Haplostachys haplostachya is a rare species of flowering plant in the mint family

Lamiaceae

The mints, taxonomically known as Lamiaceae or Labiatae, are a family of flowering plants. They have traditionally been considered closely related to Verbenaceae, but in the 1990s, phylogenetic studies suggested that many genera classified in Verbenaceae belong instead in Lamiaceae...

 known by the common name honohono. It is endemic to Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

, where it is now limited to the island of Hawaii

Hawaii (island)

The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...

 and has been extirpated

Local extinction

Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...

 from Kauai

Kauai

Kauai or Kauai, known as Tauai in the ancient Kaua'i dialect, is geologically the oldest of the main Hawaiian Islands. With an area of , it is the fourth largest of the main islands in the Hawaiian archipelago, and the 21st largest island in the United States. Known also as the "Garden Isle",...

 and Maui

Maui

The island of Maui is the second-largest of the Hawaiian Islands at and is the 17th largest island in the United States. Maui is part of the state of Hawaii and is the largest of Maui County's four islands, bigger than Lānai, Kahoolawe, and Molokai. In 2010, Maui had a population of 144,444,...

. It has been on the United States' endangered species list since 1979.

Haplostachys haplostachya is probably the only one of the five Haplostachya species that is not now extinct

Extinction

In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

, so it may be the only member of a monotypic genus. There are now fewer than 20,000 individual plants in scattered fragmented populations remaining at Kipukakalawamauna on the Pohakuloa Plateau, the site of the Pohakuloa Training Area

Pohakuloa Training Area

Pōhakuloa Training Area is located on the island of Hawaii in the high plateau between Mauna Loa, Mauna Kea and the Hualālai volcanic mountains...

. At one time, the plant was not uncommon on the slopes of Mauna Loa

Mauna Loa

Mauna Loa is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaii in the Pacific Ocean, and the largest on Earth in terms of volume and area covered. It is an active shield volcano, with a volume estimated at approximately , although its peak is about lower than that...

 and Mauna Kea

Mauna Kea

Mauna Kea is a volcano on the island of Hawaii. Standing above sea level, its peak is the highest point in the state of Hawaii. However, much of the mountain is under water; when measured from its oceanic base, Mauna Kea is over tall—significantly taller than Mount Everest...

. Destruction of the habitat by feral

Feral

A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...

 ungulate

Ungulate

Ungulates are several groups of mammals, most of which use the tips of their toes, usually hoofed, to sustain their whole body weight while moving. They make up several orders of mammals, of which six to eight survive...

s, military construction, consequences of military activity such as dust and fires, introduced plant species

Introduced species

An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

, and deforestation

Deforestation

Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....

 have fragmented

Habitat fragmentation

Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...

 the plant's distribution and reduced it to its present low numbers. This fragmentation has also led to physical

Isolating mechanisms

Isolating Mechanisms are features of behavior, morphology, or genetics which serve to prevent breeding between species. Reproductive isolation of populations is established. It is particularly important to the biological species concept, as species are defined by reproductive isolation...

 and reproductive isolation

Reproductive isolation

The mechanisms of reproductive isolation or hybridization barriers are a collection of mechanisms, behaviors and physiological processes that prevent the members of two different species that cross or mate from producing offspring, or which ensure that any offspring that may be produced is not...

 in the smaller, more isolated populations, causing a genetic bottleneck.

This is a perennial shrub which grows to 1.5 meters tall. The square stems are lined with fleshy, woolly, somewhat heart-shaped leaves. The inflorescence

Inflorescence

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

 is a showy raceme

Raceme

A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...

of fragrant, woolly white flowers each up to 2 centimeters long. The herbage lacks the minty taste and scent of other mints.

Though there are few wild specimens left, the honohono is cultivated and kept as a garden plant in Hawaii.