are dominants (e.g. Agropyron dasystachyum Hook. and Stipa spartea var. curtiseta Hitchc.). 11 species in 10 genera and 3 families were identified with C4 photosynthesis (e.g. Atriplex argentea Nutt., Andropogon scoparius Michx., Boutelou gracilis Lag., Calamovilfa longifolia Hook.). The amount of total identified C4 species in the region is much less than that from the South Dakota mixed prairie (27 species). Gramineae is the leading family with C4 photosynthesis (8 species), Chenopodiaceae ranks the second (2 species). Relatively less forb types [50 % perennial forbs (PEF) and 12 % annual forbs (ANF)] and more graminoid types (25 %) composition suggested that the rangelands in the region are relatively stable. Lacking of the knowledge on the optimal traits for PFTs classification in the region, further studies (e.g. C3 and C4 plant identification and optimal trait selection) are needed to explore the relationships between PFTs and vegetation variations, as well as land-use and climate changes.

Abstract: The meiotic chromosome numbers for 18 species of Atriplex section Obione (Chenopodiaceae) are presented. This is the first report for Atriplex abata, A. elegans, A. linifolia, A. minuscula, A. parishii, A. pueblensis, A. tampicensis, A. texana and A. thornberi. Photographs of the meiotic figures of 12 species are presented. All the species are diploid with 2n = 18, except for Atriplex argentea, A. cordulata, A. coronata and A. leucophylla tetraploids with 2n = 36. The basic chromosome number (x = 9) for the section is confirmed. Atriplex argentea, with the broadest geographic distribution, has at least two ploidy levels. All the tetraploid species occur in southwestern United States, the area of greatest diversity of the section Obione. Chromosome numbers appear to have taxonomic value and allopolyploidy might have played an important role in the evolution of the section.