Final answer:
An organism with a set of chromosomes from two different species is allodiploid, a type of polyploidy which yields robust plant varieties.
Step-by-step explanation:
An organism that has one set of chromosomes from two different species is best described as a allodiploid. Allodiploidy is a form of polyploidy where the additional sets of chromosomes come from different species. This is different from autopolyploidy, where all the chromosome sets come from a single species. Polyploid plants are larger and more robust than euploids, which have the normal number of chromosome sets for their species.