The Pea. The Pewee.

To tell the Pewee from the Pea, Requires great per-spi-ca-city. Here in the pod we see the Pea, While perched close by is the Pewee;

The Pea he hears the Pewee peep, While Pewee sees the wee Pea weep, There'll be but little time to see, How Pewee differs from the Pea.