Abstract
A systematic investigation of the Bothriochloa saccharoides complex was made. Included in the study were the taxa B. exaristata (Nash) Henrard, B. imperatoides (Hackel) Herter, B. laguroides (DeCandolle) Herter, B. reevesii (Gould) Gould, B. saccharoides (Swartz) Rydberg, B. saccharoides var. longipaniculata (Gould) Gould, Andropogon saccharoides subsp. parvispiculus Hitchcock, B. saccharoides subvar. paucirameus Hackel, B. saccharoides var. pulvinata (Gould) Gould, and B. saccharoides var. torreyana (Steudel) Gould. Analysis of morphology by principal components revealed three major phenetic clusters. Two of the clusters, representing the taxa imperatoides and parvispicula, formed homogenous, well defined groups of specimens clearly distinct from the others. The third cluster represented the B. saccharoides complex, and included all remaining taxa. The phenetic analysis showed the B. saccharoides complex to be composed of a series of intergrading subunits. The taxon exaristata was displaced to one extreme of the cline, with saccharoides and reevesii at the other. Laguroides, longipaniculata, pulvinata, and torreyana occupied intervening positions. All members of the Bothriochloa saccharoides complex are sexual in nature, with allogamous or autogamous reproduction. Hybridization studies suggest incomplete reproductive isolation between the members of the complex. Crosses of exaristata x torreyana, each hexaploid, provided evidence supporting the hypothesis that the duodecaploid longipaniculata originated by such an event. Morphologic evidence suggests that this is a current process among South American populations of these taxa. Torreyana x laguroides crosses also produced viable seed. Cytological studies confirmed previous chromosome counts of 2n = 60 for the taxa exaristata, imperatoides, laguroides, longipaniculata, pulvinata, reevesii, and torreyana, and 2n = 120 for the taxa longipaniculata and reevesii..
Allred, Kelly Wayne (1979). Systematics of the Bothriochloa saccharoides complex (Poaceae). Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -140537.