''Charpentiera densiflora'' is a rare species of

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

in the family

Amaranthaceae Amaranthaceae ( ) is a family of flowering plants commonly known as the amaranth family, in reference to its type genus '' Amaranthus''. It includes the former goosefoot family Chenopodiaceae and contains about 165 genera and 2,040 species, maki ...

known by the common names dense-flowered pāpala and Nā Pali Coast pāpala. It is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the island of

Kauai Kauai (), anglicized as Kauai ( or ), is one of the main Hawaiian Islands. It has an area of 562.3 square miles (1,456.4 km2), making it the fourth-largest of the islands and the 21st-largest island in the United States. Kauai lies 73 m ...

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

, where there are 300The Nature Conservancy
/ref> to 400USFWS
Determination of endangered status for 48 species on Kauai and designation of critical habitat.
''Federal Register'' April 13, 2010. (large file) mature trees remaining. This and many other rare Kauaian plants were added to the

endangered species list On 29 January 2010, the IUCN Red List of Threatened Species identified 5220 (2754 animals, 1 fungus, 2464 plant, 1 protist) endangered species, subspecies and varieties, stocks and sub-populations. For IUCN lists of endangered species by kingdo ...

of the United States in 2010. This is a tree growing up to 12 meters tall. It occurs in forests in moist mountain gulches which are dominated by hala (''Pandanus tectorius''), a common tree of the Pacific Islands. The leaves are roughly oval in shape and up to 40 centimeters long. The

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

is a branching

panicle In botany, a panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a p ...

of flowers, each main branch bearing up to 100 flowers. Like other plants of its genus, this species is gynodioecious; most of the plants have bisexual flowers with male and female parts, but some have only female flowers.Sohmer, S. H. (1973)
A preliminary report of the biology of the genus ''Charpentiera'' (Amaranthaceae).
''Pacific Science'' 27:4 399. Some of the female parts in the bisexual flowers are abortive or nonfunctional, indicating that the species is in the middle of an

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

toward a fully dioecious system; eventually some flowers might start developing without the female parts. If the species becomes dioecious, some individuals will produce all male flowers and some will bear all female. This species has smaller seeds than any other of its genus. The tree is found only on Kauai, and mainly on the Nā Pali Coast. There are seven populations. Many of the remaining individuals are in the forests of Hoolulu Valley at around 800 feet in

elevation The elevation of a geographic location (geography), ''location'' is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational equipotenti ...

. The tree sometimes grows alongside '' Charpentiera elliptica'', and the two species sometimes hybridize. However, the rare dense-flowered pāpala does not seem to be succumbing to the problems involved in hybridization, such as

genetic pollution Genetic pollution is a term for uncontrolled gene flow into wild populations. It is defined as "the dispersal of contaminated altered genes from genetically engineered organisms to natural organisms, esp. by cross-pollination", but has come to be ...

, as evidenced by its maintaining its numbers without having its population overcome by hybrids. It is possible that ecological isolation helps protect the tree. This rare tree is threatened by a number of processes. It was probably much more widespread than it is today. Its habitat has been destroyed and degraded by

feral goat The feral goat is the domestic goat (''Capra hircus'') when it has become established in the wild. Feral goats occur in many parts of the world. Species Feral goats consist of many breeds of domestic goats, all of which stem from the wild go ...

s and

pigs The pig (''Sus domesticus''), also called swine (: swine) or hog, is an omnivorous, domesticated, even-toed, hoofed mammal. It is named the domestic pig when distinguishing it from other members of the genus '' Sus''. Some authorities cons ...

, washed out by

flood A flood is an overflow of water (list of non-water floods, or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant con ...

s, and invaded by a number of non-native plant species. It experienced damage during

Hurricane Iniki Hurricane Iniki ( ; Hawaiian: ''iniki'' meaning "strong and piercing wind") was a hurricane that struck the island of Kauai on September 11, 1992. It was the most powerful hurricane to strike Hawaii in recorded history, and the only hurricane to ...

in 1992, which led to

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

References

External links

USDA Plants Profile
{{Taxonbar, from=Q5086636 Amaranthaceae Endemic flora of Hawaii