''Pandanus christmatensis'' is a

dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...

tropical plant in the screwpine genus. 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 elsew ...

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

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

n territory in the north-eastern

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...

. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

, ''"christmatensis"'', comes from its native locality.Flora of Australia Online.

Description

''Pandanus christmatensis'' is a small tree or shrub, with prop roots, that grows to 10 m in height. Its

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

are 1–2 m long and 50–80 mm wide, dark green and with marginal prickles. The

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. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

has white

bract In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...

s. The fruit is orange when ripe.

Distribution and habitat

The plant forms dense, tangled thickets on the shore terraces of the island, often next to the sea, on 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 ...

cliffs with little soil. It also occurs inland beneath the

rainforest Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...

canopy Canopy may refer to: Plants * Canopy (biology), aboveground portion of plant community or crop (including forests) * Canopy (grape), aboveground portion of grapes Religion and ceremonies * Baldachin or canopy of state, typically placed over an a ...

, particularly on limestone

scree Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits. Talus deposits typically ha ...

Taxonomy

The plant is closely related to ''

Pandanus tectorius ''Pandanus tectorius'' is a species of ''Pandanus'' (screwpine) that is native to Malesia, Papuasia, eastern Australia, and the Pacific Islands. It grows in the coastal lowlands typically near the edge of the ocean. Common names in English inclu ...

'', which is widely distributed through the region, and is very similar to ''Pandanus platycarpus'' from

Zanzibar Zanzibar (; ; ) is an insular semi-autonomous province which united with Tanganyika in 1964 to form the United Republic of Tanzania. It is an archipelago in the Indian Ocean, off the coast of the mainland, and consists of many small islands ...

References

Notes

Sources

* * christmatensis Endemic flora of Christmas Island Plants described in 1905 Taxa named by Ugolino Martelli {{Pandanales-stub