Allocasuarina humilis
Encyclopedia
Allocasuarina humilis, commonly known as the dwarf sheoak or dwarf casuarina, is a woody shrub
of the family Casuarinaceae
endemic to the south-west
of Western Australia
.
. The reddish-brown male flower spikes are between 6 and 18 mm long and the warty cones are cylindrical, about 12 to 22 mm in length and 10 to 17 mm in diameter.
in 1841 from a specimen cultivated in Berlin Botanical Gardens, the dwarf sheoak was transferred to the new genus Allocasuarina
by botanist Lawrie Johnson
in 1982. The species name is the Latin
adjective hǔmǐlǐs "on - " or "close to the ground" (hǔmus). A 2003 molecular study of the family Casuarinaceae showed the dwarf sheoak and the horned sheoak (A. thuyoides) to be sister taxa, and form a clade with A. thuyoides, A. microstachya, karri oak (A. decussata) and western sheoak (A. fraseriana
), all from Western Australia.
in the north, to the south coast, where it extends eastwards to Israelite Bay. It grows on sand, sand over laterite
, gravel, or clay.
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
of the family Casuarinaceae
Casuarinaceae
Casuarinaceae is a family of dicotyledonous flowering plants placed in the order Fagales, consisting of 3 or 4 genera and approximately 70 species of trees and shrubs native to the Old World tropics , Australia, and the Pacific Islands...
endemic to the south-west
Southwest Australia
Southwest Australia is a biodiversity hotspot that includes the Mediterranean forests, woodlands, and scrub ecoregions of Western Australia. The region has a wet-winter, dry-summer Mediterranean climate, one of five such regions in the world...
of Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
.
Description
Unlike many sheoaks which grow into trees, Allocasuarina humilis only reaches 20 cm to 2 m (8-80 in) in height. A many branched shrub, its branchlets ascend from larger branches and reach 12 cm (5 in) in length. As with other sheoaks, its foliage consists of slender green branchlets informally referred to as "needles" but more correctly termed cladodes. The cladodes are segmented, and the true leaves are tiny teeth encircling each joint. It can be dioecius or moneciousPlant sexuality
Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....
. The reddish-brown male flower spikes are between 6 and 18 mm long and the warty cones are cylindrical, about 12 to 22 mm in length and 10 to 17 mm in diameter.
Taxonomy
Originally described as Casuarina humilis by German naturalists Christoph Friedrich Otto and Albert Gottfried DietrichAlbert Gottfried Dietrich
Albert Gottfried Dietrich was a German botanist who was a native of Danzig.Dietrich was curator at the Botanical Garden in Berlin and was an instructor at the institute of horticulture at Berlin-Schöneberg...
in 1841 from a specimen cultivated in Berlin Botanical Gardens, the dwarf sheoak was transferred to the new genus Allocasuarina
Allocasuarina
Allocasuarina is a genus of trees in the flowering plant family Casuarinaceae. They are endemic to Australia, occurring primarily in the south. Like the closely related genus Casuarina, they are commonly called sheoaks or she-oaks, they are notable for their long, segmented branchlets that...
by botanist Lawrie Johnson
Lawrence Alexander Sidney Johnson
Lawrence Alexander Sidney Johnson, known as Lawrie Johnson, was an Australian taxonomic botanist. He worked at the Royal Botanic Gardens, Sydney, for the whole of his professional career, as a botanist , Director and Honorary Research Associate .Alone or in collaboration with colleagues, he...
in 1982. The species name is 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...
adjective hǔmǐlǐs "on - " or "close to the ground" (hǔmus). A 2003 molecular study of the family Casuarinaceae showed the dwarf sheoak and the horned sheoak (A. thuyoides) to be sister taxa, and form a clade with A. thuyoides, A. microstachya, karri oak (A. decussata) and western sheoak (A. fraseriana
Allocasuarina fraseriana
Allocasuarina fraseriana, commonly known as western sheoak, common sheoak or just sheoak, is a tree in the family Casuarinaceae. Endemic to Western Australia, it occurs near the coast in the south west corner of the State, from Jurien to Albany .In ideal conditions, Western Sheoak grows to a...
), all from Western Australia.
Distribution and habitat
Allocasuarina humilis is found across southwest Western Australia, from the Murchison RiverMurchison River (Western Australia)
The Murchison River is the second longest river in Western Australia. It flows for about from the southern edge of the Robinson Ranges to the Indian Ocean at Kalbarri. It has a mean annual flow of about 200 million cubic metres.-Course:...
in the north, to the south coast, where it extends eastwards to Israelite Bay. It grows on sand, sand over laterite
Laterite
Laterites are soil types rich in iron and aluminium, formed in hot and wet tropical areas. Nearly all laterites are rusty-red because of iron oxides. They develop by intensive and long-lasting weathering of the underlying parent rock...
, gravel, or clay.