CYTOGENETIC RELATIONSHIPS BETWEEN THE ERAGROSTIS-CURVULA AND ERAGROSTIS-LEHMANNIANA COMPLEXES

The meiotic chromosome pairing behavior of hybrids between diploid (2n = 2x = 20) and tetraploid (2n = 4x = 40) cytotypes of weeping, beer, and lehmann lovegrasses was analyzed to better understand relationship s within and between the Eragrostis curvla and Eragrostis lehmanniana complexes. Within the E. curvla complex, the mean chromosome pairing b ehavior of the diploid weeping x tetraploid weeping hybrid was 8.68 I + 8.60 II + 1.37 III; diploid beer x diploid weeping hybrids was 0.36 I + 9.82 II; and diploid boer x tetraploid weeping hybrids was 7.05 I + 6.83 II + 3.10 III. Thus beer and weeping lovegrasses are closely re lated and have similar genomes, Doer lovegrass appears to be correctly classified as a botanical variety off curvla. In comparing the two co mplexes, tetraploid boer was crossed with diploid lehmann and a tetrap loid cold-hardy lehmann (CHL) type. The mean pairing behavior of the t etraploid boer x diploid lehmann hybrids was 9.16 I + 9.03 II + 0.92 I II and of the tetraploid boer x CHL hybrids was 1.50 I + 18.24 II + 0. 01 III + 0.51 IV. Lehmann, particularly the CHL type, and burr lovegra sses appear to have similar genomes and thus a common ancestry. Althou gh members of these two complexes have the same genomic constitution a nd could be considered one complex, data from other research indicate that they are genetically isolated and are best treated as separate sp ecies. Those hybrids with an apomictic male parent were facultative di plosporous apomicts. However there was evidence of aposporous developm ent in some ovules of the diploid boer x tetraploid weeping hybrid.