The northern catalpas (Catalpa speciosa) are blooming. These guys are native to the Ozarks but are fairly common here because they were the hot landscaping trees of the mid 19th century. They have huge heart-shaped leaves and gorgeous clumps of large white flowers. If you look down a flower you can see they are marked like a bee landing strip. Also, if you look at the underside of the leaves you can see little yellow spots. These are extra floral nectaries. When catalpa trees suffer too much insect damage, they will produce nectar here to encourage predatory ants to protect the tree.