Ischaemum nativitatis
Encyclopedia
Ischaemum nativitatis, commonly known as the Christmas Island Duck Beak, is a tropical grass
in the Poaceae
family
. It is endemic to Christmas Island
, an Australia
n territory in the north-eastern Indian Ocean
. The specific epithet comes from the Latin
nativitas (birth) referring to the birth of Christ, or Christmas, after the name of the island.
are 30–110 mm long, 2.5–7 mm wide and are scattered along the stem. The two bristly raceme
s are 15–50 mm long, with long and hairy pedicel
s and rachis
, and with paired, [Sessility (botany)|[sessile]] spikelets 4.5 mm long and distinctly awned. The glumes 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
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.
pinnacles behind the sea cliffs, in pockets of coral
line sand, and in front of dense stands of Scaevola taccada
and Pandanus nativitatis.
and Henry Nicholas Ridley
as I. foliosum var. leiophyllum Hack. ex Rendle, a variety endemic to Christmas Island. Otto Stapf
later determined that the Christmas Island specimens represented a distinct species, I. nativitatis Stapf, but again failed to publish the name validly. In 1953 P. Jansen tried to validate the name by publishing a full description, but omitted the required Latin
diagnosis, leaving the name still invalid under the International Code of Botanical Nomenclature. Eventually, in 1985, S. A. Renvoize validated the name I. nativitatis by publishing a full Latin description.
The grass is closely related to I. foliosum Hack. from New Caledonia
and Vanuatu
, which it resembles in appearance.
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 ...
in the Poaceae
Poaceae
The Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...
family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
. It is endemic to Christmas Island
Christmas Island
The Territory of Christmas Island is a territory of Australia in the Indian Ocean. It is located northwest of the Western Australian city of Perth, south of the Indonesian capital, Jakarta, and ENE of the Cocos Islands....
, an Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n territory in the north-eastern Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
. The specific epithet comes from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
nativitas (birth) referring to the birth of Christ, or Christmas, after the name of the island.
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 leavesLeaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are 30–110 mm long, 2.5–7 mm wide and are scattered along the stem. The two bristly raceme
Raceme
A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
s are 15–50 mm long, with long and hairy pedicel
Pedicel (botany)
A pedicel is a stem that attaches single flowers to the main stem of the inflorescence. It is the branches or stalks that hold each flower in an inflorescence that contains more than one flower....
s and rachis
Rachis
Rachis is a biological term for a main axis or "shaft".-In zoology:In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually form the supporting axis of the body and is then called the spine or vertebral column...
, and with paired, [Sessility (botany)|[sessile]] spikelets 4.5 mm long and distinctly awned. The glumes 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
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s have glassy lemma
Lemma (botany)
Lemma is a phytomorphological term used in botany referring to a part of the spikelet of grasses . It is the lowermost of two chaff-like bracts enclosing the grass floret. It often bears a long bristle called an awn, and may be similar in form to the glumes - chaffy bracts at the base of each...
and leathery palea
Palea (botany)
Palea, in botany, refers to one of the bract-like organs of the grass spikelet . It is the uppermost of the two chaff-like bracts that enclose the grass floret . It is often cleft at the tip, implying that it may be a double structure derived from the union of two separate organs...
about 3.5 mm long, with the awn of the upper lemma 15 mm long and twisted at the base.
Distribution and habitat
Found only on Christmas Island, the grass occurs sporadically along the northern and western coasts, on exposed limestoneLimestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
pinnacles behind the sea cliffs, in pockets of coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...
line sand, and in front of dense stands of Scaevola taccada
Scaevola taccada
Scaevola taccada, also known as Beach Cabbage, Sea Lettuce, Beach Naupaka, Naupaka kahakai , Merambong and Ngahu is a flowering plant in the family Goodeniaceae found in open coastal locations of the tropical areas of the Indo-Pacific...
and Pandanus nativitatis.
Taxonomic history
The grass was first recorded, though not properly described, by Charles William AndrewsCharles William Andrews
Charles William Andrews 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 Geology.-Biography:...
and Henry Nicholas Ridley
Henry Nicholas Ridley
Henry Nicholas Ridley CMG , MA , FRS, FLS, F.R.H.S. was an English botanist and geologist.Born at West Harling Hall, Norfolk, England...
as I. foliosum var. leiophyllum Hack. ex Rendle, a variety endemic to Christmas Island. Otto Stapf
Otto Stapf
Otto Stapf FRS was an Austrian born botanist and taxonomist.Stapf trained in Vienna, moving to Royal Botanic Gardens, Kew in 1890. He was keeper of the Herbarium from 1909 to 1920...
later determined that the Christmas Island specimens represented a distinct species, I. nativitatis Stapf, but again failed to publish the name validly. In 1953 P. Jansen tried to validate the name by publishing a full description, but omitted the required Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
diagnosis, leaving the name still invalid under the International Code of Botanical Nomenclature. Eventually, in 1985, S. A. Renvoize validated the name I. nativitatis by publishing a full Latin description.
The grass is closely related to I. foliosum Hack. from New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...
and Vanuatu
Vanuatu
Vanuatu , officially the Republic of Vanuatu , is an island nation located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is some east of northern Australia, northeast of New Caledonia, west of Fiji, and southeast of the Solomon Islands, near New Guinea.Vanuatu was...
, which it resembles in appearance.