Katherine again writes today’s entry:
Today, we have a beautiful image of Hibiscus waimeae subsp. hannerae thanks to Anna Kadlec via the Botany Photo of the Day Submissions Forum.
Hibiscus waimeae has two subspecies (sometimes designated varieties): Hibiscus waimeae subsp. hannerae and Hibiscus waimeae subsp. waimeae. Today’s featured subspecies is generally smaller overall (including smaller flowers) when compared to the subspecies waimeae, though it has larger leaves. Hibiscus waimeae subsp. hannerae is endemic to Hawaii, and known by the Hawaiian names: Aloalo, Koki’o kea, and Koki’o ke’oke’o, In English, the taxon is commonly known as Kauai white hibiscus, minature Hawaiian white hibiscus, small Kauai white hibiscus, and white Kauai rosemallow. Native Plants Hawaii (see previous link) notes that the genus name stems from “hibiscos, Greek for ‘mallow’, and the epithet waimeae refers to the Waimea Canyon, Kaua’i where this species is found.” That reference also states that Hibiscus waimeae subsp. hannerae blooms year round, although sporadically (often ceasing during winter or early spring), and is unusual among hibiscus in that it is one of only two species (both native to Hawaii) to have fragrant flowers.
According to the U.S. National Tropical Botanical Garden (NTBG) page for Hibiscus waimeae subsp. hannerae, these single flowers last only one day and are “white when open in [the] morning and fade to pink in the afternoon” with a staminal column that is pink to crimson. Easily grown in cultivation (it was previously used as decoration near huts), the taxon is considered endangered. It occurs only in Kaua’i’s northwestern valleys of Hanakapi’ai, Limahuli, and Kalihi Wai at elevations of 240 – 1,200m (800 – 3,900ft) (see previous link). Its rarity is in part due to the ease with which Hibiscus waimeae subsp. hannerae hybridizes, and, according to the IUCN Red List, partly due to habitat being “frequently damaged by feral pigs and invaded by introduced plants”. The IUCN Red List also notes that the population on Kalihi Wai is seemingly extirpated.