Overview

Comprehensive Description

Description

Perennial herbs or subshrubs. Leaves distichous. Inf. a terminal panicle (in ours). Flowers (in ours) actinomorphic, bisexual, borne on articulated pedicels. Tepals 6, in 2 ± equal whorls of 3. Stamens 6 in two whorls of 3. Ovary superior (in ours), 3-locular. Fruit a berry (in ours). Seeds black, without an aril.
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Description

Succulent perennial herbs, some attaining the height of small trees. Stems present or 0. Leaves succulent, often stiff, distichous, borne in rosettes, ovate-acuminate and with a sharp-pointed tip and with hard-toothed or spiny margins. Inflorescence a simple or compound raceme. Bracts scarious, persistent. Flowers bisexual, often zygomorphic, pedicellate. Perianth of 6 lobes, tubular, red, orange, yellow, white or green; tube cylindric; lobes short, fused below, triangular. Stamens 6. Ovary superior, 3-locular. Fruit a 3-angled capsule. Seeds irregularly angled, often winged.
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Evolution and Systematics

Functional Adaptations

Functional adaptation

Compacted leaves form efficient heat insulation: grass tree
 

The leaves of the grass tree serve as efficient heat insulation via compacted arrangement of leaf bases.

     
  "This country [southwestern Australia] is also one of the headquarters of the grass tree…It is neither a grass nor is it a tree. It is a distant relative of the lilies. But it does have very long narrow leaves that resemble grass, and they are born in a great shock on the top of a stem that looks like the trunk of a tree and may be up to ten feet high. However the core of this trunk is not timber but fibre and what seems to be bark is, in fact, the tightly compacted bases of the leaves which are shed annually from beneath the crown as the plant grows higher. These bases are glued together by a copious flow of gum and they form a very efficient heat insulation. Since the plant sheds one ring of leaves annually, counting the rings of bases in this fire-proof jacket gives an indication of age and reveals that the grass trees not only grow only a foot or so in a decade but that a mature one may be about five hundred years old and therefore be the survivor of dozens of fires." (Attenborough 1995:190-191)
  Learn more about this functional adaptation.
  • Attenborough, D. 1995. The Private Life of Plants: A Natural History of Plant Behavior. London: BBC Books. 320 p.
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Functional adaptation

Leaves glued together: grass trees
 

The leaves of the grass tree are glued together at their bases by a large quantity of gum.

   
  "This country [southwestern Australia] is also one of the headquarters of the grass tree…It is neither a grass nor is it a tree. It is a distant relative of the lilies. But it does have very long narrow leaves that resemble grass, and they are born in a great shock on the top of a stem that looks like the trunk of a tree and may be up to ten feet high. However the core of this trunk is not timber but fibre and what seems to be bark is, in fact, the tightly compacted bases of the leaves which are shed annually from beneath the crown as the plant grows higher. These bases are glued together by a copious flow of gum and they form a very efficient heat insulation. Since the plant sheds one ring of leaves annually, counting the rings of bases in this fire-proof jacket gives an indication of age and reveals that the grass trees not only grow only a foot or so in a decade but that a mature one may be about five hundred years old and therefore be the survivor of dozens of fires." (Attenborough 1995:190-191)
  Learn more about this functional adaptation.
  • Attenborough, D. 1995. The Private Life of Plants: A Natural History of Plant Behavior. London: BBC Books. 320 p.
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Functional adaptation

Burning stimulates flowering: grass trees
 

Flowering of grass trees following a fire may be triggered by a huge release of ethylene gas as the trees burn.

     
  "When the flames do come, they quickly burn off the great tuft of leaves [of the grass tree] which incinerate almost instantaneously in a shower of red sparks that fly high into the sky. But the stem, surrounded by its fire-guard remains unharmed and the leaves are quickly regrown. The fire, however, has an additional effect that initially is invisible. As all the vegetation goes up in flames, great quantities of ethylene gas are released. This permeates to the heart of the grass trees and causes a major change within them. A few months after the fire has passed and the leaves have regrown, a vertical green rod emerges from the centre of the leaves. It grows taller and taller until it may double the plant's height. Then, along its length emerge a multitude of tiny white flowers. It may be the production of ethylene on a vast scale following the fire that cues the flowering of almost all the adult grass trees in the bushland." (Attenborough 1995:191)
  Learn more about this functional adaptation.
  • Attenborough, D. 1995. The Private Life of Plants: A Natural History of Plant Behavior. London: BBC Books. 320 p.
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
Specimen Records:960
Specimens with Sequences:1459
Specimens with Barcodes:1416
Species:362
Species With Barcodes:359
Public Records:858
Public Species:338
Public BINs:0
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Barcode data

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Wikipedia

Xanthorrhoeaceae

Xanthorrhoeaceae is a family of flowering plants in the order Asparagales.[2] Such a family has been recognized by most taxonomists, but the circumscription of the family has varied widely.[3]

As defined by the Angiosperm Phylogeny Group in 2009 (the APG III system), the family consists of three subfamilies: Asphodeloideae, Hemerocallidoideae and Xanthorrhoeoideae. Earlier these three had been treated as separate families, with the Xanthorrhoeaceae sensu stricto consisting only of the genus Xanthorrhoea.[4]

The family has a wide, but scattered distribution throughout the tropics and temperate zones. Many of the species are cultivated as ornamentals. A few are grown commercially for cut flowers. Two species of Aloe are grown for their leaf sap, which has medicinal and cosmetic uses. Xanthorrhoea is endemic to Australia.

In some of the older systems of plant taxonomy, such as the Cronquist system, the plants that now form the family Dasypogonaceae were also considered to belong to this family. Molecular phylogenetic studies have shown that Dasypogonaceae belongs to the commelinids and is therefore not even in the same order as Xanthorrhoeaceae.

Description[edit]

Members of the Xanthorrhoeaceae are diverse, with few characters uniting the three subfamilies currently recognized. The presence of anthraquinones is one common character. The flowers (the inflorescence) are typically borne on a leafless stalk (scape) which arises from a basal rosette of leaves. The individual flowers have jointed stalks (pedicels). A disk of woody tissue (a hypostase) is present at the base of the ovule.[2]

The subfamily Xanthorrhoeoideae contains only the genus Xanthorrhoea, native to Australia. Plants typically develop thick woody stems; the flowers are arranged in a dense spike. Members of the subfamily Asphodeloideae are often leaf succulents, such as aloes and haworthias, although the subfamily also includes ornamental perennials such as red hot pokers (Kniphofia). Members of the subfamily Hemerocallidoideae are varied in habit. Daylilies (Hemerocallis) are one of the widely grown members of this subfamily.[2]

Systematics[edit]

Phylogeny[edit]

The order Asparagales can be divided into a basal paraphyletic group, the "lower Asparagales", which includes the Xanthorrhoeaceae as defined here,[5] and a well-supported monophyletic group of "core Asparagales", comprising Amaryllidaceae sensu lato and Asparagaceae sensu lato.[6] Three separate families were at one time recognized (e.g. in the first APG system of 1998): Asphodelaceae, Hemerocallidaceae and Xanthorrhoeaceae. Molecular phylogenetic studies have shown that the three are closely related,[2][7] although Rudall considered that the combination into a single clade was not supported by morphological analysis.[8] The most recent APG classification, the APG III system of 2009, places the three former families into a single family, the Xanthorrhoeaceae sensu lato. The former families are treated as three subfamilies: Asphodeloideae, Hemerocallidoideae and Xanthorrhoeoideae.[4]

The following phylogenetic tree for Xanthorrhoeaceae sensu lato is based on a molecular phylogenetic analysis of the DNA sequences of the chloroplast genes rbcL, matK, and ndhF.[9] All branches have at least 70% bootstrap support. Of the 36 genera recognized by the authors, 29 were sampled. Eccremis was not sampled, but is added here because it is known to be closely related to Pasithea and is often combined with it. Hodgsoniola belongs somewhere in the grade from Tricoryne to Johnsonia. The unsampled genera, Astroloba, Chortolirion and Gasteria, belong to subfamily Asphodeloideae.[10]

Xanthorrhoeaceae
Asphodeloideae


Asphodelus



Asphodeline







Eremurus



Trachyandra





Kniphofia



Bulbinella







Bulbine



Jodrellia





Haworthia



Aloe







Xanthorrhoeoideae

Xanthorrhoea



Hemerocallidoideae


Simethis



Hemerocallis





Tricoryne




Corynotheca




Caesia




Arnocrinum




Hensmannia




Stawellia



Johnsonia










Eccremis



Pasithea





Phormium





Geitonoplesium



Agrostocrinum






Stypandra



Rhuacophila





Dianella




Thelionema



Herpolirion










History[edit]

The family Xanthorrhoeaceae has had a complex history; its circumscription and placement in an order have varied widely. The expansion to include the subfamilies Asphodeloideae and Hemerocallidoideae first occurred as an option in the APG II system of 2003;[11] earlier references to the Xanthorrhoeaceae relate only to the subfamily Xanthorrhoeoideae. The changes have been a consequence of improvement in molecular and morphological analysis and also a reflection of the increased emphasis on placing families within an appropriate order.[8][12][13]

In the Cronquist system of 1981, members of the Xanthorrhoeaceae were placed in the order Liliales.[14][15] Cronquist had difficulty classifying the less obviously delineated lilioid monocots; consequently, he placed taxa from both the modern orders Asparagales and Liliales into a single family Liliaceae.[8]

The 1986 Flora of Australia was based on Cronquist's classification and placed 10 genera within Xanthorrhoeaceae.[16] Bedford et al. acknowledged at the time that some authors, such as Dahlgren et al. (1985), were segregating the 10 genera into two or three separate families, rather than grouping them all under Xanthorrhoeaceae. A review of the systematics of the group, using anatomical and molecular data, led to the conclusion that four of the 10 genera should be placed in the family Dasypogonaceae and five in the family Lomandraceae, leaving only Xanthorrhoea in Xanthorrhoeaceae prior to the APG expansion.[17] The only stable classification over time has been of the genus Xanthorrhoea, which has remained within Xanthorrhoeaceae. This single genus currently contains 30 species.[2]

Genera[edit]

The genera listed below are from the World Checklist of Selected Plant Families,[18] with the division into subfamilies based on APWeb as of December 2010.

Subfamily Asphodeloideae Burnett  

Subfamily Hemerocallidoideae Lindley  

Subfamily Xanthorrhoeoideae M.W.Chase, Reveal & M.F.Fay

The genus Xeronema is now placed in a separate family, the Xeronemaceae.[19]

References[edit]

  1. ^ Stevens, P. F. "ANGIOSPERM PHYLOGENY WEBSITE, version 12.". Xanthorrhoeaceae. Missouri Botanical Garden. Retrieved 9 July 2013. 
  2. ^ a b c d e "Xanthorrhoeaceae" In: Peter F. Stevens (2001 onwards). Angiosperm Phylogeny Website. In: Missouri Botanical Garden Website. (see external links below)
  3. ^ Ole Seberg. 2007. "Xanthorrhoeaceae pages 406-407. In: Vernon H. Heywood, Richard K. Brummitt, Ole Seberg, and Alastair Culham. Flowering Plant Families of the World. Firefly Books: Ontario, Canada.
  4. ^ a b Chase, M. W.; Reveal, J. L.; Fay, M. F. (August 2009). "A subfamilial classification for the expanded asparagalean families Amaryllidaceae, Asparagaceae and Xanthorrhoeaceae". Botanical Journal of the Linnean Society (The Linnean Society of London) 161 (2): 132–136. doi:10.1111/j.1095-8339.2009.00999.x. 
  5. ^ Rudall, P.; Furness, C.A.; Chase, M.W. & Fay, M.F. (1997), "Microsporogenesis and pollen sulcus type in Asparagales (Lilianae)", Canad. J. Bot. (75): 408–430 
  6. ^ Stevens 2001 onwards: Asparagales
  7. ^ Chase, M. W.; De Bruijn A. Y., Cox A. V., Reeves G., Rudall P., Johnson M. A. T. & Eguiarte L. E. (2000). "Phylogenetics of Asphodelaceae (Asparagales): An analysis of Plastid rbcL and trnL-F DNA sequences". Annals of Botany 86 (5): 935–951. doi:10.1006/anbo.2000.1262. 
  8. ^ a b c Rudall, P. J. (2003). "Unique Flower Structures and Iterative Evolutionary Themes in Asparagales: Insights from a Morphological Cladistic Analysis". The Botanical Review 68 (4): 488–509. doi:10.1663/0006-8101(2002)068[0488:UFSAIE]2.0.CO;2. 
  9. ^ Dion S. Devey, Ilia Leitch, Paula J. Rudall, J. Chris Pires, Yohan Pillon, and Mark W. Chase. 2006. "Systematics of Xanthorrhoeaceae sensu lato, with an emphasis on Bulbine". Aliso 22(Monocots: Comparative Biology and Evolution):345-351. ISSN 0065-6275.
  10. ^ Klaus Kubitski (editor). The Families and Genera of Vascular Plants volume III. Springer-Verlag: Berlin;Heidelberg, Germany. ISBN 978-3-540-64060-8
  11. ^ Angiosperm Phylogeny Group II (2003). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II". Botanical Journal of the Linnean Society 141: 399–436. doi:10.1046/j.1095-8339.2003.t01-1-00158.x. 
  12. ^ Angiosperm Phylogeny Group (APG) (1998). An ordinal classification of the families of flowering plants 85. Annals of the Missouri Botanical Garden. pp. 531–553. 
  13. ^ Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". Botanical Journal of the Linnean Society 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. Retrieved 2010-12-10. 
  14. ^ Cronquist, A. (1981). An Integrated System of Classification of Flowering Plants. New York: Columbia University Press. 
  15. ^ Beadle, N. C. W. (1981). The Vegetation of Australia. London: Cambridge University Press. 
  16. ^ Bedford, D. J.; Lee A. T., Macfarlane T. D., Henderson R. J. F. & George A. S. (1986). 'Xanthorrhoeaceae' in Flora of Australia: Iridaceae to Dioscoreaceae 46. Canberra: Australian Government Publishing Service. pp. 88–171. 
  17. ^ Rudall, P. J. (1996). Systematics of Xanthorrhoeaceae sensu lato: evidence for polyphyly. Chase M. W. Telopea. pp. 629–647. 
  18. ^ Search for "Xanthorrhoeaceae", World Checklist of Selected Plant Families, Royal Botanic Gardens, Kew, retrieved 2013-02-25 
  19. ^ "Xeronema", World Checklist of Selected Plant Families, Royal Botanic Gardens, Kew, retrieved 2013-02-25 
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