Am. Powell, 2ND-GENERATION EXPERIMENTAL HYBRIDIZATIONS IN THE ECHINOCEREUS X LLOYDII COMPLEX (CACTACEAE), AND FURTHER DOCUMENTATION OF DIOECY IN E-COCCINEUS, Plant systematics and evolution, 196(1-2), 1995, pp. 63-74
Artificial second generation and backcross hybrids involving Echinocer
eus dasyacanthus (Texas rainbow cactus), E. coccineus (a species of cl
aret-cup cactus), and E. X lloydii (Lloyd's hedgehog cactus) were exam
ined for morphological and reproductive characteristics. The hybrids g
rew from seed to flower in about four years, and they exhibited high f
ertility as measured by pollen stainability, crossability, and fruit-s
et. A rare breeding system in Cactaceae, dioecy, was further examined
in E. coccineus, using field and controlled pollination tests. Functio
nal dioecy was documented for E. coccineus in Trans-Pecos Texas. Al re
sults suggested that E. X lloydii in eastern Pecos County, Texas, is a
complex and dynamic population probably comprising first and later ge
neration hybrids, including backcross hybrids. The experimental hybrid
izations also tended to support the occurrence of introgression into b
oth putative parental species.