What characteristic defines vascular plants?

Vascular plants are defined by the presence of specialized tissues known as vascular tissues, which are crucial for the transport of nutrients and water throughout the plant. These tissues consist of xylem and phloem: xylem transports water and dissolved minerals from the roots to the rest of the plant, while phloem distributes the products of photosynthesis, primarily sugars, from the leaves to other parts of the plant. This complex tissue system enables vascular plants to grow larger and occupy a variety of terrestrial habitats, as it efficiently supports their physiological needs.

The other options do not accurately capture the defining characteristics of vascular plants. For instance, the assertion that vascular plants do not have roots is incorrect, as many vascular plants do have roots that aid in water and nutrient absorption. Similarly, claiming that they lack specialized tissues overlooks the fundamental aspect of what makes vascular plants unique—their specialized vascular tissues. Lastly, vascular plants are not strictly aquatic; they can thrive in diverse environments, including terrestrial ecosystems. Therefore, the defining characteristic is indeed the presence of tissues specifically designed for nutrient transport.