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Eurybia (botanical genus)
Encyclopedia
Eurybia is a genus
of plants in the composite family
that were previously included in the genus Aster. All species are native to North America
, though some are also present in northern Eurasia
. There are 23 species in the genus including 1 hybrid. The name was first applied by Alexandre de Cassini
in 1820. The name is derived from Ancient Greek
ευρυς (eurys), meaning wide, and βαιος (baios), meaning few, perhaps in reference to the small number of relatively wide ray florets.
s that grow from 10 to 120 cm in height. They have rhizome
s which can either be long, slender or short and thick or sometimes corm
oid, all of which often become woody. The stems can be ascending to erect and are typically simple, though they are in rare cases they branch proximally, i.e. near the point of attachment. They can be glabrous to more or less densely hairy, and are generally eglandular, meaning they lack gland
s, though they can sometimes be stipitate-glandular, meaning glands are present on a stipe
.
The leaves
are always alternate. Both basal and cauline leaves, i.e. leaves growing on the stem, are present, and these may be either sessile or petiolate, meaning lacking or having a leaf stalk
. The blades of the leaves may be anything from cordate, ovate, obovate, elliptic, or oblong in shape to spatulate, oblanceolate, or lanceolate. They are usually gradually reduced distally, meaning they taper towards the apex. The leaf margins can be entire or serrate, i.e. toothed, though they may also occasionally be spinulose-serrate, that is being toothed with small spines. The leaf surfaces are glabrate to hairy and are usually eglandular, though they may sometimes be stipitate-glandular.
The capitula
, or flower heads, are radiate and typically appear in corymbiform arrays, but in rare cases they may be borne singly. The involucre
s, the bract
s at the base of the flower heads, are cylindro-campanulate, meaning bell-shaped, to broadly campanulate and measure from 4 to 14 and exceptionally to 16 mm long by 4 to more than 25 mm wide. The phyllaries, that is the individual bracts that make up the involucres, number from 20 up to 140 in 3 to 7 series and are single nerved. They are usually rounded adaxially, i.e. towards their upper-side, but are sometimes low-keeled. Their shape is unequal and broadly ovate or oblong to oblanceolate, lanceolate, or linear. The bases of the phyllaries are indurate, or hardened, and rarely wholly foliaceous, meaning leaf-like in appearance. Their margins are narrowly scarious, meaning membranous and dry, or occasionally herbaceous, and often ciliolate, i.e. having minute cilia. The apices, or terminal ends, are obtuse to acute, while the surfaces are glabrous (hairless), somewhat strigillose (with stiff, slender bristles), puberulent (very finely haired), scabrellous (having small rough hairs), strigoso-villous (with stiff soft hairs), or villous (having soft shaggy hairs), and occasionally they are more or less stipitate-glandular.
The receptacles, the stalks that attach to the florets, are flat to slightly convex, pitted and epaleate, i.e. lacking palea, dry scale-like bracts. The ray florets, the long petal-like appendages, number between 5 and 60 and are pistillate and fertile. Their corollas are white to purple in colour and coil at maturity. The disc florets, the tiny flowers at the center of the flower structure, number from 8 all the way up to 260 and are bisexual and fertile. Their corollas are yellow, though they become purple at maturity, and may be barely to abruptly ampliate, meaning enlarged. The corolla tubes are either shorter or longer than the throats, which are funnelform to campanulate. They have 5 lobes, which are usually erect to spreading or occasionally somewhat reflexed, and are deltate, triangular, or lanceolate.
The style
-branch appendages are lanceolate in shape. The fruit
s are cypselae, which are cylindro-obconic (cylindrically reverse-conical) to fusiform (tapering at both ends) in shape, and are often somewhat compressed. They have 7 to 12 and exceptionally up 18 nerves with surfaces that are eglandular and glabrous or sparsely to densely strigillose. The pappi
are persistent and are made up of 35 to 70 or more bristles that are reddish, orange, cinnamon, tawny, tan, yellowish, or pinkish in colour. The bristles are unequal, soft to stiff, barbellate (finely barbed) or barbellulate (barbed with diminutive barbs) and often apically somewhat clavate, or club shaped. They appear in 2 to 4 series.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of plants in the composite family
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
that were previously included in the genus Aster. All species are native to North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, though some are also present in northern Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
. There are 23 species in the genus including 1 hybrid. The name was first applied by Alexandre de Cassini
Alexandre de Cassini
Count Alexandre Henri Gabriel de Cassini was a French botanist and naturalist, who specialised in the sunflower family ....
in 1820. The name is derived from Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
ευρυς (eurys), meaning wide, and βαιος (baios), meaning few, perhaps in reference to the small number of relatively wide ray florets.
Description
All species within the genus are perennialPerennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
s that grow from 10 to 120 cm in height. They have rhizome
Rhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...
s which can either be long, slender or short and thick or sometimes corm
Corm
A corm is a short, vertical, swollen underground plant stem that serves as a storage organ used by some plants to survive winter or other adverse conditions such as summer drought and heat ....
oid, all of which often become woody. The stems can be ascending to erect and are typically simple, though they are in rare cases they branch proximally, i.e. near the point of attachment. They can be glabrous to more or less densely hairy, and are generally eglandular, meaning they lack gland
Gland
A gland is an organ in an animal's body that synthesizes a substance for release of substances such as hormones or breast milk, often into the bloodstream or into cavities inside the body or its outer surface .- Types :...
s, though they can sometimes be stipitate-glandular, meaning glands are present on a stipe
Stipe (botany)
In botany, a stipe is a stalk that supports some other structure. The precise meaning is different depending on which taxonomic group is being described....
.
The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are always alternate. Both basal and cauline leaves, i.e. leaves growing on the stem, are present, and these may be either sessile or petiolate, meaning lacking or having a leaf stalk
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
. The blades of the leaves may be anything from cordate, ovate, obovate, elliptic, or oblong in shape to spatulate, oblanceolate, or lanceolate. They are usually gradually reduced distally, meaning they taper towards the apex. The leaf margins can be entire or serrate, i.e. toothed, though they may also occasionally be spinulose-serrate, that is being toothed with small spines. The leaf surfaces are glabrate to hairy and are usually eglandular, though they may sometimes be stipitate-glandular.
The capitula
Capitulum
The term Capitulum can refer to several things:*In botany, a type of flower head where the bracts are located under the basis, such as a daisy's*Also in botany, the top of a Sphagnum moss plant with compact clusters of young branches....
, or flower heads, are radiate and typically appear in corymbiform arrays, but in rare cases they may be borne singly. The involucre
Involucre
Involucre may refer to* involucral bract, a bract, bract pair, or whorl of bracts surrounding a flower or inflorescence* a term sometimes misused for the cupule surrounding developing nuts in the Fagaceae...
s, the bract
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
s at the base of the flower heads, are cylindro-campanulate, meaning bell-shaped, to broadly campanulate and measure from 4 to 14 and exceptionally to 16 mm long by 4 to more than 25 mm wide. The phyllaries, that is the individual bracts that make up the involucres, number from 20 up to 140 in 3 to 7 series and are single nerved. They are usually rounded adaxially, i.e. towards their upper-side, but are sometimes low-keeled. Their shape is unequal and broadly ovate or oblong to oblanceolate, lanceolate, or linear. The bases of the phyllaries are indurate, or hardened, and rarely wholly foliaceous, meaning leaf-like in appearance. Their margins are narrowly scarious, meaning membranous and dry, or occasionally herbaceous, and often ciliolate, i.e. having minute cilia. The apices, or terminal ends, are obtuse to acute, while the surfaces are glabrous (hairless), somewhat strigillose (with stiff, slender bristles), puberulent (very finely haired), scabrellous (having small rough hairs), strigoso-villous (with stiff soft hairs), or villous (having soft shaggy hairs), and occasionally they are more or less stipitate-glandular.
The receptacles, the stalks that attach to the florets, are flat to slightly convex, pitted and epaleate, i.e. lacking palea, dry scale-like bracts. The ray florets, the long petal-like appendages, number between 5 and 60 and are pistillate and fertile. Their corollas are white to purple in colour and coil at maturity. The disc florets, the tiny flowers at the center of the flower structure, number from 8 all the way up to 260 and are bisexual and fertile. Their corollas are yellow, though they become purple at maturity, and may be barely to abruptly ampliate, meaning enlarged. The corolla tubes are either shorter or longer than the throats, which are funnelform to campanulate. They have 5 lobes, which are usually erect to spreading or occasionally somewhat reflexed, and are deltate, triangular, or lanceolate.
The style
Gynoecium
Gynoecium is most commonly used as a collective term for all carpels in a flower. A carpel is the ovule and seed producing reproductive organ in flowering plants. Carpels are derived from ovule-bearing leaves which evolved to form a closed structure containing the ovules...
-branch appendages are lanceolate in shape. The fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
s are cypselae, which are cylindro-obconic (cylindrically reverse-conical) to fusiform (tapering at both ends) in shape, and are often somewhat compressed. They have 7 to 12 and exceptionally up 18 nerves with surfaces that are eglandular and glabrous or sparsely to densely strigillose. The pappi
Pappus (flower structure)
The pappus is the modified calyx, the part of an individual disk, ray or ligule floret surrounding the base of the corolla, in flower heads of the plant family Asteraceae. The pappus may be composed of bristles , awns, scales, or may be absent. In some species, the pappus is too small to see...
are persistent and are made up of 35 to 70 or more bristles that are reddish, orange, cinnamon, tawny, tan, yellowish, or pinkish in colour. The bristles are unequal, soft to stiff, barbellate (finely barbed) or barbellulate (barbed with diminutive barbs) and often apically somewhat clavate, or club shaped. They appear in 2 to 4 series.