Final answer:
Cacti is the streamside vegetation that is particularly prominent in arid regions.
Step-by-step explanation:
The streamside vegetation that is particularly prominent in arid regions is cacti. Cacti have evolved various adaptations to survive in dry environments, such as thick and fleshy stems to store water, and spines instead of leaves to reduce water loss. They are well-suited to arid regions because they can minimize water loss and thrive in conditions where other plants struggle.