Cytogeography and Phylogeny of the North American Species of Verbena

Abstract

Lewis, Walter H., and Royce L. Oliver. (Stephen F. Austin State Coll., Nacogdoches, Texas.) Cytogeography and phylogeny of the North American species of Verbena. Amer. Jour. Bot. 48(7): 638–643. Illus. 1961.—Chromosome numbers of 26 Verbena species in North America, separable into 2 series, are reported. The x = 5 series has no diploid representative, few tetraploids, and numerous widespread hexaploid species, while the x = 7 series has many pandemic diploid species and few tetraploid and hexaploid taxa. When compared with the data available for the South American verbenas, these frequencies and distributions were found to be almost opposite. The origin of the 2 groups from an x = 6 prototype followed by ascending and descending aneuploidy is suggested. Migration via tropical land bridges is proposed to explain the occurrence of both groups in the 2 continents. The following taxa are proposed: subgenus Verbenaca (Schauer) Lewis, and subgenus Glandularia (Gmelin) Lewis.

IRIDOIDS IN VERBENA

“…Perry (1933) and Lewis and Oliver (1961) concluded from morphological and cytological differences that the subgenera Verbenaca and Glandularia had been separate for a long time. Two of them contained griselinoside, while V. litoralis had an unknown compound, which according to the 1H NMR spectrum was an iridoid glucoside.…”

“…Six species from the group Leptostachyae were investigated, and all contained mixtures of cornin and hastatoside in varying proportions. Perry (1933) and Lewis and Oliver (1961) concluded from morphological and cytological differences that the subgenera Verbenaca and Glandularia had been separate for a long time. The differences found in the present study support this £.…”

“…Most authors agree to a division of the genus into two distinct sections, Verbenaca and Glandularia (see Perry, 1933). Partly due to the consistent difference in basic chromosome number (7 in Verbenaca and 5 inGlandularia), Lewis and Oliver (1961) preferred to raise these taxa to subgeneric rank.…”

Phylogeny and biogeography in Solanaceae, Verbenaceae and Bignoniaceae: a comparison of continental and intercontinental diversification patterns

“…In total, approximately 65 species (c. 7.5% of New World diversity) occur further than c. 35°north or south of the equator. Glandularia, Verbena L. (Verbeneae) and Aloysia (Lantaneae) all exhibit amphitropical disjunctions of several thousand kilometres between arid North and South America, a pattern observed in numerous unrelated groups, suggesting long-distance dispersal (Lewis & Oliver, 1961;Solbrig, 1972;Yuan & Olmstead, 2008a;P. Lu-Irving & R. G. Olmstead, unpublished), although there is evidence for Verbena suggesting that a dispersal route along the Andes, where seasonal dry forests have existed for a long time in a series of discontinuous patches (Pennington, Lavin & Oliveira-Filho, 2009), may be responsible V.…”

Cytomorphological Studies on Some North Indian Members of the Family Verbenaceae

“…However the chromosome number of n=6 and 7 both are new to Indian populations. The species is well known to have intraspecific cytotypes of x=7: 2n=14 and 28 from Indian populations and 2n=14, 28, 42 and 70 from outside India (Lewis and Oliver 1961).…”