Xanthorrhoeaceae
Encyclopedia
Xanthorrhoeaceae is the botanical name
of a family
of flowering plants in the order
Asparagales
. Such a family has been recognized by most taxonomists, but the circumscription
of the family has varied wildly.
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
.
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.
order Asparagales
, along with Xanthorrhoeaceae.
Molecular DNA sequencing has uncovered several monocot clades, although there still remains an unresolved polytomy between three groups: the lilioid orders, the commelinid clade, and the family Petrosaviaceae
. The main taxonomic issue within the Asparagales
is the placement of Orchidaceae
. Recent research that indicates Orchidaceae to be monophyletic. This places it as a sister taxon to all Asparagales
, notwithstanding research such as Rudall’s morphological analysis, which suggested a close relationship between Orchidaceae
and certain other families within Asparagales
, such as Hypoxidaceae
.
The order Asparagales
is divided into two groups. The lower grade contains early-diverging clades characterised by simultaneous microsporogenesis
; and the higher clade is characterised by successive microsporogenesis. The morphological division between successive and simultaneous microsporogenesis is supported by through molecular analysis in comparing monocot rbcL nucleotide sequences, and plastid trnL-F sequences. The Angiosperm Phylogeny Website
disputes this finding, claiming that placement based on changes in microsporogenesis is unclear. In the lower Asparagales, which has mostly simultaneous microsporogenesis, the successive type is present in Xanthorrhoeaceae, Hypoxidaceae
, Iridaceae
and Orchidaceae
. This change has been described as a reversal from simultaneous to successive, since this particular change is more frequent across the angiosperms.
Even with these findings, simultaneous microsporogenesis continues to be of phylogenic importance within Asparagales.
Rudall carried out a morphological cladistic analysis on Asparagales
, which included an out-group sample of five families of Liliales
. Rudall recognized that restrictions of this type of analysis depends on the broadness of out-group sampling, and the limits of the number of taxa sampled, especially when the lilioid
orders have a high homoplasy of floral and vegetative characteristics. Regardless of these sampling problems, Rudall’s morphological analysis indicates that Asparagales has a monophyletic lower clade, rather than a grade. Rudall confirms Chase et al.’s molecular analysis by placing Xanthorrhoeaceae into the lower group in Asparagales, despite sharing the characteristic of successive microsporogenesis with the higher clade.
Xanthorrhoeaceae has been found to be closely related to Asphodelaceae
and Hemerocallidaceae
, with Xanthorrhoeaceae and Asphodelaceae as sister taxa. There is some uncertainty in the branch of Hemerocallidaceae and the Xanthorrhoeaeace/Asphodelaceae branch, reflected in the 50–79% branch support in the phylogenetic relationships within Asparagales. Rudall, in confirmation of this uncertainty, states that by placing Xanthorrhoeaceae in a clade with Asphodelaceae and Hemerocallidaceae, although supported by molecular analysis, is not supported by morphological analysis; however, Rudall does concede that it shares a thickening meristem with Asphodelaceae.
In order to resolve this uncertainty between Xanthorrhoeaceae, Asphodlaceae and Hemerocallidaceae, it has been suggested that the family Xanthorrhoeaceae is to contain a scheme of three subfamilies: Asphodeloideae, Hemerocallidoideae and Xanthorrhoeoideae.
for Xanthorrhoeaceae sensu lato is based on a molecular phylogenetic analysis of the DNA sequence
s of the chloroplast
gene
s rbcL, matK, and ndhF. All branches have at least 70% bootstrap
support. Twenty-nine of the 36 genera recognized by the authors 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 other 5 unsampled genera, Astroloba, Chortolirion, Gasteria, Lomatophyllum, and Poellnitzia belong to subfamily Asphodeloideae.
Early classification of Xanthorrhoeaceae placed the family in the order Liliaceae
, followed by placement in the order Agavales, alongside the family Agavaceae
. Later classification by Cronquist and Beadle followed more traditional methods. This classification included Xanthorrhoeaceae within the order Liliales
, under the subclass Liliidae
. Cronquist had difficulty classifying the less obviously delineated Lilioid monocots; consequently, taxa from both orders Asparagales and Liliales were placed into a single family Liliaceae
by Cronquist.
Flora of Australia replicated Cronquist's classification, by placing ten genera within Xanthorrhoeaceae. Bedford et al. acknowledged at this time that some authors, such as Dahlgren et al. (1985), were segregating the ten genera into two or three separate families, rather than all grouped under Xanthorrhoeaceae.
A review of the systematics of the group, using anatomical and molecular data has led to the conclusion that the genera Baxteria, Calectasia
, Dasypogon
and Kingia
should be included in the family Dasypogonaceae
, based on the presence of silica bodies found in the epidermal cells of these genera. They also found that Acanthocarpus, Chamaexeros
, Lomandra, Romnalda
and Xerolirion
should be included in the family Lomandraceae, due to similar leaf anatomy. Xanthorrhoea
was found to be placed correctly in Xanthorrhoeaceae, due to its isolated taxonomy.
The classification of the genera contained within the group has changed in light of new molecular analysis (combined rbcL and trnL-F DNA analysis) and morphological analysis (leaf anatomy, silica within cells), as well as through reviewing previous published literature on Xanthorrhoeaceae, as carried out by researchers such as Rudall and Chase et al. The only stable classification over time has been of the genus Xanthorrhoea, which has remained within Xanthorrhoeaceae. This single genus currently contains 30 species.
Xanthorrhoeaceae have sympodial growth, where inflorescences put a kink in the trunk. This occurs when a new growth tip is slightly offset from the trunk’s central axis. This is otherwise known as apical displacement. Sympodial growth occurs in most monocots
Xanthorrhoeaceae has a secondary thickening meristem, which is one of the identifying characteristics unique to Asparagales
The ovary is secondarily superior, which appears to be related to infra-locular septal nectaries, although the position of the ovary is a flexible characteristic in the Asparagales
Botanical name
A botanical name is a formal scientific name conforming to the International Code of Botanical Nomenclature and, if it concerns a plant cultigen, the additional cultivar and/or Group epithets must conform to the International Code of Nomenclature for Cultivated Plants...
of a family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of flowering plants in the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Asparagales
Asparagales
Asparagales is the name of an order of plants, used in modern classification systems such as the APG III system . The order takes its name from the family Asparagaceae and is placed in the monocots. The order has only recently been recognized in classification systems...
. Such a family has been recognized by most taxonomists, but the circumscription
Circumscription (taxonomy)
In taxonomy, circumscription is the definition of the limits of a taxonomic group of organisms. One goal of taxonomy is to achieve a stable circumscription for every taxonomic group. Achieving stability can be simple or difficult....
of the family has varied wildly.
As defined by the Angiosperm Phylogeny Group
Angiosperm Phylogeny Group
The Angiosperm Phylogeny Group, or APG, refers to an informal international group of systematic botanists who came together to try to establish a consensus on the taxonomy of flowering plants that would reflect new knowledge about plant relationships discovered through phylogenetic studies., three...
in 2009 (the APG III system
APG III system
The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy...
), 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
Xanthorrhoea
Xanthorrhoea is a genus of flowering plants native to Australia and a member of family Xanthorrhoeaceae, being the only member of subfamily Xanthorrhoeoideae. The Xanthorrhoeaceae are monocots, part of order Asparagales. There are 28 species and five subspecies of Xanthorrhoea.-Description:All are...
.
The family has a wide, but scattered distribution
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...
throughout the tropics
Tropics
The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately N and the Tropic of Capricorn in the southern hemisphere at S; these latitudes correspond to the axial tilt of the Earth...
and temperate zones. Many of the species are cultivated
Horticulture
Horticulture is the industry and science of plant cultivation including the process of preparing soil for the planting of seeds, tubers, or cuttings. Horticulturists work and conduct research in the disciplines of plant propagation and cultivation, crop production, plant breeding and genetic...
as ornamentals
Ornamental plant
Ornamental plants are plants that are grown for decorative purposes in gardens and landscape design projects, as house plants, for cut flowers and specimen display...
. A few are grown commercially
Commerce
While business refers to the value-creating activities of an organization for profit, commerce means the whole system of an economy that constitutes an environment for business. The system includes legal, economic, political, social, cultural, and technological systems that are in operation in any...
for cut flowers
Floriculture
Floriculture, or flower farming, is a discipline of horticulture concerned with the cultivation of flowering and ornamental plants for gardens and for floristry, comprising the floral industry...
. Two species of Aloe are grown for their leaf sap
Plant sap
Sap is a fluid transported in xylem cells or phloem sieve tube elements of a plant. It transports water and nutrients throughout the plant....
, which has medicinal
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
and cosmetic
Cosmetics
Cosmetics are substances used to enhance the appearance or odor of the human body. Cosmetics include skin-care creams, lotions, powders, perfumes, lipsticks, fingernail and toe nail polish, eye and facial makeup, towelettes, permanent waves, colored contact lenses, hair colors, hair sprays and...
uses. Xanthorrhoea is endemic to Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
In some of the older systems of plant taxonomy, such as the Cronquist system
Cronquist system
The Cronquist system is a taxonomic classification system of flowering plants. It was developed by Arthur Cronquist in his texts An Integrated System of Classification of Flowering Plants and The Evolution and Classification of Flowering Plants .Cronquist's system places flowering plants into two...
, the plants that now form the family Dasypogonaceae
Dasypogonaceae
Dasypogonaceae is a botanical name of a family of flowering plants. Such a family has not been commonly recognized by taxonomists: the plants involved were usually included in the family Xanthorrhoeaceae....
were also considered to belong to this family. Molecular phylogenetic studies
Research
Research can be defined as the scientific search for knowledge, or as any systematic investigation, to establish novel facts, solve new or existing problems, prove new ideas, or develop new theories, usually using a scientific method...
have shown that Dasypogonaceae belongs to the commelinids
Commelinids
In plant taxonomy, commelinids is a name used by the APG III system for a clade within the monocots, which in its turn is a clade within the angiosperms. The commelinids are the only clade that the APG has informally named within the monocots...
and is therefore not even in the same order as Xanthorrhoeaceae.
Genera
The genera listed below are based on APWeb, .Subfamily Asphodeloideae Burnett
|
Subfamily Hemerocallidoideae Lindley
|
Subfamily Xanthorrhoeoideae M. W. Chase, Reveal & M. F. Fay
|
Phylogeny
The classification of Xanthorrhoeaceae sensu stricto has in the past included ten genera, listed in the Flora of Australia by Bedford et al. This has been reduced over time to currently just one genus, Xanthorrhoea; while the other nine genera were placed into other families such as Laxmanniaceae and Dasypogonaceae, these remained in the lilioidLilioid monocot
Lilioid monocots or lilioids is an informal name used for a grade of five monocot orders in which the majority of species have flowers with relatively large, coloured tepals, broadly similar to those of lilies...
order Asparagales
Asparagales
Asparagales is the name of an order of plants, used in modern classification systems such as the APG III system . The order takes its name from the family Asparagaceae and is placed in the monocots. The order has only recently been recognized in classification systems...
, along with Xanthorrhoeaceae.
Molecular DNA sequencing has uncovered several monocot clades, although there still remains an unresolved polytomy between three groups: the lilioid orders, the commelinid clade, and the family Petrosaviaceae
Petrosaviaceae
Petrosaviaceae is the botanical name of a family of flowering plants. Such a family has been recognized by only few taxonomists: the plants involved were usually treated as belonging to the family Liliaceae....
. The main taxonomic issue within the Asparagales
Asparagales
Asparagales is the name of an order of plants, used in modern classification systems such as the APG III system . The order takes its name from the family Asparagaceae and is placed in the monocots. The order has only recently been recognized in classification systems...
is the placement of Orchidaceae
Orchidaceae
The Orchidaceae, commonly referred to as the orchid family, is a morphologically diverse and widespread family of monocots in the order Asparagales. Along with the Asteraceae, it is one of the two largest families of flowering plants, with between 21,950 and 26,049 currently accepted species,...
. Recent research that indicates Orchidaceae to be monophyletic. This places it as a sister taxon to all Asparagales
Asparagales
Asparagales is the name of an order of plants, used in modern classification systems such as the APG III system . The order takes its name from the family Asparagaceae and is placed in the monocots. The order has only recently been recognized in classification systems...
, notwithstanding research such as Rudall’s morphological analysis, which suggested a close relationship between Orchidaceae
Orchidaceae
The Orchidaceae, commonly referred to as the orchid family, is a morphologically diverse and widespread family of monocots in the order Asparagales. Along with the Asteraceae, it is one of the two largest families of flowering plants, with between 21,950 and 26,049 currently accepted species,...
and certain other families within Asparagales
Asparagales
Asparagales is the name of an order of plants, used in modern classification systems such as the APG III system . The order takes its name from the family Asparagaceae and is placed in the monocots. The order has only recently been recognized in classification systems...
, such as Hypoxidaceae
Hypoxidaceae
Hypoxidaceae is the botanical name of a family of flowering plants, placed in the order Asparagales of the monocots.The family has only recently been recognized by taxonomists. The APG III system of 2009 does recognize this family...
.
The order Asparagales
Asparagales
Asparagales is the name of an order of plants, used in modern classification systems such as the APG III system . The order takes its name from the family Asparagaceae and is placed in the monocots. The order has only recently been recognized in classification systems...
is divided into two groups. The lower grade contains early-diverging clades characterised by simultaneous microsporogenesis
Sporogenesis
Sporogenesis is the production of spores in biology. The term is also used to refer to the process of reproduction via spores. Reproductive spores are formed in many eukaryotic organisms, such as plants, algae and fungi, during their normal reproductive life cycle...
; and the higher clade is characterised by successive microsporogenesis. The morphological division between successive and simultaneous microsporogenesis is supported by through molecular analysis in comparing monocot rbcL nucleotide sequences, and plastid trnL-F sequences. The Angiosperm Phylogeny Website
Angiosperm Phylogeny Website
Angiosperm Phylogeny Website is a well-known web site dedicated to research on Angiosperm phylogeny and taxonomy.The site is hosted by the Missouri Botanical Garden website and maintained by researcher Peter F. Stevens, who is a member of the Angiosperm Phylogeny Group...
disputes this finding, claiming that placement based on changes in microsporogenesis is unclear. In the lower Asparagales, which has mostly simultaneous microsporogenesis, the successive type is present in Xanthorrhoeaceae, Hypoxidaceae
Hypoxidaceae
Hypoxidaceae is the botanical name of a family of flowering plants, placed in the order Asparagales of the monocots.The family has only recently been recognized by taxonomists. The APG III system of 2009 does recognize this family...
, Iridaceae
Iridaceae
The Iris family or Iridaceae is a family of perennial, herbaceous and bulbous plants included in the monocot order Asparagales, taking its name from the genus Iris. Almost worldwide in distribution and one of the most important families in horticulture, it includes more than 2000 species...
and Orchidaceae
Orchidaceae
The Orchidaceae, commonly referred to as the orchid family, is a morphologically diverse and widespread family of monocots in the order Asparagales. Along with the Asteraceae, it is one of the two largest families of flowering plants, with between 21,950 and 26,049 currently accepted species,...
. This change has been described as a reversal from simultaneous to successive, since this particular change is more frequent across the angiosperms.
Even with these findings, simultaneous microsporogenesis continues to be of phylogenic importance within Asparagales.
Rudall carried out a morphological cladistic analysis on Asparagales
Asparagales
Asparagales is the name of an order of plants, used in modern classification systems such as the APG III system . The order takes its name from the family Asparagaceae and is placed in the monocots. The order has only recently been recognized in classification systems...
, which included an out-group sample of five families of Liliales
Liliales
Liliales is an order of monocotyledonous flowering plants. This order of necessity includes the family Liliaceae, but both the family and the order have had a widely disputed history, with the circumscription varying greatly from one taxonomist to another...
. Rudall recognized that restrictions of this type of analysis depends on the broadness of out-group sampling, and the limits of the number of taxa sampled, especially when the lilioid
Lilioid monocot
Lilioid monocots or lilioids is an informal name used for a grade of five monocot orders in which the majority of species have flowers with relatively large, coloured tepals, broadly similar to those of lilies...
orders have a high homoplasy of floral and vegetative characteristics. Regardless of these sampling problems, Rudall’s morphological analysis indicates that Asparagales has a monophyletic lower clade, rather than a grade. Rudall confirms Chase et al.’s molecular analysis by placing Xanthorrhoeaceae into the lower group in Asparagales, despite sharing the characteristic of successive microsporogenesis with the higher clade.
Xanthorrhoeaceae has been found to be closely related to Asphodelaceae
Asphodelaceae
Asphodeloideae is a subfamily of the monocot family Xanthorrhoeaceae in the order Asparagales. It has previously been treated as a separate family, Asphodelaceae. The subfamily name is derived from the generic name of the type genus, Asphodelus...
and Hemerocallidaceae
Hemerocallidaceae
Hemerocallidoideae is the botanical name of a subfamily of flowering plants, part of the family Xanthorrhoeaceae sensu lato in the monocot order Asparagales according to the APG system of 2009. Earlier classification systems treated the group as a separate family, the Hemerocallidaceae. The name...
, with Xanthorrhoeaceae and Asphodelaceae as sister taxa. There is some uncertainty in the branch of Hemerocallidaceae and the Xanthorrhoeaeace/Asphodelaceae branch, reflected in the 50–79% branch support in the phylogenetic relationships within Asparagales. Rudall, in confirmation of this uncertainty, states that by placing Xanthorrhoeaceae in a clade with Asphodelaceae and Hemerocallidaceae, although supported by molecular analysis, is not supported by morphological analysis; however, Rudall does concede that it shares a thickening meristem with Asphodelaceae.
In order to resolve this uncertainty between Xanthorrhoeaceae, Asphodlaceae and Hemerocallidaceae, it has been suggested that the family Xanthorrhoeaceae is to contain a scheme of three subfamilies: Asphodeloideae, Hemerocallidoideae and Xanthorrhoeoideae.
Phylogenetic tree
The following phylogenetic treePhylogenetic tree
A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics...
for Xanthorrhoeaceae sensu lato is based on a molecular phylogenetic analysis of the DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
s of the chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s rbcL, matK, and ndhF. All branches have at least 70% bootstrap
Bootstrapping (statistics)
In statistics, bootstrapping is a computer-based method for assigning measures of accuracy to sample estimates . This technique allows estimation of the sample distribution of almost any statistic using only very simple methods...
support. Twenty-nine of the 36 genera recognized by the authors were sampled
Sample (material)
In general, a sample is a limited quantity of something which is intended to be similar to and represent a larger amount of that thing. The things could be countable objects such as individual items available as units for sale, or a material not countable as individual items. Samples of countable...
. 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
Evolutionary grade
In alpha taxonomy, a grade refers to a taxon united by a level of morphological or physiological complexity. The term was coined by British biologist Julian Huxley, to contrast with clade, a strictly phylogenetic unit.-Definition:...
from Tricoryne to Johnsonia. The other 5 unsampled genera, Astroloba, Chortolirion, Gasteria, Lomatophyllum, and Poellnitzia belong to subfamily Asphodeloideae.
Classification
The family Xanthorrhoeaceae has been placed into four different orders over time. According to Rudall this re-classification has been a consequence of improvement in molecular and morphological analysis. Re-classification is also a reflection of the increased emphasis on placing families within an appropriate order.Early classification of Xanthorrhoeaceae placed the family in the order Liliaceae
Liliaceae
The Liliaceae, or the lily family, is a family of monocotyledons in the order Liliales. Plants in this family have linear leaves, mostly with parallel veins but with several having net venation , and flower arranged in threes. Several have bulbs, while others have rhizomes...
, followed by placement in the order Agavales, alongside the family Agavaceae
Agavaceae
Agavoideae is a subfamily of monocot flowering plants in the family Asparagaceae, order Asparagales. It has previously been treated as a separate family, Agavaceae. The group includes many well-known desert and dry zone types such as the agave, yucca, and Joshua tree...
. Later classification by Cronquist and Beadle followed more traditional methods. This classification included Xanthorrhoeaceae within the order Liliales
Liliales
Liliales is an order of monocotyledonous flowering plants. This order of necessity includes the family Liliaceae, but both the family and the order have had a widely disputed history, with the circumscription varying greatly from one taxonomist to another...
, under the subclass Liliidae
Liliidae
Liliidae is a botanical name at the rank of subclass. Circumscription of the subclass will vary with the taxonomic system being used ; the only requirement being that it includes the family Liliaceae....
. Cronquist had difficulty classifying the less obviously delineated Lilioid monocots; consequently, taxa from both orders Asparagales and Liliales were placed into a single family Liliaceae
Liliaceae
The Liliaceae, or the lily family, is a family of monocotyledons in the order Liliales. Plants in this family have linear leaves, mostly with parallel veins but with several having net venation , and flower arranged in threes. Several have bulbs, while others have rhizomes...
by Cronquist.
Flora of Australia replicated Cronquist's classification, by placing ten genera within Xanthorrhoeaceae. Bedford et al. acknowledged at this time that some authors, such as Dahlgren et al. (1985), were segregating the ten genera into two or three separate families, rather than all grouped under Xanthorrhoeaceae.
A review of the systematics of the group, using anatomical and molecular data has led to the conclusion that the genera Baxteria, Calectasia
Calectasia
Calectasia is a genus of flowering plants in the family Dasypogonaceae. They are commonly referred to as Tinsel Lilies, and are endemic to southern Australia.Species include:*Calectasia browneana Keighery, K.W.Dixon & R.L.Barrett...
, Dasypogon
Dasypogon
Dasypogon is a genus of flowering plants in the family Dasypogonaceae. It includes three species....
and Kingia
Kingia
Kingia is a genus of the plant family Dasypogonaceae, consisting of a single species Kingia australis. It has a thick pseudo-trunk consisting of accumulated leaf-bases, with a cluster of long, slender leaves on top. The trunk is usually unbranched, but can branch if the growing tip is damaged...
should be included in the family Dasypogonaceae
Dasypogonaceae
Dasypogonaceae is a botanical name of a family of flowering plants. Such a family has not been commonly recognized by taxonomists: the plants involved were usually included in the family Xanthorrhoeaceae....
, based on the presence of silica bodies found in the epidermal cells of these genera. They also found that Acanthocarpus, Chamaexeros
Chamaexeros
Chamaexeros is a genus of tufted perennial herbs in the family Asparagaceae, subfamily Lomandroideae .Species include:*Chamaexeros fimbriata Benth.*Chamaexeros longicaulis T.D.Macfarl....
, Lomandra, Romnalda
Romnalda
Romnalda is a small genus of monocotyledonous plants in the family Asparagaceae, subfamily Lomandroideae. The name Romnalda is an anagram of Lomandra, a related though more common genus of sedge-like plants...
and Xerolirion
Xerolirion
Xerolirion is a monotypic genus of perennial herbs in the family Asparagaceae, subfamily Lomandroideae. The sole species is Xerolirion divaricata, commonly known as Basil's Asparagus, from Western Australia ....
should be included in the family Lomandraceae, due to similar leaf anatomy. Xanthorrhoea
Xanthorrhoea
Xanthorrhoea is a genus of flowering plants native to Australia and a member of family Xanthorrhoeaceae, being the only member of subfamily Xanthorrhoeoideae. The Xanthorrhoeaceae are monocots, part of order Asparagales. There are 28 species and five subspecies of Xanthorrhoea.-Description:All are...
was found to be placed correctly in Xanthorrhoeaceae, due to its isolated taxonomy.
The classification of the genera contained within the group has changed in light of new molecular analysis (combined rbcL and trnL-F DNA analysis) and morphological analysis (leaf anatomy, silica within cells), as well as through reviewing previous published literature on Xanthorrhoeaceae, as carried out by researchers such as Rudall and Chase et al. The only stable classification over time has been of the genus Xanthorrhoea, which has remained within Xanthorrhoeaceae. This single genus currently contains 30 species.
Biology and Ecology
Xanthorrhoeaceae are easily recognisable, with a dense tuft of long narrow leaves terminating in a stout woody spike. The spike contains a dense inflorescence with small flowers and capsular fruits. The spike can reach 3m or more, a height which would help seed dispersal. The endosperm of the seed is thick walled, a possible evolutionary development due to Australia’s dry climate.Xanthorrhoeaceae have sympodial growth, where inflorescences put a kink in the trunk. This occurs when a new growth tip is slightly offset from the trunk’s central axis. This is otherwise known as apical displacement. Sympodial growth occurs in most monocots
Xanthorrhoeaceae has a secondary thickening meristem, which is one of the identifying characteristics unique to Asparagales
The ovary is secondarily superior, which appears to be related to infra-locular septal nectaries, although the position of the ovary is a flexible characteristic in the Asparagales
Biogeography
Xanthorrhoeaceae are endemic to Australia, with distribution in all States and mainland Territories. Nearly all species occur in regions with rainfall greater than 250 mm per year. Many species have limited ranges, and are often found in isolated clumpsExternal links
- Xanthorrhoeaceae in L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, information retrieval. Version: 9 March 2006. http://delta-intkey.com
- NCBI Taxonomy Browser
- links at CSDL, Texas