Learn from the best Johnny Appleseed and Smokey the Bear at todays Arbor Day Celebration. The man who planted apple trees across America and the wildfire-fighting bear will lead activities including hikes, talks by nature experts, live music, demos by crafters and papermakers, storytellers, a zip line and a rope bridge. Get there early and you might snag a free seedling (while supplies last). Get there really early and join the 7 a.m. Breakfast with the Birds guided hike. (Free to $10.) Arbor Day activities are scheduled from 10 a.m. to 4 p.m. Houston Arboretum, 4501 Woodway Drive. For information, call 713-681-8433 or visit www.houstonarboretum.org. Free.