Chromosome Numbers in North American Loranthaceae: (Arceuthobium, Phoradendron, Psittacanthus, Struthanthus)

Abstract

Chromosome numbers are reported from 67 populations of 36 taxa, mostly in Phoradendron. The basic number is 14 in Phoradendron and probably also in Arceuthobium. The 4 species of Struthanthus for which chromosome numbers are recorded suggest that the basic number is 8. Numbers of n = 8 and n = 10 have been reported for Psittacanthus. In Phoradendron the 22 taxa examined are all diploid, although 1 instance of polyploidy was discovered. Objects interpreted as supernumerary chromosomes were discovered in a number of species of Phoradendron; no evidence of sex chromosomes previously reported in Phoradendron was observed. The Loranthaceae have chromosomes comparable in size to the largest in the plant kingdom.

Mitotic karyotype stability and meiotic irregularities in the families Loranthaceae Juss. and Viscaceae Miq

“…Among the Loranthaceae, the Struthanthus species here investigated, as well as all other registers from Argentina (Covas 1949), Mexico (Wiens 1964) and Costa Rica (Barlow and Wiens 1971), displayed n=8. In Psittacanthus, the three species examined in the present work had n=8, with small differences in chromosome morphology revealed only by their ideograms.…”

“…The three species here investigated and other 36 species of Phoradendron displayed n=14, one had n=27, and another had n=28 (Wiens 1964;Wiens and Barlow 1971). We observed a marked reduction in the size of some chromosomes in two of the three species analysed, suggesting the existence of structural changes within these karyotypes.…”

“…We observed a marked reduction in the size of some chromosomes in two of the three species analysed, suggesting the existence of structural changes within these karyotypes. Wiens (1964) and Barlow and Martin (1984) noted the occurrence of B chromosomes in this genus, which is also indicative of karyotypic rearrangements (Puertas 2002). A rare and extreme case of structural changes is observed in several species of Viscum, where heterozygosity for large chromosomal interchanges are associated with a complex sexdetermining chromosome system and dysploid chromosome numbers (Wiens and Barlow 1979;Aparicio 1993).…”

“…In Psittacanthus, the three species examined in the present work had n=8, with small differences in chromosome morphology revealed only by their ideograms. Eight other species have n=8, two have n=10 (Covas and Schnack 1946;King 1961;Wiens 1964;Barlow and Wiens 1971), and P. calyculatus (DC.) D. Don.…”

“…Most contributions to the cytology of Loranthaceae and Viscaceae were done by Barlow and Wiens (Barlow 1963;1964a;Wiens 1964;1968;1975;Barlow and Wiens 1971;Wiens and Barlow 1971), who studied a large number of Australian, North American, and African species. The use of non-conventional karyological techniques is restricted to the studies of Martin (1983) and Barlow and Martin (1984), who examined the DNA content of 56 Australian species, and the C-band pattern of some of them.…”