''Symphyotrichum'' () is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of over 100 species and naturally occurring hybrids of
herbaceous
Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials.
Definitions of "herb" and "herbaceous"
The fourth edition of t ...
annual
Annual may refer to:
* Annual publication, periodical publications appearing regularly once per year
**Yearbook
** Literary annual
* Annual plant
* Annual report
* Annual giving
* Annual, Morocco, a settlement in northeastern Morocco
* Annuals (b ...
and
perennial
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
plants in the composite family
Asteraceae
The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...
, most which were formerly treated within the genus ''
Aster
Aster or ASTER may refer to:
Biology
* ''Aster'' (genus), a genus of flowering plants
** List of ''Aster'' synonyms, other genera formerly included in ''Aster'' and still called asters in English
* Aster (cell biology), a cellular structure shap ...
''. The majority are
endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
to
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
, but several also occur in the
West Indies
The West Indies is a subregion of North America, surrounded by the North Atlantic Ocean and the Caribbean Sea that includes 13 independent island countries and 18 dependencies and other territories in three major archipelagos: the Greater A ...
,
Central
Central is an adjective usually referring to being in the center of some place or (mathematical) object.
Central may also refer to:
Directions and generalised locations
* Central Africa, a region in the centre of Africa continent, also known as ...
and
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
, as well as in eastern
Eurasia
Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...
. Several species have been introduced to Europe as garden specimens, most notably New England aster (''
Symphyotrichum novae-angliae
(formerly ''Aster novae-angliae'') is a species of flowering plant in the aster family (Asteraceae) native to central and eastern North America. Commonly known as , , or , it is a perennial, herbaceous plant usually between tall and wide ...
'') and New York aster (''
Symphyotrichum novi-belgii
''Symphyotrichum novi-belgii'' (formerly ''Aster novi-belgii''), commonly called New York aster, is a species of flowering plant. It is the type species for '' Symphyotrichum'', a genus in the family Asteraceae, whose species were once conside ...
'').
Description
Brouillet, et al. wrote:
Taxonomy of ''Symphyotrichum'' is difficult. Species are usually heterophyllous
Heteroblasty is the significant and abrupt change in form and function, that occurs over the lifespan of certain plants. Characteristics affected include internode length and stem structure as well as leaf form, size and arrangement. It should no ...
, some strongly so. Individuals in the spring, with basal rosettes, often have leaf shapes quite different from those with cauline
A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...
leaves seen later in the season. Phyllary
In botanical terminology, a phyllary, also known an involucral bract or tegule, is a single bract of the involucre of a composite flower. The involucre is the grouping of bracts together. Phyllaries are reduced leaf-like structures that form one or ...
shape on first- and later-formed heads
A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may no ...
may differ. Individuals may vary considerably in plant size and array development depending upon growing conditions. The genetic diversity within each species also appears considerable.
For all species in the genus, the
ray floret
The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...
s are white, pink, blue, or purple.
Disc floret
The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...
s are yellow to white, becoming pinkish, reddish purple, or brown when mature. There are 5 lobes on the disc florets of all species in the genus.
Taxonomy
German botanist
Christian Gottfried Daniel Nees von Esenbeck
Christian Gottfried Daniel Nees von Esenbeck (14 February 1776 – 16 March 1858) was a prolific German botanist, physician, zoologist, and natural philosopher. He was a contemporary of Goethe and was born within the lifetime of Linnaeus. He de ...
established this genus in 1833 because he thought that a plant he examined, now believed to be a cultivated variety of New York aster (''
Symphyotrichum novi-belgii
''Symphyotrichum novi-belgii'' (formerly ''Aster novi-belgii''), commonly called New York aster, is a species of flowering plant. It is the type species for '' Symphyotrichum'', a genus in the family Asteraceae, whose species were once conside ...
''), which he called ''Symphyotrichum unctuosum'', was sufficiently distinct from the rest of the genus ''
Aster
Aster or ASTER may refer to:
Biology
* ''Aster'' (genus), a genus of flowering plants
** List of ''Aster'' synonyms, other genera formerly included in ''Aster'' and still called asters in English
* Aster (cell biology), a cellular structure shap ...
'' to warrant its own genus. Nees emphasized the uniqueness of this plant in having its
pappus hairs arranged in a coherent, basal ring. This structure is the basis for the scientific name of this genus, which derives from
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
(''sýmphysis'') "growing together" and (''thríks'';
stem
Stem or STEM may refer to:
Plant structures
* Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang
* Stipe (botany), a stalk to support some other structure
* Stipe (mycology), the stem of a mushro ...
''trich-'') "hair". However, this characteristic ring is not generally shared by most New York aster pappi, nor is it characteristic of any other plants included in the modern concept of ''Symphyotrichum''. Regardless, according to the rules of the
(ICN), the timing of the genus' establishment gives it precedence over other names. The genus was resurrected in 1994 by American botanist
Guy L. Nesom
Guy L. Nesom (born August 2, 1945)''U.S. Public Records Index'' Vol 2 (Provo, UT: Ancestry.com Operations, Inc.), 2010. is an American writer and botanist.
Nesom received his Ph.D. in systematic botany from the University of North Carolina in 19 ...
to group together species formerly included in the genus ''Aster'' in order to make modern genera
monophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...
.
Subdivisions
''Symphyotrichum'' has been divided into five
subgenera
In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus.
In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
:
Subgenus ''Ascendentes''
This subgenus includes two species from the western United States and Canada that originated as hybrids between species in the subgenera ''Symphyotrichum'' and ''Virgulus''.
Subgenus ''Astropolium''
This subgenus includes about 10 species found across the Americas in
salt marsh
A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is dominated ...
es and
salt flats Salt flats, Salt flat, Salt Flats, or Salt Flat may refer to: Geology
*Salt pan (geology), a flat expanse of ground covered with salt and other minerals
* Dry lake, an ephemeral lakebed that consists of fine-grained sediments infused with alkali sal ...
.
Subgenus ''Chapmaniana''
This subgenus includes a single species, ''
S. chapmanii'', found in
Alabama
(We dare defend our rights)
, anthem = "Alabama (state song), Alabama"
, image_map = Alabama in United States.svg
, seat = Montgomery, Alabama, Montgomery
, LargestCity = Huntsville, Alabama, Huntsville
, LargestCounty = Baldwin County, Al ...
and
Florida
Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...
.
Subgenus ''Symphyotrichum''
This subgenus includes about 65 species occurring across North America, including a few species in Central America and the Caribbean, with one species also occurring in Eurasia.
Subgenus ''Virgulus''
This subgenus includes about 28 species occurring across North America, including a few species in Central America and the Caribbean.
Distribution
As a whole, ''Symphyotrichum'' is native throughout the Americas, with one species, ''
S. ciliatum'', also native to eastern
Eurasia
Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...
. Several species have been introduced to Europe and other parts of the world. Most species are native to Mexico, the United States, and Canada, with several species occurring in the
West Indies
The West Indies is a subregion of North America, surrounded by the North Atlantic Ocean and the Caribbean Sea that includes 13 independent island countries and 18 dependencies and other territories in three major archipelagos: the Greater A ...
and
Central America
Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
. Most members of subgenus ''Astropolium'' are restricted to South America.
Species
,
Catalogue of Life
The Catalogue of Life is an online database that provides an index of known species of animals, plants, fungi, and microorganisms. It was created in 2001 as a partnership between the global Species 2000 and the American Integrated Taxonomic Info ...
listed 106 accepted species and identified naturally-occurring hybrids, including the following:
* ''
Symphyotrichum ascendens''
(Lindl.) G.L.Nesom – western aster, longleaf aster, intermountain aster
* ''
Symphyotrichum campestre''
(Nutt.) G.L.Nesom – western meadow aster
* ''
Symphyotrichum chilense''
(Nees) G.L.Nesom – Pacific aster, common California aster
* ''
Symphyotrichum cordifolium''
(L.) G.L.Nesom – heartleaf aster, common blue wood aster
* ''
Symphyotrichum defoliatum''
(Parish) G.L.Nesom – San Bernardino aster
* ''
Symphyotrichum depauperatum''
(Fernald) G.L.Nesom – serpentine aster
* ''
Symphyotrichum dumosum''
(L.) G.L.Nesom – bushy aster, rice-button aster,
* ''
Symphyotrichum eatonii''
(A.Gray) G.L.Nesom – Eaton's aster
* ''
Symphyotrichum ericoides''
(L.) G.L.Nesom – white aster, heath aster
* ''
Symphyotrichum falcatum''
(Lindl.) G.L.Nesom – white prairie aster, falcate aster, western heath aster
* ''
Symphyotrichum frondosum''
(Nutt.) G.L.Nesom – short-rayed alkali aster
* ''
Symphyotrichum georgianum
''Symphyotrichum georgianum'' (formerly ''Aster georgianus'') is a rare species of flowering plant in the Asteraceae, the aster family. Its common name is Georgia aster. It is native to the southeastern United States where it is known from Ala ...
''
(Alexander) G.L.Nesom – Georgia aster
* ''
Symphyotrichum greatae''
(Parish) G.L.Nesom – Greata's aster
* ''
Symphyotrichum hallii''
(A.Gray) G.L.Nesom – Hall's aster
* ''
Symphyotrichum laeve
''Symphyotrichum laeve'' (formerly ''Aster laevis'') is a flowering plant native to Canada, the United States, and Coahuila (Mexico). It has the common names of smooth blue aster, smooth aster, smooth-leaved aster, glaucous Michaelmas-daisy and ...
''
(L.) Á.Löve & D.Löve – smooth aster, smooth leaved aster, glaucous aster
* ''
Symphyotrichum lanceolatum
(formerly ''Aster lanceolatus'' and ''Aster simplex'') is a species of flowering plant in the Family (botany), family Asteraceae Native plant, native to North America. Common names include , , and . It is a Perennial plant, perennial, herbac ...
''
(Willd.) G.L.Nesom – panicled aster, tall white aster
* ''
Symphyotrichum lateriflorum''
(L.) Á.Löve & D.Löve – calico aster
* ''
Symphyotrichum lentum''
(Greene) G.L.Nesom – Suisun Marsh aster
* ''
Symphyotrichum novae-angliae
(formerly ''Aster novae-angliae'') is a species of flowering plant in the aster family (Asteraceae) native to central and eastern North America. Commonly known as , , or , it is a perennial, herbaceous plant usually between tall and wide ...
''
(L.) G.L.Nesom – New England aster
* ''
Symphyotrichum novi-belgii
''Symphyotrichum novi-belgii'' (formerly ''Aster novi-belgii''), commonly called New York aster, is a species of flowering plant. It is the type species for '' Symphyotrichum'', a genus in the family Asteraceae, whose species were once conside ...
''
(L.) G.L.Nesom – New York aster
* ''
Symphyotrichum oblongifolium''
(Nutt.) G.L.Nesom – aromatic aster
* ''
Symphyotrichum oolentangiense''
(Riddell) G.L.Nesom – sky-blue aster, azure aster
* ''
Symphyotrichum pilosum
(formerly ''Aster pilosus'') is a perennial, herbaceous, flowering plant in the Asteraceae family native to central and eastern North America. It is commonly called , , , , , , , or . It may reach tall, and its flowers have white ray flor ...
''
(Willd.) G.L.Nesom – hairy aster, frost aster
* ''
Symphyotrichum prenanthoides''
(Muhl. ex Willd.) G.L.Nesom – crooked-stem aster
* ''
Symphyotrichum puniceum
''Symphyotrichum puniceum'' (formerly ''Aster puniceus''), is a species of flowering plant in the family Asteraceae native to eastern North America. It is commonly known as purplestem aster, red-stalk aster, red-stemmed aster, red-stem aster, a ...
''
(L.) Á.Löve & D.Löve – purplestem aster, red-stemmed aster, swamp aster
* ''
Symphyotrichum sericeum
''Symphyotrichum sericeum'' (formerly ''Aster sericeus'') is a species of flowering plant in the family Asteraceae native to central North America. Commonly known as western silver aster, western silvery aster, and silky aster, it is a perenni ...
''
(Vent.) G.L.Nesom – western silver aster, silky aster
* ''
Symphyotrichum shortii
''Symphyotrichum shortii'' (formerly ''Aster shortii''), commonly called Short's aster, is a species of flowering plant in the family Asteraceae. It is native to North America, where it is primarily found in interior areas east of the Mississi ...
''
(Lindl.) G.L.Nesom – Short's aster
* ''
Symphyotrichum subulatum''
(Michx.) G.L.Nesom – eastern annual saltmarsh aster
Reproduction
Ray florets in the ''Symphyotrichum'' genus are exclusively female, each having a
pistil
Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ''pistils'' ...
(with
style
Style is a manner of doing or presenting things and may refer to:
* Architectural style, the features that make a building or structure historically identifiable
* Design, the process of creating something
* Fashion, a prevailing mode of clothing ...
,
stigma, and
ovary
The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...
) but no
stamen
The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filame ...
. Ray florets accept
pollen
Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...
and each can develop a
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
, but they produce no pollen.
Each ray floret has three
petal
Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...
s which are fused together to form a corolla. The floret has one ovary at the bottom, and this ovary contains one
ovule
In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...
. The ovary has an attached style that extends outward from between the ray floret corolla and the rest of the flower head. As the ray floret is blooming, the stigma at the top of the style splits into two lobes to allow pollen to access the ovary.
Disk florets in the ''Symphyotrichum'' genus are
androgynous
Androgyny is the possession of both masculine and feminine characteristics. Androgyny may be expressed with regard to biological sex, gender identity, or gender expression.
When ''androgyny'' refers to mixed biological sex characteristics i ...
, each with both male (stamen,
anther
The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filam ...
s, and
filaments) and female reproductive parts; thus, a disk floret produces pollen and can develop a seed. The disk floret has five petals, sometimes referred to as ''lobes'', which are fused into its own corolla in the shape of a tube.
The male stamen is inside the tube-shaped corolla of the disk floret. It has five anthers, five filaments, and produces pollen. The anthers and filaments are readily visible as separate entities in non-Asteraceae species. Here, they are fused together to form a cylinder, or tube, with their pollen on the inside only. This male anther cylinder surrounds the female style and stigma. As the style is maturing, it elongates up through the anther cylinder, gathering the pollen on its stigma along the way.
The ovary is at the bottom of the disk floret style. As with the ray floret, the disk floret stigma has two lobes that are fused together. The disk floret's stigma stays closed while pollen is on it, keeping its ovary safe from self-pollination. After the pollen has been collected and carried off by one or more pollinators, the stigma begins to split into two lobes, opening the style so that the disk floret ovary becomes accessible to receive pollen from another plant.
Notes
Citations
References
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External links
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{{Taxonbar, from=Q2629596
Asteraceae genera
Taxa named by Christian Gottfried Daniel Nees von Esenbeck