Xanthorrhoea

Xanthorrhoea malacophylla

The grass trees ( Xanthorrhoea ) are the only genus in the subfamily Xanthorrhoeoideae in the family of grass tree plants ( Xanthorrhoeaceae sl) within the order of asparagus -like ( Asparagales ). The family is found only in Australia, they are typical elements of the Australis. The botanical genus name is derived from the Greek xanthorrhoea xanthos for yellow and Rhoe for flow and refers to the resin. English common names for this genus are also Yacca, Blackboy, or Grasstree. There are about 28 species.

• 6.1 Notes and references

Description

Habit and foliage leaves

Xanthorrhoea species are evergreen xerophytic perennial plants. The plants include yellow, red or brown resin. Many species form a woody, sometimes slightly branched root over many years. For the other species, the stem axis is largely underground and can be designed as rhizome or tuber. It is anomalous secondary growth present, this is done by a single Kambiumring. Grass trees reach a height of 2 to a maximum of 6 meters and up to age 350 to 450 years ( A radiocarbon age determination gave an age of 600 years ). The height increment per year is only 0.8 to 6 cm (specification determined by only a few detailed studies of AC Borsboom 2005). The plant parts are mostly hairless.

The alternate and spiral, basal or terminally arranged on the stem in rosette leaves are simple and sessile. The leaf blade is narrow and linear, unifazial, grassy, ​​short to very long depending on the type, leathery, parallel-veined. The smooth leaf margin has microscopic trichomes. The leaves remain about 2 to 3 years green. Often parts remain dead leaves on the trunk and get protection against evaporation and fires.

Inflorescences and flowers

Most Xanthorrhoea species make their first inflorescence aged at least 5-6 years. Each type has a fixed period of prosperity. Terminally on mostly long Blütenstandsschäften stand together many flowers in total composite inflorescences of aged men part inflorescences. There are support and cover sheets available.

The small, hermaphroditic flowers are radial symmetry and threefold. There are two circles, each with three free bracts present; they are different in the two circles that the outer circle are stiffer and shorter. There are two circles, each with three free, fertile stamens present; they are not intertwine with the bloom cladding. The sulcaten pollen grains have a Aperturat. The three carpels are fused to an upper constant ( syncarp ) ovary. Each of the three chambers fruit has three to eight ovules. The style ends in a point, head-shaped or three-lobed stigma. The Septalnektarien produce much nectar.

Fruit and seeds

There shall be woody or cartilaginous, lokulizidale capsule fruits that contain three to six seeds. The black seeds by Phytomelane have oily endosperm. The fruit stand some form Xanthorrhoea species about 10,000 seeds. The seeds remain viable for about five years.

Ingredients and chromosome number

It can be stored calcium oxalate crystals. Of ingredients are important: cyanidin, flavonols, kaempferol, quercetin and proanthocyanidins in some species. The chromosome number is 2n = 22 uniformly

Ecology

Grass trees are often the undergrowth in Australian Eucalyptuswäldern. By some properties they survive the frequent bush fires in the Australian drylands almost intact: Parts of dead leaves protect the tribe. The Spitzenmeristem survives fire because it is sunk.

The fires are even necessary for the growth of grass trees, because competing species are thereby burned to mineral nutrient. Many grass trees are among the Pyrophyten, their dissemination and reproduction is encouraged by fire. Its trunk is usually by the soot of the fires colored black (hence the English common name "black boy" ).

Many hundreds of animal species were observed on Xanthorrhoea species, but little is known about their interactions. However, some types of grass trees are toxic to animals.

Use

The Australian Aborigines have used Xanthorrhoea species varied. Thus, the eponymous yellow Akaroidharz that flows from the root, used by the Aborigines as an adhesive. The flowers can be fermented into an alcoholic drink.

Some species are used as stand alone, decorative ornamental plants in frost- free areas in parks and gardens used.

Dissemination

The approximately 28 - Xanthorrhoea species are native only in all states of Australia and in Tasmania. They thrive in temperate to tropical climate.

System

The molecular genetic studies in the last ten years have meant that the family boundaries within the order of asparagus -like ( Asparagales ) have dramatically shifted. The systematics of this genus, subfamily, family, was discussed at length, so it is in the literature often encounter apparent inconsistencies. Shown here is the classification by Mark W. Chase et al. 2009th The Xanthorrhoeaceae Dum family. has been extended to the taxa of the former families Asphodelus ( Asphodelaceae ) and Tagliliengewächse ( Hemerocallidaceae ). Today the Xanthorrhoea are the only genus in 2009 by Mark W. Chase, James L. Reveal & Michael F. Fay newly established subfamily Xanthorrhoeoideae. The basionym for this subfamily is the surname Xanthorrhoeaceae, which was first published in 1829 by Barthélemy Charles Joseph Dumortier in analysis of Familles de Plantes, 60, 62, 103.

The first publication from Xanthorrhoea is debatable: James Edward Smith published in 1797 in JC Dryander: Catalogus Historico - Naturalis Bibliothecae Josephi Banks, 3, 486 the type xanthorrhoea hastilis Sm, but it is debatable whether this release is valid. Otherwise, the valid first description was in 1798 by James Edward Smith, The Characters of Twenty New Genera of Plants, in Transactions of the Linnean Society of London, 4, 219 Another (not valid ) notation Xantorrhoea published in L. Diels bot Jahrb Syst. 35, 1904, 104

Here is a list of about 28 Xanthorrhoea species and their subspecies:

• Xanthorrhoea acanthostachya D.J.Bedford
• Xanthorrhoea acaulis ( Atlee ) DJBedford ( syn.. Xanthorrhoea australis subsp acaulis Atlee )
• Xanthorrhoea arborea R.Br.
• Xanthorrhoea arenaria D.J.Bedford
• Xanthorrhoea australis R.Br.
• Xanthorrhoea bracteata R.Br.
• Xanthorrhoea brevistyla D.A.Herb.
• Xanthorrhoea brunonis Endl. : Xanthorrhoea brunonis Endl. subsp. brunonis
• Xanthorrhoea brunonis subsp. semibarbata D.J.Bedford

• Xanthorrhoea glauca subsp. angustifolia D.J.Bedford
• Xanthorrhoea glauca subsp D.J.Bedford. glauca

• Xanthorrhoea latifolia ( Atlee ) DJBedford subsp. latifolia
• Xanthorrhoea latifolia subsp. maxima D.J.Bedford

• Xanthorrhoea minor subsp. lutea D.J.Bedford
• Xanthorrhoea minor R.Br. subsp. minor

• Xanthorrhoea semiplana F.Muell. subsp. semiplana
• Xanthorrhoea semiplana subsp. tateana ( F.Muell. ) DJBedford ( Syn: Xanthorrhoea tateana F.Muell. )

From the genus Kingia was often assumed that it belongs in this family circle; However, it belongs to the family of Dasypogonaceae.

Swell

• Mark W. Chase, James L. Reveal, Michael F. Fay: A subfamilial classification for the expanded asparagalean families Amaryllidaceae, Asparagaceae and Xanthorrhoeaceae. In: Botanical Journal of the Linnean Society, Volume 161, No. 2, 2009, pp. 132-136, DOI: 10.1111/j.1095-8339.2009.00999.x.
• The Xanthorrhoeaceae in APWebsite family. ( Section systematics and description) seen in April 2010
• The Xanthorrhoeaceae at DELTA family. ( Description section )
• Leslie Watson: Xanthorrhoeaceae in the Western Australian Flora: Online, 2008.
• D. J. Bedford: Xanthorrhoeaceae. In: Gwen J. Harden (ed.): Flora of New South Wales, Volume 4, New South Wales Univ. Press, Kensington 1993, ISBN 0-86840-188-9, pp. 61ff. , ( Html version online), limited preview in Google Book Search (Section Description )
• D. J. Bedford: Xanthorrhoea. In: AS George (ed.): Flora of Australia Vol 46: Iridaceae to Dioscoreaeceae, 1986, ISBN 0-644-04356-3, pp. 148-169.
• AC Borsboom: Xanthorrhoea: A review of current knowledge with a focus on X. johnsonii and X. latifolia, two Queensland protected plants - in -trade, Wildlife Ecology Unit Environmental Sciences Division, EPA, 2005. (PDF file).