''Ischaemum nativitatis'', commonly known as the Christmas Island duck-beak, is a tropical grass in the family Poaceae. It is

endemic Endemism is the state of a species being found 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 found else ...

Christmas Island Christmas Island, officially the Territory of Christmas Island, is an Australian external territory comprising the island of the same name. It is located in the Indian Ocean, around south of Java and Sumatra and around north-west of the ...

, an Australian territory in the north-eastern Indian Ocean. The specific epithet comes from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''nativitas'' ("birth") referring to the birth of Christ, or Christmas, after the name of the island.''Ischaemum nativitatis''.
Flora of Australia Online.

Description

The Christmas Island duck-beak is an erect, tufted grass, 250–700 mm tall, with the stems often branched and the nodes smooth. The leaves are 30–110 mm long, 2.5–7 mm wide and are scattered along the stem. The two bristly racemes are 15–50 mm long, with long and hairy

pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures ...

s and

rachis In biology, a rachis (from the grc, ῥάχις [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this c ...

, and with paired,

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

spikelets 4.5 mm long and distinctly

awn AWN may stand for: * Awn Access to Justice Network in Gaza Strip, Legal Aid Network operate in Gaza Strip, Palestine * Animation World Network, an online organization for animators * Avant Window Navigator, a dock-like bar that tracks open windows ...

ed. The

glume In botany, a glume is a bract (leaf-like structure) below a spikelet in the inflorescence (flower cluster) of grasses (Poaceae) or the flowers of sedges (Cyperaceae). There are two other types of bracts in the spikelets of grasses: the lemma and ...

s are leathery at the base; the lower, bidentate glume has two membranous wings in the apical half; the upper glume has a winged keel towards the apex and a 6 mm awn. The

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s have glassy lemma and leathery palea about 3.5 mm long, with the awn of the upper lemma 15 mm long and twisted at the base.

Distribution and habitat

The grass occurs sporadically along the northern and western coasts of the island. Habitat types include exposed

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

pinnacles, pockets of

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and ...

sand, and near stands of ''

Scaevola taccada ''Scaevola taccada'', also known as beach cabbage, sea lettuce, or beach naupaka, is a flowering plant in the family Goodeniaceae found in coastal locations in the tropical areas of the Indo-Pacific. It is a common beach shrub throughout the Ar ...

'' and '' Pandanus nativitatis''.

Taxonomy

The grass was first recorded, though not properly described, by

Charles William Andrews Charles William Andrews (30 October 1866 – 25 May 1924) F.R.S., was a British palaeontologist whose career as a vertebrate paleontologist, both as a curator and in the field, was spent in the services of the British Museum, Department of Ge ...

and

Henry Nicholas Ridley Henry Nicholas Ridley CMG (1911), MA (Oxon), FRS, FLS, F.R.H.S. (10 December 1855 – 24 October 1956) was an English botanist, geologist and naturalist who lived much of his life in Singapore. He was instrumental in promoting rubber trees i ...

as ''I. foliosum'' var. ''leiophyllum'' Hack. ex Rendle, a

variety Variety may refer to: Arts and entertainment Entertainment formats * Variety (radio) * Variety show, in theater and television Films * ''Variety'' (1925 film), a German silent film directed by Ewald Andre Dupont * ''Variety'' (1935 film), ...

endemic to Christmas Island. Otto Stapf elevated it to species status, naming it ''I. nativitatis'', but did not publish it. In 1953, a full description was published, but without a

diagnosis, leaving the name still invalid under the

International Code of Botanical Nomenclature The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN) is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all those "trad ...

. In 1985, ''I. nativitatis'' became the valid name when a full Latin description was published. Full nomenclatural reference: *''Ischaemum nativitatis'' Jansen ex Renvoize, Kew Bull. 40: 447. 1985.Renvoize, Kew Bull. 40: 447. 1985. **''Ischaemum foliosum'' var. ''leiophyllum'' Hack. ex Rendle, in C.W.Andrews, Monograph Christmas Island 192. 1900. nvalid nomen nudum**''Ischaemum nativitatis'' Jansen, 1953. nvalid nomen nudum The grass is closely related to ''I. foliosum'' from New Caledonia and

Vanuatu Vanuatu ( or ; ), officially the Republic of Vanuatu (french: link=no, République de Vanuatu; bi, Ripablik blong Vanuatu), is an island country located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is east of no ...

References

nativitatis Endemic flora of Christmas Island Poales of Australia Plants described in 1985 {{Panicoideae-stub