Cycas cairnsiana is a species of cycad

Cycad

Cycads are seed plants typically characterized by a stout and woody trunk with a crown of large, hard and stiff, evergreen leaves. They usually have pinnate leaves. The individual plants are either all male or all female . Cycads vary in size from having a trunk that is only a few centimeters...

 in the genus Cycas

Cycas

Cycas is the type genus and the only genus currently recognised in the cycad family Cycadaceae. About 95 species are currently accepted. The best-known species is Cycas revoluta, widely cultivated under the name "Sago Palm" or "King Sago Palm" due to its palm-like appearance although it is not a...

, native to northern 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...

 in northern Queensland

Queensland

Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...

 on the Newcastle Range.

The stems grow to 2-5 m tall and 12-16 cm diameter, with swollen base. The leaves

Leaf

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 dark orange-brown tomentose on emerging, then glaucous blue-green and glabrous with age, 60-110 cm long, bowed, keeled, pinnate, with 180-220 leaflets, the leaflets 8-18 cm long and 2-4 mm wide. The petiole

Petiole (botany)

In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...

s are 18-27 cm long, and armed with sharp spines.

The female cones

Strobilus

A strobilus is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but many botanists restrict the use of the term cone to the woody seed strobili of conifers...

 are open, with sporophyll

Sporophyll

A sporophyll is a leaf that bears sporangia. Both microphylls and megaphylls can be sporophylls. In heterosporous plants, sporophylls bear either megasporangia , or microsporangia...

s 16-21 cm long, with two to four ovules per sporophyll. The lamina is narrowly triangular, with toothed margins and an apical spine. The sarcotesta

Sarcotesta

The sarcotesta is the outermost fleshy covering of Cycad seeds. Below this layer is usually the sclerotesta, the coating that makes direct contact with the cycad seed. In some species, however, there is an intermediate layer that is thought to be used in water retention and storage....

 is yellow-brown with a waxy coating, the sclerotesta

Sclerotesta

Sclerotesta is the innermost fleshy coating of cycad seeds, usually located directly below the Sarcotesta....

 ovoid and flattened. The male cones are solitary, ovoid, 16-20 cm long and 7-10 cm diameter, brown, and with an upturned apical spine.

It is named after William Cairns

William Cairns

Sir William Wellington Cairns, KCMG was a British colonial administrator, born in County Down, Ireland. He served in various senior colonial civil service posts in the British Empire before being appointed Governor of Queensland in January 1875. He held the post for two years before becoming...

, governor of Queensland from 1875–1877.

Habitat

It grows in dry, rocky, and open woodland terrain on soils derived from granite. Its range is limited to the Newcastle Range of northeast Queensland, with seasonal rainfall of about 1350 mm. This cycad is a close relative of both Cycas couttsiana and Cycas platyphylla. The plants are remarkable for their intense blue colour, and their resilience to the seasonal extremes of their native range. Its conservation status is near-threatened.