Two native geranium relatives grow in Koolau Gap, _N. ovatifolium_ (A. Gray) Degener & Greenwell and its variety _superbum_. The latter is common on the trail to Waikau not far from the foot of Leleiwi Pali.
One of the common plants growing on the crater floor is the exotic pink-flowered _G. carolinianum_ var. _australi_ (Benth.) Fosberg whose pointed fruiting bodies give it the common name, _cranesbill_.
HAWAIIAN HOLLY, KAWA’U, _Ilex anomala_ Hook and Arn. The forest growing on the talus behind the Paliku cabins is the finest within the crater. A striking tree of this association is the Hawaiian holly that has dark, shiny, oval leaves with conspicuous networks of slightly depressed veins that make identification easy. Dense panicles of small, white flowers are followed by shiny, black drupes, like Christmas holly “berries.” The genus is that of the English holly. Curiously, the scientific name has been locally corrupted to _ileck_.
OLOMEA, _Perrottetia sandwicensis_ A. Gray. A native shrub or small tree belonging to the same family as the bittersweet of the continent. The numerous tiny, round, red fruits, borne in panicles, suggest the relationship. The bright red venation of leaves and petioles make the plant easily recognized. I know of no plants within the park, but found many trees a thousand feet below the park boundary in Keanae Valley.
A’AL’II, _Dodonaea eriocarpa_ Smith. Fig. 8. This is a common shrub in several varieties along the highway and in the western end of the crater. At Paliku and Kaupo Gap it becomes a tree up to 20 feet high and 8 inches in diameter. Its flowers are inconspicuous but clusters of dry, reddish fruit-capsules contrast, flower-like, with the surrounding green foliage. The fruits, abundant from July to September, are used for leis and dry bouquets. The hard brown heartwood was used for spears, _pololu_, daggers, _pahoa_, and other implements.
BEGONIA—PUAMAKANUI, _Hillebrandia sandwicensis_ Oliv. (See illustration p. 53.) The only native begonia, found in wet ravines often by waterfalls. It grows profusely at Koolau a mile below Holua Cabin at the foot of the rain-drenched _pali_. This succulent herb has a tuberous rhizome, unbranched, slender stems, and hairy, toothed leaves 4-10 inches in diameter. From June to August it bears sprays of bright, pink and white flowers. This is one of the floral treasures of Hawaii.