The west-facing upper slopes of Haleakala are locally called "Upcountry." This region is responsible for much of Hawaii's produce -- lettuce, tomatoes, strawberries, and sweet Maui onions for starters. As you drive along you'll notice cactus thickets mingled with purple jacaranda, wild hibiscus, and towering eucalyptus trees. Upcountry is also fertile ranch land; cowboys still work the fields of the historic 20,000-acre Ulupalakua Ranch and the 32,000-acre Haleakala Ranch. Keep an eye out for pueo, Hawaii's native owl, which hunts these fields during daylight hours.
A drive to Upcountry Maui from Wailea or Kaanapali can be an all-day outing if you take the time to visit Tedeschi Vineyards and the tiny town of Makawao. You may want to cut these sidetrips short and combine your Upcountry tour with a visit to Haleakala National Park. If you leave early enough to catch the sunrise from the summit, you'll have plenty of time to explore the mountain, have lunch in Kula or at Ulupalakua Ranch, and end your day with dinner in Makawao.