# Glochidion marianum

Glochidion marianum (Chamorro: CHosgu or Åbas duendes; Pohnpeian: luhwikitoh lol) is a species of plant in the family Phyllanthaceae that is endemic to the islands of Guam and the Caroline Islands.

## Description

Glochidion marianum is a small shrubby tree, rarely up to 5 metres (16 ft), with trunks seldom over 10–20 cm (3.9–7.9 in) diameter.
* Leaves: glabrous, elliptical or oblong-elliptical simple leaves are 5–15 cm (2.0–5.9 in) long and 3–8 cm (1.2–3.1 in) broad. Leaves are arranged alternate distichous on the stems by short petioles (1–3 mm (0.039–0.118 in)). New leaves are red or deep scarlet, producing a crown with striking appearance when numerous; mature leaves are medium green, but more pale underneath.
* Wood: fine grained, tough, and red tinted.
* Flowers: Glochidion marianum is a monoecious tree, with separate male and female flowers on the same plant. Flowers are minuscule, and color pale yellow-green. Female calyx is longer than the male's. Calyx consists of 2 larger and 3 smaller sepals, but no petals. Male flowers have 3 short-columnar anthers. Female flowers have a mostly 5-locular glabrous ovary, with styles forming a slender subulate column.
* Fruits: Fruits are globose capsules, or slightly pentagonal, glabrous, with 5 (or sometimes 6) loculi. Immature capsules are light green, becoming yellow when mature, then dark brown. Each of the dehiscent locules contains 2 bright orange or orange-brown seeds. Fruits are said to resemble a mallow fruit or Dutch cheese.
* Miniscule flowers. Dededo, Guam
* Seeds inside mature fruit. Dededo, Guam.
* Unripe fruit. Dededo, Guam
* Stem and leaves. Dededo, Guam

## Distribution and habitat

Glochidion marianum grows both in the volcanic soils of southern Guam, as well as the limestone that is typical of northern Guam. However, no distinctive variants or regional differences have yet been described.
Glochidion marianum is noted to favor abandoned clearings and edges, as well as the open savannas of southern Guam, although it can also be found in the understory of the limestone forest.

## Ecology
### Invertebrates

Most Glochidion species are known to have a mutualistic relationship with moths of the genus Epicephala. However, no Epicephala moth has yet been described for Glochidion marianum.
Several species of insect have been recovered on Guam only from Glochidion marianum, mostly from collections before World War II:
* a jumping plant louse (Trioza guama)
* a true weevil (Swezeyella muscosa)
* a jewel beetle (Chrysodema ventralis)
* a leafhopper (Tartessus ochraceus)
Other insects endemic to the Mariana Islands that have been observed on Glochidion marianum on Guam include: a fungus weevil (Notioxenus fulgidus), a leaf beetle (Phytorus lineolatus), a bee (Halictus swezeyi), a bird grasshopper (Valanga excavata), a leafhopper (Tartessus swezeyi), a chalcid wasp (Cirrospiloideus guamensis), a true weevil (Trigonops inaequalis), a jewel bug (Calliphara munda),, a sap beetle (Haptognathus minutus), a spittlebug (Lallemandana phalerata) [author's observations], and two capsid bugs (Aretas signatus and Aretas bifasciatus).

### Birds

Glochidion marianum is one of the many native plant species whose seeds are eaten by the Micronesian starling (Aplonis opaca).

## Conservation

In 1960, Raymond Fosberg described Glochidion marianum as being one of the more abundant trees in the ravine forests of southern Guam. In 1970, Benjamin Stone described it as being quite common, often as a volunteer in old fields.
As of 2024, the species has not been assessed by the IUCN.

## Uses

Edwin Safford wrote in 1905 that Glochidion marianum was used by the Chamorros of Guam to make cart shafts, as the wood is very strong.
Glochidion species are some of the most widespread medicinal plants used among the peoples of the Pacific, typically using the leaves and bark. However, no specific medicinal uses have been recorded from Guam.

## History and taxonomy

The French botanist, Charles Gaudichaud-Beaupré, extensively catalogued the flora of Guam during the 1819 expedition lead by Louis de Freycinet. However, Gaudichaud's 1826 botanical report does not mention the species. Nevertheless, a specimen in the herbarium of Swiss botanist Augustin Pyramus de Candolle was attributed to Gaudichaud. It was first described in the scientific literature as Glochidion marianum in 1863 in the journal Linnaea, by Johannes Müller Argoviensis, the conservator of the de Candolle herbarium.
Argoviensis again described the species in the journal Flora in 1865, but moved it to the genus Phyllanthus, and changed the species name to Phyllanthus gaudichaudi, honoring Gaudichaud-Beaupréso, who first collected the species, and so as not to confuse it with the related species, Phyllanthus marianus. However, William Edwin Safford retained the original species name, Glochidion marianum Muell. Arg., in his 1905 description.
A 2006 evaluation of the genus Glochidion recommended it be subsumed under the genus Phyllanthus. Subsequently, Wagner and Lorence in 2011 recommended a reorganization based on molecular phylogenetic studies and morphological characteristics. They proposed separating Glochidion marianum into two species, naming Guam's species Phyllanthus mariannensis and the Caroline Islands species Phyllanthus senyavinianus. However, as of 2024, Plants of the World Online does not consider Phyllanthus mariannensis to be a separate species, but rather a synonym of Glochidion marianum, which is endemic to both Guam and the Caroline Islands; likewise, Phyllanthus senyavinianus is listed as a synonym of Glochidion puberulum, which is endemic only to the Caroline Islands.

## Common name

Although Gaudichaud meticulously recorded the Chamorro names of many of Guam's plants, the first record of the Chamorro name for Glochidion marianum appears to have been 1905 by American botanist William Edwin Safford, who recorded the spellings "chosgô" and "chosgû." The same spelling was applied by S.F. Glassman in 1948. The first reference to the plant as "chosga" appears to be from E.D. Merrill in 1914.
However, in 1970, Stone recorded the Chamorro names chosga, chosgo, and åbas duendes. The latter name in Chamorro means "guava of the duendes," referring to the diminutive spirits of Chamorro folklore. Since guava were introduced to the Marianas from the New World, åbas duendes would necessarily be a Spanish-era name.
Marjorie Falanruw lists the name of Glochidion marianum on Pohnpei as luhwikitoh lol. The more general term for Glochidion species on Palau is ngolm, iodel, or kesengelengolm; on Chuuk is afor or amoses; and on Yap is ngumal or ngumol.