Seeds are smooth and dark brown with a large tan attachment scar, the whole seed resembling an eye. Seeds have a prickly husk or covering and are poisonous to humans and livestock. Buckeyes are some of the first trees to leaf out in spring. Trees are most frequently found along river bottoms and streambanks. Usually low-branched, buckeye is shade-tolerant, and will form long straight boles if grown in dense stands of trees. Flower clusters are large, greenish-yellow, and appear in spring.