Interspecific hybridization between Emex australis and E. spinosa.

Emex australis and E. spinosa growing in mixed populations in the field hybridize readily so that more than 50% of the progeny of E. australis and 0.5% of the progeny of E. spinosa may be interspecific hybrids. These hybrids show irregular meiosis. low pollen stainability, and a high degree of sterility when self-pollinated. However. they appear to backcross readily to either parent to form viable seed. It is suggested that these conditions may open the way for the development, through introgressive hybridization, of new races or forms in Australia which combine the broad adaptability of E. australis with the enhanced weed potential in cereals of E. spinosa.