Answer:
Barley
Step-by-step explanation:
Barley is a widely distributed cereal plant belonging to the genus Hordeum, of the grass family, having awned flowers that grow in tightly bunched spikes, with three small additional spikes at each node.
Were there any crops that appeared in both the Old and New World before the Columbian exchange?
Cotton. Genetic data indicates transoceanic interspecific migration and hybridization between different species.
Old World cotton is represented by the A genome (cultivated in ancient Africa and Asia). In the New World, the D genome first appeared. All cultivated species now are allopolyploids, and they all come from the New World. Take note of how much bigger the current species' bolls are! (Cotton is also a fascinating illustration of interspecific migration and hybridization across oceans!)
Sweetpotato
Sweetpotato likely also made a transoceanic voyage.
The most recent papers suggest natural dispersion is sufficient, but sweetpotato has also been used to suggest the Polynesians made it to South America.
The sweet potato visited Southeast Asia three times on its own. It was presumably first used about 1100 A.D. by the Polynesians (red). While other types from the Americas were imported by the Spanish (blue) and Portuguese (yellow) about 1500.
Thank you,
Eddie