Euthamia caroliniana (L.) Porter & Britton
Common Name: SLENDER GOLDENTOP
Synonym: Euthamia remota
Coefficient of Conservatism: 10
Coefficient of Wetness: -3
Wetness Index: FACW
Physiognomy: Nt P-Forb

Euthamia caroliniana B. S. Walters

E. remota of Michigan Flora.

Moist or marshy sandy to mucky shores, exposed lakebeds, interdunal swales, and occasionally other moist depressions; often abundant in a distinct zone on the recently exposed shore of a softwater lake with fluctuating water levels. Occasionally in much drier habitats such as openings in dry jack pine stands.

We consider all our plants to be one species, pending a thorough revision of this baffling group and use the name E. caroliniana as the oldest applying to the broadly construed species. None of our plants appear to match the western E. gymnospermoides Greene, which has involucres (4–) 4.5–6.2 mm long and disk corollas (3–) 3.3–4.8 mm long. Our specimens all have shorter involucres ca. (3–) 3.5–5 mm long and disk corollas ca. 2.5–3.8 (–4.1) mm long.

Plants from the southwestern Lower Peninsula are most confidently referred to E. caroliniana. Those from the southeastern Lower Peninsula lack the sterile axillary shoots, which are at least somewhat developed in plants from southwestern Michigan. They are presumably equivalent to Solidago moseleyi Fernald, described from Lake Erie. The plants mapped from the Upper Peninsula are a little more puzzling, especially phytogeographically, but there appear to be no tangible differences from Lower Peninsula specimens.

In all parts of the state, plants with the largest leaves a little broader than in E. caroliniana, strongly 3- (or even weakly 5-) veined, but the foliage glutinous on the upper portion of the plant, appear to be intermediate between the two species recognized. Less common intermediate plants have dull foliage with obscure dots, but 1-veined leaves and sometimes a hint of pubescence. Often, intermediates are found on the same shores as less ambiguous E. caroliniana, supporting the oft-claimed assumption of ready hybridization in Euthamia.

Locations

Alger County
Allegan County
Baraga County
Barry County
Berrien County
Calhoun County
Cass County
Chippewa County
Gogebic County
Kalamazoo County
Kent County
Luce County
Marquette County
Monroe County
Muskegon County
Newaygo County
Oceana County
Ottawa County
Roscommon County
Schoolcraft County
Tuscola County
Van Buren County
Wayne County

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 11, 2017. http://www.michiganflora.net/species.aspx?id=327.