Final answer:
If short is a recessive trait, then when crossing two heterozygous plants, we would expect 25% of the offspring to be short.
Step-by-step explanation:
To determine the expected number of short plants, we need to know the inheritance pattern for the trait of being short. If short is a recessive trait, then we can use the Punnett square to calculate the probabilities.
If we assume a simple Mendelian inheritance with a single gene controlling the trait, and short being recessive, then when crossing two heterozygous plants, we would expect 25% of the offspring to be short. So if we plant 100 seeds, we would expect approximately 25 to be short.