While visiting the Kona side of Hawai’i, I noticed a low shrubby plant with stunning white flowers that had many long stamens. Can you tell me what its name is (both the scientific name and common name)? Is it something that could grow in a Pacific Northwest climate?
The plant in your picture is Capparis sandwichiana, or Hawaiian caper. Your description pinpoints one of the most striking features of this shrub, its numerous, showy stamens. In Hawai’i it is called maiapilo or pua pilo. According to A Tropical Garden Flora by George Staples and Derral Herbst (Bishop Museum, 2005), it prefers the hot sun and salt spray of coastal coral flats, rocky cliffs, or exposed lava flows further inland. It is used in rock gardens, and as a ground cover in seaside gardens, and on slopes and banks. The plant has traditional medicinal uses for treating skin, bone, and joint injuries. The name pua pilo, ‘stinking flower,’ is a bit of a misnomer. The flowers, which open at sunset and last only one night, are sweetly fragrant. It is the cucumber-shaped ripe fruit and the leaves (when handled) that are malodorous. It does not produce the capers that are known for their culinary uses. Those capers come from the buds of Capparis spinosa.
According to the United States Botanic Garden, Capparis sandwichiana is vulnerable in its native range (Endangered Species status) due to development of the Hawaiian coast and lowlands.
Neither species of Capparis would thrive in the Pacific Northwest. Capparis sandwichiana is suitable for Zone 11. Capparis spinosa, a Mediterranean species, is Zone 8-10, but at zone 8b, we are a marginal location for this plant. Pacific Northwesterners who yearn to make their own edible capers can try pickling Nasturtium seeds, as described in this Oregonian article (August 2, 2009, Vern Nelson). I suspect, however, that it is the flowers that captured your imagination!