First Page


Last Page



Allozyme data were used to evaluate the genetic status of a rare endemic sunflower from Texas, Helianthus praecox ssp. hirtus. Comprising approximately 200 plants, the taxon is presently known from a single population in the Carrizo Springs region of Southern Texas. Electrophoretic examination of 17 enzyme loci revealed that ssp. hirtus is genetically similar to, but distinct from, the two more widespread subspecies of H. praecox: ssp. praecox and ssp. runyonii. Levels of genetic variation in the single population of ssp. hirtus (P = 0.4 7, A = 1.88, and H = 0.17) are similar to those observed for other populations in the H. praecox complex (P = 0.44, A = 1.68, and H = 0.15). Thus, if isozyme loci are used as the one indicator of genetic variation in ssp. hirtus, it cannot be concluded that this taxon is endangered due to a loss of genetic variation. Nevertheless, due to the highly endemic status of ssp. hirtus serious conservation efforts must be made to ensure the long-term preservation of this taxon. Several management recommendations are given herein.

Rights Information

© 1989 Loren H. Rieseberg, Michael F. Doyle

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Included in

Botany Commons