Bidens alba (Linnaeus) A.P. de Candolle var. radiata (Schultz 'Bipontinus') Ballard ex T.E. Melchert. Common name: Romerillo, Shepherd's-Needle, White-flowered Bidens, White-flowered Spanish-Needles. Habitat: Disturbed areas. Distribution: Adventive from the New World tropics, possibly native in s. FL. Reported for Clarksville, Montgomery County, TN (Kraft 2016).
Origin/Endemic status: Neotropics
Taxonomy Comments: Bidens alba var. radiata is part of a complex that is widespread and native in tropical America. It has been variously split and lumped to varyingly degrees. We here follow the work of the most recent monographer of the group, Ballard (1986), who recognized three species and seven taxa in the complex. Only B. alba var. radiata and B. pilosa (in a narrow sense) are present in our region; the other five taxa occur in Mexico, Central America, and South America.
Synonymy ⓘ: = Bah, Ballard (1986); = Bidens leucantha (L.) Willd. ex Walp. — S13; = Bidens pilosa L. var. radiata Sch.-Bip. — F, Sherff & Alexander (1955); = n/a — C, Pa; < Bidens alba (L.) DC. — Ar, Fl7, Il, NE, POWO, WH3; < Bidens pilosa L. — FNA21, K4, RAB, S, SE1, Lizarazu et al (2024); Bidens pilosa Linnaeus — (basionym)
Links to other floras: < Bidens pilosa - FNA21
Wetland Indicator Status:
- Atlantic and Gulf Coastal Plain: FAC (taxonomic split from wetland indicator species)
- Eastern Mountains and Piedmont: FACW (taxonomic split from wetland indicator species)
- Great Plains: FACW (taxonomic split from wetland indicator species)
- Midwest: FACW (taxonomic split from wetland indicator species)
- Northcentral & Northeast: FACW (taxonomic split from wetland indicator species)
Heliophily ⓘ: 7
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