Chromosome studies on the Carex salina complex (Cyperaceae, section Cryptocarpae) in Northeastern North America.

Chromosome studies on Carex paleacea Wahl., C. nigra (L.) Reichard, and C. aquatilis Wahl. in Northeastern North America.

“…These larger chromosomes ap peared to be nucleolar ones. We reported the same situation in the Carex sauna complex (Cayouette and Morisset 1986). Chromosome sizes in C. nigra were much more uniform than in the other two species (Table 3; Figs.…”

“…21). In this case, instead of three microspores degen erating as usual, only two were degenerating and the other two had fused, giving a number of chromosomes approximately twice the haploid number, such as reported from Carex recta (Cayouette and Morisset 1986). However, the most commonly observed unreduced pollen grains of C. aquatilis were formed from diads, with the two degenerating cells fused into one, and the other two microspores forming an unreduced pollen grain (Figs.…”

“…The succession of meiotic stages within the same staminate spike, was always from the bottom to the apex, as in the Carex sauna complex (Cayouette and Morisset 1986). Upper spikes matured prior to the lower ones.…”

“…The trivalent was an hetero morphic chain (Fig. 5) or a frying-pan, such as observed in the C. sauna complex (Cayouette and Morisset 1986).…”

“…We supposed that, if there are four homologous chromosomes in a given plant, they can occur at metaphase I either as a quadrivalent or as a trivalent plus an univalent, and so on (see Cayouette and Morisset 1986, for more details). The various patterns of meiotic associations in metaphase I cells of a given plant could thus be summarized as a single pattern of maximum meiotic association, i.e.…”