Sanicula mariversa is a rare species of flowering plant in the carrot family

Apiaceae

The Apiaceae , commonly known as carrot or parsley family, is a group of mostly aromatic plants with hollow stems. The family is large, with more than 3,700 species spread across 434 genera, it is the sixteenth largest family of flowering plants...

 known by the common name Waianae Range black-snakeroot. 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 known only from the Waianae Mountains

Waianae Range

Waianae Range is the eroded remains of an ancient shield volcano that comprises the western half of the Hawaiian Island of Oahu...

 on the island of Oahu

Oahu

Oahu or Oahu , known as "The Gathering Place", is the third largest of the Hawaiian Islands and most populous of the islands in the U.S. state of Hawaii. The state capital Honolulu is located on the southeast coast...

. It is threatened by the degradation of its habitat. It is a federally listed endangered species

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 of the United States.

This plant produces erect, branching stems 40 to 70 centimeters long from a thick caudex

Caudex

A caudex is a form of stem morphology appearing as a thickened, short, perennial stem that is either underground or near ground level . It may be swollen for the purpose of water storage, especially in xerophytes...

. The leaves have leathery, dark green, heart-shaped or kidney-shaped blades up to 15 centimeters long by 23 wide which are palmately divided into three to five dissected lobes. 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 cluster of many tiny yellow flowers, each flower measuring only about a 0.1 centimeter long. The fruit, measuring about half a centimeter long, is covered in hooked prickles

Thorns, spines, and prickles

In botanical morphology, thorns, spines, and prickles are hard structures with sharp, or at least pointed, ends. In spite of this common feature, they differ in their growth and development on the plant; they are modified versions of different plant organs, stems, stipules, leaf veins, or hairs...

. This species is a monocarpic

Monocarpic

Monocarpic plants are those that flower, set seeds and then die. Other terms with the same meaning are hapaxanth and semelparous. The term was first used by Alphonse de Candolle....

 perennial

Perennial plant

A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...

, growing for several years, flowering and fruiting only once, then dying. The plant withers after its growing season each year and remains dormant for the rest of the year, which is probably why it was not officially collected until 1985 nor described to science until 1987. The plant was named for its residence on a ridge overlooking the ocean.

This plant grows on the Makua-Keaau and Kaluaa-Lualualei Summit Ridges of the central Waianae Mountains. The habitat is lower-elevation moist grassland. The plants grow in deep soil and in cracks in steep rock cliffs. The surrounding ground has a layer of moss

Moss

Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...

es and lichen

Lichen

Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...

s. The area has been invaded

Invasive species

"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....

 by non-native species of grass

Grass

Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...

es including soft chess (Bromus mollis) and annual fescue

Vulpia

Vulpia is a genus of grasses which are known as fescues; Vulpia is sometimes considered a subset of the main fescue genus, Festuca. Many of these fescues are considered noxious weeds in places where they are not native...

 (Vulpia spp.). Another source of habitat degradation is the mountains' population of feral goat

Feral goat

The feral goat is the domestic goat when it has become established in the wild. Feral goats occur in Australia, New Zealand, Ireland, Great Britain, Hawaii, the Galapagos and in many other parts of the world...

s, which scale the slopes, breaking up the soil and causing erosion

Erosion

Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

.

As of 2006 there were 18 mature individuals and 170 immature plants remaining.