ISA Certified Arborist Practice Exam

Which component primarily makes up the structure of hardwood trees?

1. Needles

2. Leaves

3. Broad leaves

4. Cones

The correct answer is: Broad leaves

The structure of hardwood trees is primarily made up of broad leaves. This characteristic is significant because hardwoods are defined by their broadleaf trees, which are typically deciduous, shedding their leaves annually. The broad leaves are efficient at photosynthesis due to their sizable surface area, allowing these trees to make the most of sunlight while facilitating gas exchange through stomata. In contrast to the components mentioned in the other options, needles are associated with softwood trees, which are conifers. Leaves, while present in both hardwoods and softwoods, are predominantly broad in hardwood species, making this option more specific. Cones are reproductive structures found in conifers, not in hardwood trees. Thus, broad leaves are the defining feature of hardwood tree structure, contributing to their identification and ecological role.