Perennials, subshrubs, or shrubs, to 150 cm (rhizomatous, forming clonal colonies, roots fibrous, sometimes adventitious). Stems decumbent to erect, branched ± throughout (sap sticky-resinous). Leaves cauline; opposite; ± petiolate or sessile; blades (usually 1-nerved, sometimes obscurely 3- or 5-nerved) elliptic, linear, oblanceolate, obovate, or ovate (usually coriaceous or succulent), bases ± cuneate, margins entire or toothed (teeth often spine-tipped), faces glabrous or puberulent to villous and/or sericeous. Heads radiate, borne singly or (3–10) in cymiform arrays. Involucres globose or ovoid to hemispheric or broader, (5–)8–13(–18+) mm diam. Phyllaries persistent, 10–45 in 2–3 series (outer larger, elliptic to oblanceolate or ovate, apices acute, cuspidate, obtuse, rounded, or spine-tipped). Receptacles convex, paleate (paleae lanceolate to ovate, ± conduplicate, partially enclosing cypselae, apices often ± pungent). Ray florets 7–30, pistillate, fertile; corollas yellow. Disc florets 20–75, bisexual, fertile; corollas yellow, tubes shorter than funnelform throats, lobes 5, lance-triangular (anthers black with orange glands on connectives). Cypselae (gray to black) ± obcompressed, or obpyramidal and 3- or 4-angled (faces faintly finely reticulate); pappi persistent or tardily falling, (stramineous) coroniform or cupular (3–4-angled). x = 14.
United States, Mexico, West Indies.
Species 3 (3 species, including 1 hybrid, in the flora).
Leaves of Borrichia species are usually heteroblastic: leaves on primary stems are usually ± petiolate (sometimes with spine-tipped teeth on margins of petioles or near bases of blades) and larger and relatively broader than the usually sessile leaves on secondary stems.
|1||Leaves (at least mid cauline): margins entire or dentate to serrate (teeth remote, mostly toward apices), faces glabrous or sericeous; phyllaries (chartaceous in fruiting heads): apices acute, rounded, or obtuse; paleae: apices obtuse to acute||Borrichia arborescens|
|1||Leaves (at least mid cauline): margins usually dentate to serrate, rarely entire, faces usually villous (longer hairs) and/or sericeous (shorter hairs) to glabrate, rarely glabrous; phyllaries: apices cuspidate or spine-tipped; paleae: apices cuspidate or spine-tipped||> 2|
|2||Mid-cauline leaves (petioles or blade bases with spine-tipped teeth): margins dentate to serrate (usually only proximal 1/3–1/2, rarely most, of each margin); phyllaries (often reflexed, swollen in fruit): apices spine-tipped; paleae: apices spine-tipped||Borrichia frutescens|
|2||Mid-cauline leaves: margins dentate or serrate (at least mid portions, often undulate as well); phyllaries: apices cuspidate; paleae: apices cuspidate||Borrichia ×cubana|