Zanthoxylum brachyacanthum

Zanthoxylum brachyacanthum, known as thorny yellowwood, satinwood, satinwood or scrub mulga,[2] is a species of flowering plant in the family Rutaceae and is endemic to north-eastern Australia. It is a rainforest shrub or tree with thick, cone-shaped spines on the trunk and prickles on the branches, pinnate leaves, and male and female flowers arranged in panicles.

Thorny yellow-wood
Trunk at Tooloom National Park
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Sapindales
Family:	Rutaceae
Genus:	Zanthoxylum
Species:	Z. brachyacanthum
Binomial name
Zanthoxylum brachyacanthum F.Muell.[1]
Synonyms[1]
Fagara brachyacantha (F.Muell.) Engl. Fagara brachyacanthum Engl. orth. var. Fagara venefica (F.M.Bailey) Engl. Fagara venenifica Engl. orth. var. Xanthoxylon brachyacanthum F.Muell. orth. var. Xanthoxylum brachyacanthum F.Muell. orth. var. Zanthoxylum veneficum F.M.Bailey

Description

Zanthoxylum brachyacanthum is a shrub or tree that typically grows to a height of 25 m (82 ft) usually with prickles on the branches and thick, cone-shaped spines on the trunk and older branches. The leaves are pinnate, arranged alternately, with seven to thirteen leaflets, and 120–300 mm (4.7–11.8 in) long. The leaflets are egg-shaped to elliptic, 40–150 mm (1.6–5.9 in) long and 15–55 mm (0.59–2.17 in) wide, the side leaflets on a petiolule 30–90 mm (1.2–3.5 in) long and the end leaflet on a petiolule 30–180 mm (1.2–7.1 in) long.[2][3][4][5]

The flowers are arranged in panicles on the ends of branches, or in leaf axils or both and 15–25 mm (0.59–0.98 in) long. The flowers are sessile or on pedicels up to 2.5 mm (0.098 in) long, the four sepals joined at the base and about 1 mm (0.039 in) long, the four petals greenish cream-coloured and 4–5 mm (0.16–0.20 in) long. Male flower have four stamens 3.5–8 mm (0.14–0.31 in) long with anthers about 3 mm (0.12 in) long. Females flowers have a single carpel about 3 mm (0.12 in) long with a short style, sometimes with rudimentary stamens. Flowering occurs from September to November and the fruit is a shiny bright red, later wrinkled dark brown, spherical or oval follicle 7–8 mm (0.28–0.31 in) long containing a single black seed.[2][3][4][5]

Taxonomy

Zanthoxylum brachyacanthum was first formally described in 1857 by Ferdinand von Mueller in Transactions of the Philosophical Institute of Victoria from specimens collected in "the Araucaria forests of Moreton Bay".[6][7]

Zanthoxylum veneficum, listed as a synonym of Z. brachyacanthum by the Australian Plant Census, is recognised as a different species in Queensland.[1][8][9]

Distribution and habitat

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.[4] 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.[4]

Ecology

The leaves of Zanthoxylum brachyacanthum serve as a food plant for butterfly larvae including those of the orchard swallowtail butterfly[10] and the fuscus swallowtail.[4][11]

Uses

This tree's small size, the interesting trunk, the attractive flowers and foliage makes the thorny yellowwood a candidate ornamental plant. The timber is deep yellow and close grained, and thus it might be suitable for decorative work.[4]

The plant family contains some interesting alkaloids, coumarins, furano coumarins, and pryanocoumarins, ancetophenones such as Zantholoxylin, flavanoids like amurensin, and polyhydroxol flavainoids, and Amides.[12]

The essential (leaf) oil of Z. brachyacanthum was rich in α-pinene (46%), β-caryophyllene (14%) and bicyclogermacrene (12.5%).[13]

• 
  Female flowers
• 
  Male flowers
• 
  Fruit

References

1. "Zanthoxylum brachyacanthum". Australian Plant Census. Retrieved 17 August 2020.
2. Hartley, Thomas G.; Wilson, Annette J.G. (ed.) (2013). Flora of Australia (Volume 26). Canberra: Australian Biological Resources Study. p. 76. Retrieved 17 August 2020.CS1 maint: extra text: authors list (link)
3. Richards, P.G. (2009). "Zanthoxylum brachyacanthum F.Muell". PlantNET. Royal Botanic Gardens & Domain Trust, Sydney Australia. Retrieved 2009-06-06.
4. Floyd, Alexander G. Rainforest Trees of Mainland South-eastern Australia. Inkata Press 1989. p. 345. ISBN 0-909605-57-2.
5. "Zanthoxylum brachyacanthum". Australian Tropical Rainforest Plants. Retrieved 17 August 2020.
6. "Philotheca virgata". APNI. Retrieved 17 August 2020.
7. von Mueller, Ferdinand (1857). "Account of some new Australian plants". Transactions of the Philosophical Institute of Victoria. 2: 65. Retrieved 17 August 2020.
8. "Species profile—Zanthoxylum veneficum". Queensland Government Department of Environment and Science. Retrieved 17 August 2020.
9. "Species profile—Zanthoxylum brachyacanthum". Queensland Government Department of Environment and Science. Retrieved 17 August 2020.
10. "Food plants for Australian butterflies and caterpillars". Australian Butterfly Sanctuary. Retrieved 2009-06-04.
11. Herbison-Evans, Don; Samson, Peter R.; Crossley, Stella (31 March 2009). "Papilio fuscus Goeze, 1779: Fuscus Swallowtail". Don Herbison-Evans, University of Technology Sydney. Archived from the original on May 28, 2009. Retrieved 2009-06-04.
12. Fish, F.; Waterman, P. G. (1973). "Chemosystematics in the Rutaceae II. The Chemosystematics of the Zanthoxylum/Fagara Complex". International Association for Plant Taxonomy (IAPT).
13. Brophy, J. J.; Goldsack, R. J.; Forster, P. I.; Hutton, I. (2000). "Composition of the leaf oils of the Australian and Lord Howe Island species of Zanthoxylum (Rutaceae)". Journal of Essential Oil Research. 12 (3): 285–291. doi:10.1080/10412905.2000.9699517.

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