Glochidion marianum

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.^[3]

• 
  Minuscule flowers. Dededo, Guam
• 
  Seeds inside mature fruit. Dededo, Guam.
• 
  Unripe fruit. Dededo, Guam
• 
  Stem and leaves. Dededo, Guam

Glochidion marianum grows both in the volcanic soils of southern Guam, as well as the limestone that is typical of northern Guam.^[4] 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.^[5]

Most Glochidion species are known to have a mutualistic relationship with moths of the genus Epicephala.^[6][7][8][9] 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)^[10]
• a true weevil (Swezeyella muscosa)^[11]
• a jewel beetle (Chrysodema ventralis)^[12]
• a leafhopper (Tartessus ochraceus)^[13]

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),^[14] a leafhopper (Tartessus swezeyi),^[13] a chalcid wasp (Cirrospiloideus guamensis),^[15] a true weevil (Trigonops inaequalis)^[11], a jewel bug (Calliphara munda),,^[16] a sap beetle (Haptognathus minutus),^[17] a spittlebug (Lallemandana phalerata)^[18][19] [author's observations], and two capsid bugs (Aretas signatus and Aretas bifasciatus).^[20]

Glochidion marianum is one of the many native plant species whose seeds are eaten by the Micronesian starling (Aplonis opaca).^[21]

In 1960, Raymond Fosberg described Glochidion marianum as being one of the more abundant trees in the ravine forests of southern Guam.^[22] In 1970, Benjamin Stone described it as being quite common, often as a volunteer in old fields.^[3]

As of 2024^[update], the species has not been assessed by the IUCN.

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.^[23]

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.^[24]