''Euthamia'' is a genus of
flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of ...
s in the 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 ...
.
[Tropicos, Euthamia (Nutt.) Cass.]
/ref> They are known as goldentops[''Euthamia''.]
USDA Plants. and grass-leaved goldenrods.[''Euthamia'': Grass-leaved goldenrods.]
Astereae Lab. University of Waterloo.
The species were formerly classed in genus ''''. They were separated on the basis of morphological differences, such as the arrangement of the flower heads
A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...
in the inflorescence and the glands on the leaves, and of DNA data.[''Euthamia''.]
Flora of North America. Authors have recognized 5 to 10 species.[ They are native to North America, but certain species are introduced in Europe and Asia.][
These species are quite variable in appearance, the variation often influenced by environmental conditions. In general, they are ]rhizomatous
In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow h ...
perennial herbs or subshrubs
A subshrub (Latin ''suffrutex'') or dwarf shrub is a short shrub, and is a woody plant. Prostrate shrub is a related term. "Subshrub" is often used interchangeably with "bush".Jackson, Benjamin, Daydon; A Glossary of Botanic Terms with their De ...
growing erect stems tall. The stems are hairy to hairless and branching or unbranched. The leaves are alternately arranged along the stem. They are linear to lance-shaped, smooth-edged, hairy to hairless, and gland-dotted, if sometimes sparsely. The flower heads are solitary or borne in a dense or spreading array. The back of the head is layered in phyllaries
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 ...
which may be resinous. There are 7 to 22 yellow ray florets, sometimes more, and several yellow disc florets. The fruit is a rough-textured cypsela tipped with a pappus of white bristles.[
''Euthamia'' species are used as food plants by the ]larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
Th ...
e of some Lepidoptera species including '' Coleophora intermediella'', which feeds exclusively on ''E. graminifolia''.
; Species[Biota of North America Program 2013 county distribution maps]
/ref>
* '' Euthamia caroliniana'' (syn. ''E. tenuifolia'') – coastal plain goldentop, slender goldentop – Coastal Plain from Texas to Nova Scotia; also Great lakes region
* ''Euthamia graminifolia
''Euthamia graminifolia'', the grass-leaved goldenrod or flat-top goldentop, is a North American species of plants in the family Asteraceae.
It is native to much of Canada (from Newfoundland to British Columbia), and the northern and eastern Uni ...
'' – common goldentop, flat-top goldentop – northern + eastern US, mostly Great Lakes and Northeast; much of Canada
* '' Euthamia gymnospermoides'' – Great Plains goldentop, Texas goldentop – Great Plains + Great Lakes from Texas to Ontario
* '' Euthamia leptocephala'' – Mississippi Valley goldentop, bushy goldentop – south-central US, Texas to Georgia to Illinois
* '' Euthamia minor'' – southeastern US
* '' Euthamia occidentalis'' – western goldentop, western goldenrod – western Canada, western half of US, northwestern Mexico
References
{{Taxonbar, from=Q5226884
Asteraceae genera
Flora of North America
Taxa named by Henri Cassini