Zanthoxylum brachyacanthum

Zanthoxylum brachyacanthum
File:Zanthoxylum brachyacanthum Tooloom NP April 1998.jpg
Thorny Yellowwood at Tooloom National Park, Australia
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Sapindales
Family:	Rutaceae
Genus:	Zanthoxylum
Species:	Z. brachyacanthum
Binomial name
Zanthoxylum brachyacanthum F. Muell.
Synonyms
Fagara brachyacantha Engl.

Zanthoxylum brachyacanthum, known as the Thorny Yellowwood or Satinwood, is an Australian rainforest tree. The natural range is from the Clarence River (29° S) in New South Wales to tropical Queensland in the Eungella National Park and the Wet Tropics region.

This tree is in the family Rutaceae, which is sometimes known as the "citrus family" because this family also contains all of the species (such as the orange, lemon, etc.) in the genus Citrus.

This tree grows on a variety of subtropical, tropical and drier rainforests, often on volcanic soils. Young trees are easily identified in the rainforest by the thorny trunk and the dark green glossy leaves.

The leaves of Zanthoxylum brachyacanthum serve as a food plant for butterfly larvae including those of the Orchard Swallowtail Butterfly and the Fuscus Swallowtail.

Description

This is a small tree, up to 15 metres tall and 35 cm around the trunk. The bark is grey, wrinkled and features sharp pointed lenticels on young trees. Older trees appear more smooth barked. Trees are mostly not buttressed or flanged at the base.

The leaves are alternate and pinnate, with five to sixteen shiny leaflets. Leaflets are alternate, 4 to 9 cm long, egg shaped or oblong, usually toothed and with evident oil glands. The branchlets have prickles and are green or blue/green. The leaf scars are noticeable.

The flowers appear on panicles from October to November. They are pink or red, with a yellowish centre. The flowers are very attractive to insects because of their nectar.

The fruit matures from February to May, being a single cocci, bright red and shiny. It later changes color to a wrinkled dark brown, each fruit being 10 mm long. The cocci splits into two valves, with one black seed each, and are 6 mm long and shiny, attached by a membrane of a similar length. The seed germination is erratic.

Uses

This tree's small size, the interesting trunk, the attractive flowers and foliage makes the Thorny Yellowwood suitable as an ornamental plant. The timber is deep yellow and close grained, and thus it is suitable for decorative work.

The plant family contains some interesting alkaloids, coumarins, furano coumarins, and pryanocoumarins, ancetophenones such as Zantholoxylin, flavanoids like amurensin, and polyhydroxol flavainoids, and Amides.

The essential (leaf) oil of Z. brachyacanthum was rich in α-pinene (46%), β-caryophyllene (14%) and bicyclogermacrene (12.5%).

Notes

References

• Floyd, A.G., Rainforest Trees of Mainland South-eastern Australia, Inkata Press 1989, ISBN 0-909605-57-2

External links

• Zanthoxylum brachyacanthum at PlantNET, NSW Flora online.
• Zanthoxylum brachyacanthum at the Australian National University's Australian Pollen and Spore Atlas.