This is a great, less-thirsty plant for your hot, dry garden, with large, thick, hairy leaves to conserve life-giving moisture and milky sap to protect it from hungry animals.

Although crown flower is not as common in island gardens as it once was, you still see lots of it in hot, lowland areas like Nanakuli, Wai'anae and Waimanalo on O'ahu; Kamiloloa and Kalama'ula on Moloka'i; Kawaihae and Puako on the Big Island; Lahaina and Kihei on Maui; and Kekaha and Waimea on Kaua'i.

Both color forms of crown flower can be made into lei. Either the whole flower is used, or the crowns or bases only are used to make more complex lei. They have a mild fragrance and are fairly lightweight to wear.

As kids we loved to watch monarch butterfly caterpillars chomp the leaves, grow bigger and finally crawl away to a nearby plant to transform themselves into a green chrysalis decorated with gold. The chrysalis "before our very eyes" gradually turned orange and black with a wing pattern, and one day a limp-winged, new butterfly emerged. This was one of those miracles of small-kid time in Hawai'i.

On a side note, there are fewer monarch butterflies in Hawai'i today because newly introduced insects parasitize the caterpillars, and bulbul birds (another pestiferous illegal introduction) gobble up the butterflies. Most birds find monarch butterflies distasteful because of their feeding on crown flowers and other milky-sapped plants in the milkweed family, but not the bulbul.

All parts of the crown flower have white milky sap. You do not want to get this sap in your eyes while picking flowers or trimming the plant.

As mentioned previously, crown flowers are in the milkweed family, asclepiadaceae. Known in Latin as Calotropis gigantea, they are related to hoya the wax vine, stephanotis or pua male, pakalana, and milkweeds. The Hawaiians gave it the name pua kalaunu.

Crown flowers are a bit tricky to get started. You can grow them from branches or buy them from a nursery. Plant crown flower in full-sun garden areas.

Don't miss the annual Halawa Xeriscape Garden Open House and Unthirsty Plant Sale, an annual fund-raiser. There's plenty to do at this event, including garden tours, workshops and craft displays. The free event takes place from 9 a.m. to 3 p.m. tomorrow at the Halawa Xeriscape Garden on 'Iwaena Street.