Here's how to figure out the offspring of crossing two heterozygous Tt tall plants:

Understanding the Terms:

* Heterozygous: Means the plant has two different alleles (versions) of a gene. In this case, "Tt" means one allele is dominant (T for tall) and one is recessive (t for short).

* Tall: The dominant trait, meaning a plant with at least one "T" allele will be tall.

* Short: The recessive trait, meaning a plant needs two "t" alleles to be short.

Punnett Square:

We use a Punnett square to predict the possible offspring:

```

T t

T TT Tt

t Tt tt

```

Interpreting the Results:

* TT: Tall (1 out of 4 possibilities)

* Tt: Tall (2 out of 4 possibilities)

* tt: Short (1 out of 4 possibilities)

Conclusion:

When you cross two heterozygous Tt tall plants, you get a 3:1 phenotypic ratio:

* 3 Tall plants (TT and Tt)

* 1 Short plant (tt)