''Hillebrandia sandwicensis'' is a species of a herbaceous

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wid ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

native to some of the Hawaiian Islands. Common names include akaakaawa and pua maka nui. The genus name honors the German physician

William Hillebrand Wilhelm or William Hillebrand (November 13, 1821 – July 13, 1886) was a German physician. He practiced medicine in several different countries, including for over 20 years in the Hawaiian islands. In 1850, Hillebrand lived at what is now Fost ...

Description

In terms of morphology, ''H. sandwicensis'' is similar to ''Begonia'', but differences in flower structure, pollen morphology, and fruit separate the two genera. It produces

tubers Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing s ...

, to which above-ground parts of the plant die back to after producing fruit in the summer. The seeds are very small. Plants regrow in January. It blooms from February to June. It is monoecious, with succulent branches.

Taxonomy

It is classified in the family Begoniaceae and is the only species in the genus ''Hillebrandia''; indeed, it is the only one of the 1900 or so species in the family Begoniaceae ''not'' to be a member of the genus ''

Begonia ''Begonia'' is a genus of perennial flowering plants in the family Begoniaceae. The genus contains more than 2,000 different plant species. The Begonias are native to moist subtropical and tropical climates. Some species are commonly grown ind ...

''. It is the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to the rest of its family. The time of the split precedes the oldest above-water Hawaiian Island (

Kure Atoll Kure Atoll (; haw, Hōlanikū, translation=bringing forth heaven; haw, Mokupāpapa, translation=flat island, label=none) or Ocean Island is an atoll in the Pacific Ocean west-northwest of Midway Atoll in the Northwestern Hawaiian Islands ...

) by an appreciable period of time. This raises the question as to how a monotypic genus got to a remote island chain considerably younger than itself. It has been proposed that, even though forested ravines are not particularly windy, ''Hillebrandia'' island-hopped down the

Hawaiian – Emperor seamount chain Hawaiian may refer to: * Native Hawaiians, the current term for the indigenous people of the Hawaiian Islands or their descendants * Hawaii state residents, regardless of ancestry (only used outside of Hawaii) * Hawaiian language Historic uses * ...

(then islands) via the wind often enough to colonize each island in turn, a process aided by a Cenozoic climate allowing it to live at lower altitudes than today, regardless of where the genus originated from. ''Hillebrandia'' may also be younger than previous estimates.

Distribution and habitat

It is found in humid ravines covered with forest at altitudes of 900–1800 meters. Additionally, ''H. sandwicensis'' is the only member of its family natively found in the Hawaiian Islands. ''H. sandwicensis'' is currently found only on the islands of Maui, Molokai, and Kauai. It is

locally extinct Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

Oahu Oahu () ( Hawaiian: ''Oʻahu'' ()), also known as "The Gathering Place", is the third-largest of the Hawaiian Islands. It is home to roughly one million people—over two-thirds of the population of the U.S. state of Hawaii. The island of O� ...

, and does not occur on the Big Island. Despite an abundance of suitable habitat, the species is localized and uncommon. It has recently been getting rarer, but despite this, it is not (as of 2020) listed on the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of nat ...

Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...

.Using th
Red List website's search function
yields no hits for the word "''Hillebrandia''" However, a 1999 document from the American

Fish and Wildlife Service The United States Fish and Wildlife Service (USFWS or FWS) is an agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats. The mission of the agency is "working with othe ...

did list ''H. sandwicensis'' as one of 202 "Other Species of Concern".

References

External links

''Hillebrandia sandwicensis''.
The Nature Conservancy. {{Taxonbar, from=Q2709252 Begoniaceae Monotypic Cucurbitales genera Endemic flora of Hawaii Succulent plants Taxa named by Daniel Oliver