Xanthorrhoea

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Xanthorrhoea

Scientific classification

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Liliopsida
Order:	Asparagales
Family:	Xanthorrhoeaceae Dumort.
Genus:	Xanthorrhoea Sol. ex Sm.

Species

see text

Xanthorrhoea is a genus of flowering plants native to Australia and a member of family Xanthorrhoeaceae. The Xanthorrhoeaceae are monocots, part of order Asparagales. There are 28 species and five subspecies of Xanthorrhoea.^[1] All are perennials and have a secondary thickening meristem in the stem. Many, but not all, species develop an above ground stem. This is rough-surfaced, built from accumulated leaf-bases around the secondarily thickened trunk. The trunk is sometimes unbranched, some species will branch if the growing point is damaged and others naturally grow numerous branches. Flowers are borne on a long spike above a bare section called a scape, the total length can be up to four metres long in some species. Flowering occurs in a distinct flowering period, which varies for each species. Flowering can be stimulated by bushfire, in which case it occurs in the next flowering period after the fire.

It is commonly believed that the Xanthorrhoea grow at a rate of about an inch (2½ cm) per century. Xanthorrhoea do grow very slowly, but this is a gross underestimate: after an initial establishment phase the average rate of growth varies for each species but can be as high as about 2½ cm per year. Thus a five-metre tall member of one of the fastest growing Xanthorrhoea would be about 200 years old.

Xanthorrhoea may be cultivated, as seed is easily collected and germinated. Whilst they do grow slowly, quite attractive plants with short trunks (10 cm) and leaf crowns up to 1.5 m (to the top of the leaves) can be achieved in 10 years. The slow growth rate means that it can take 30 years to achieve a specimen with a significant trunk. Most Xanthorrhoea sold in nurseries are established plants taken from bushland. Nurseries charge high prices for the plants. However, there is a very low survival rate for nursery purchased plants, which may take 3-4 years to die. The most successful examples of transplanting have been where a substantial amount of soil (> 1 cubic metre) has been taken with the plants.

The best known common name for the Xanthorrhoea is blackboy. This name refers to the purported similarity in appearance of the trunked species to an Aboriginal boy holding an upright spear. Some consider this name to be politically incorrect, preferring grasstree, or in the South West the Noongar name balga for X. preissei. In South Australia it is commonly known as yakka, also spelled yacca and yacka. This probably is from a South Australian Aboriginal language,^[2] mostly likely Kaurna.

1 Traditional Aboriginal uses
2 Species
3 Image gallery
4 See also
5 References
6 External links

[edit] Traditional Aboriginal uses

Xanthorrhoea was important to the Aboriginal people who lived where it grew. The flowering spike made the perfect fishing spear. It was also soaked in water and the nectar from the flowers would give a sweet tasting drink. In the bush the flowers were used as a compass. This is because flowers on the warmer, sunnier side of the spike (usually the north facing side) often open before the flowers on the cooler side facing away from the sun.^[3]

The resin from Xanthorrhoea plants was used in spear-making^[4] and was an invaluable adherent for Aboriginal people.

[edit] Species

Xanthorrhoea acanthostachya
Xanthorrhoea acaulis
Xanthorrhoea arborea
Xanthorrhoea arenaria
Xanthorrhoea australis
Xanthorrhoea bracteata
Xanthorrhoea brevistyla
Xanthorrhoea brunonis
Xanthorrhoea caespitosa
Xanthorrhoea concava
Xanthorrhoea drummondii
Xanthorrhoea fulva
Xanthorrhoea glauca
Xanthorrhoea gracilis
Xanthorrhoea johnsonii
Xanthorrhoea latifolia
Xanthorrhoea macronema
Xanthorrhoea malacophylla
Xanthorrhoea media
Xanthorrhoea minor
Xanthorrhoea nana
Xanthorrhoea platyphylla
Xanthorrhoea preissii
Xanthorrhoea pumilio
Xanthorrhoea reflexa
Xanthorrhoea resinifera (also called Xanthorrhoea hastilis)
Xanthorrhoea semiplana
Xanthorrhoea thorntonii

[edit] Image gallery

Flower spikes on "blackboy" trees	The top of a Xanthorrhoea	A large group of Xanthorrhoea	A group of flowering Xanthorrhoea
Early stages of a flowering Xanthorrhoea stem	Flowering Xanthorrhoea	Old flower stem after seeds have been ejected

[edit] See also

Kingia and Dasypogon are unrelated Australian plants with a similar growth habit to Xanthorrhoea. Both genera have at times been confused with xanthorrhoeas and mis-named as grasstrees. Some plant classification systems such as Cronquist^[5] have included a wide range of other genera in the same family as Xanthorrhoea. However, later anatomical and phylogenetic research has supported the view of Dahlgren^[6] who regarded Xanthorrhoea as the sole member of the family Xanthorrhoeaceae.

[edit] References

^ Bedford, D.J. (1986) "Xanthorrhoea", in: A.S. George, (Ed) Flora of Australia 46:148-169
^ Peters, Pam, The Cambridge Australian English Style Guide, Cambridge University Press, 1996, p823
^ http://www.abc.net.au/gardening/stories/s1145455.htm
^ http://www.abc.net.au/quantum/s188496.htm
^ Cronquist, A.J. An Integrated System of Classification of Flowering Plants, Columbia University Press, New York 1981
^ Dahlgren, R.M.T., (1980), "A revised system of classification of the angiosperms" Bot.J. Linn. Soc. 80:91-124