Arruda in H. Koster

in H. Koster, Trav. Brazil, 495. 1816

Common names: Umbrella thoroughwort
Etymology: Etymology unknown possibly an oblique reference to the leaves as a source of dye like indigo
Treatment appears in FNA Volume 21. Treatment on page 542. Mentioned on page 461, 462.
Perennials, subshrubs, or shrubs [trees, vines], 40–200+ cm. Stems erect, branched. Leaves cauline; mostly opposite (distal sometimes alternate); petiolate; blades usually 3-nerved from bases, mostly deltate or ovate to triangular-lanceolate or lanceolate (lacking internal translucent lenses or streaks), margins entire or dentate, faces glabrous or sparsely hispidulous, puberulent, or strigose, sometimes sparsely to densely gland-dotted. Heads discoid, in corymbiform to paniculiform arrays. Involucres obconic to hemispheric, 2–3 mm diam. Phyllaries persistent (at least outermost), 7–16 in 1–2[–4] series, 3-nerved, ovate to lanceolate, ± equal or unequal. Receptacles flat or convex, epaleate. Florets 3–13[–20]; corollas whitish to pinkish [violet], throats funnelform (lengths ca. 2.5 times diams.); styles: bases sometimes enlarged, glabrous, branches filiform to obscurely clavate. Cypselae prismatic, 5-ribbed, sparsely hispidulous or piloso-strigose, sometimes gland-dotted; pappi persistent, of 30–35, barbellate bristles in 1 series. x = 10.


s, w United States, Mexico, West Indies, Central America, South America.


Species ca. 115 (3 in the flora).




1 Leaf blades ovate to ovate-deltate or ovate-lanceolate, abaxial faces densely gland-dotted Koanophyllon villosum
1 Leaf blades lanceolate to triangular-lanceolate, abaxial faces eglandular or sparsely gland-dotted > 2
2 Leaves usually opposite, sometimes subopposite to alternate on distal 1/3 of stems, blade apices acuminate, adaxial faces glabrous; involucres 4.5–5.5 mm; phyllaries: outermost narrowly lanceolate, glabrous, margins hyaline on proximal 2/3, eciliate Koanophyllon solidaginifolium
2 Leaves opposite, blade apices acute, adaxial faces sparsely strigose to hispidulous; involucres (3–)3.5–4 mm; phyllaries: outermost ovate-elliptic or obovate to narrowly oblong-lanceolate, puberulent, margins herbaceous, usually weakly ciliate Koanophyllon palmeri