Alloxylon pinnatum
Dorrigo waratah
Dorrigo waratah
Wikipedia links: Angiosperms > Eudicots > Proteales > Proteaceae > Aloxylon pinnatum
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Common name: Dorrigo waratah
Aside from Dorrigo waratah, it has also been called the Dorrigo oak, red silky oak, tree waratah, pink silky oak, red oak, Queensland waratah, and waratah oak
Conservation status: Rare or Threatened
The Dorrigo waratah is classified as 3RCa under the Rare or Threatened Australian Plant (ROTAP) criteria for threatened species, and listed as near threatened under the Queensland Nature Conservation Act 1992
The flowers are visited by the rare Richmond birdwing butterfly (Ornithoptera richmondia), which occurs in the same region
In 2016, the Dorrigo waratah was one of eleven species selected for the Save a Species Walk campaign in April 2016; scientists walked 300 km (190 mi) to raise money for collection of seeds to be prepared and stored at the Australian PlantBank at the Australian Botanic Garden, Mount Annan.
Protected areas it grows in, in NSW include Bellinger River National Park and Dorrigo National Park
Etymology:
The genus name is derived from Ancient Greek allo-, meaning "other" or "strange", and xylon, meaning "wood"
It refers to the genus's unusual cell architecture compared with the related genera Telopea and Oreocallis
The species name refers to the pinnate leaves
Flowers:
The prominent pinkish-red flower heads, known as inflorescences, appear in spring and summer; these are made up of 50 to 140 individual flowers arranged in corymb or raceme
The pinkish-red compound flowerheads, known as inflorescences, are up to 20 cm across in spring to summer, and contain between 50 and 140 smaller flowers, arranged in a corymb or raceme
These individual flowers are 3–3.8 cm long and sit atop stalks (known as pedicels) up to 3.5 cm in length, which arise in pairs off the main stalk within the inflorescence
Each flower consists of a tubular perianth, which partly splits along one side at anthesis to release the thick style
The stigma is contained within a slanting disc-like structure at the tip of the style
The tubular perianth splits into four segments at its tip, and the anther lies in the concave parts within each of these segments
The flower parts are smooth and hairless
The pollen is crimson
Fruit:
Rectangular woody seed pods, which bear two rows of winged seeds
After flowering, the 8–10 cm long woody seedpod develops
Cylindrical in shape, it splits down one side to release the seeds, which are ripe from February to June
They are arranged in two rows, with at least four seeds in each row. Each seed is separated from the others by a membranous separator, and has a long rectangular wing, which is much longer than the seed itself
Leaves:
It has shiny green leaves that are either pinnate (lobed) and up to 30 cm long
Or lanceolate (spear-shaped) and up to 15 cm long
The green foliage consists of several distinct juvenile and adult leaf forms, which are arranged alternately along the stems
Juvenile leaves are light green and at first simple, with a single blade
Successive leaves on more mature plants become more complex, or pinnate, with deep lobes; these leaves are up to 30 cm long with 2–11 leaflets
Some adult leaves are simple—with a single lanceolate leaf blade—and up to 15 cm long; these are generally located near the flower heads
Among the green foliage there are occasional yellow leaves. New branchlets and leaves are covered in brown hair
Stem & branches:
Reaches 25 m high\
Non-buttressed trunk of 1.5 m diameter at breast height (dbh)
The bark is greyish brown and covered in many small pimples, rendering it sandpaper-like in texture
Roots:
Habit:
Habitat:
It is found in warm-temperate rainforest from altitudes of 700 to 1,250 m along the McPherson Range in south-east Queensland and the Dorrigo Plateau in northern New South Wales, with dominant tree species such as coachwood (Ceratopetalum apetalum) and Antarctic beech (Lophozonia moorei)
In Queensland it is associated with golden sassafras (Doryphora sassafras) and native crabapple (Schizomeria ovata)
It commonly grows on southern aspects of hills and slopes
Distribution:
South-east Queensland and northern NSW
Additional notes:
Taxonomy
Known for many years as Oreocallis pinnata, it was transferred to the new genus Alloxylon by Peter Weston and Mike Crisp in 1991
This genus contains the four species previously classified in Oreocallis that are found in Australasia
Its terminal globular flowers indicate that the species is pollinated by birds
First described as a variety of what was then known as Embothrium wickhamii by Joseph Maiden and Ernst Betche in 1911 after a collection by J.L.Boorman, the Dorrigo waratah was raised to species status and reclassified as Oreocallis pinnata by Dutch botanist Hermann Otto Sleumer in 1954
The Australian members of the genus Oreocallis were recognised as markedly distinct from the South American species, which saw them allocated to the new genus Alloxylon
Hence, Oreocallis pinnata was given the new combination Alloxylon pinnatum in 1991 by Peter Weston and Mike Crisp of the Royal Botanic Gardens in Sydney
A. pinnatum and the other three tree waratah species lie in the subtribe Embothriinae, along with the true waratahs (Telopea)
Oreocallis and the Chilean firetree (Embothrium coccineum) from South America
Almost all these species have red flowers that are terminal (arising at the ends of branches), and hence the subtribe's origin and floral appearance most likely predates the splitting of the supercontinent Gondwana into Australia, Antarctica, and South America over 60 million years ago
The position, colour and tubular shape of the flowers suggest that they are bird-pollinated and have been so since the radiation of nectar-feeding birds such as honeyeaters in the Eocene
Identification
The Dorrigo waratah can be distinguished from other members of the genus Alloxylon by its pinnate adult leaves
This feature serves to differentiate it as other species in the genus have simple adult leaves
The other species have inflorescences with fewer flowers (50 maximum), and have yellow pollen
Fossils
Triporopollenites ambiguus is an ancient member of the proteaceae known only from pollen deposits, originally described from Eocene deposits in Victoria
The fossil pollen closely resembles that of the Tasmanian waratah (Telopea truncata), A. pinnatum and Oreocallis grandiflora
Cladistic analysis of morphological features within the Embothriinae showed A. pinnatum to be the earliest offshoot within the genus and sister to the other three species
Along with members of other genera in the Embothriinae, A. pinnatum has crimson pollen, while the other three Alloxylon species have yellow pollen
Hence the ancestral pollen colour was likely red, and remained so with the emergence of the genus Alloxylon, yet changed to yellow after the divergence of A. pinnatum
Cultivation
The bright, prominently displayed flowers and bird-attracting properties of the Dorrigo waratah make it a desirable garden plant
It reaches only about 6–10 m in cultivation, but has proven difficult to grow
It has been successfully cultivated at the Australian National Botanic Gardens in Canberra in a sheltered position in part-shade with a thick layer of mulch
It is propagated most easily by seed, which is ripe from February to June and keeps for around twelve months
Seedlings often perish when they reach 15 cm high, and are difficult to transplant
It has also been grown at Mount Tomah Botanic Garden, where it was noted to be exacting in its requirements, needing very good drainage as well as a sheltered location to survive
It is slow growing; specimens planted in 1989 have been flowering since 1999
The considerably easier to grow Queensland tree waratah (A. flammeum) has been considered as a stock plant for grafting
The pinkish red timber has been used for making cabinets and furniture
It is soft and light, weighing 500 kg per cubic metre
The cut flowers have a long vase life
Sources of information:
(2023)