Arnoglossum

Rafinesque

Fl. Ludov., 64. 1817

Common names: Indian plantain
Etymology: Greek arnos, lamb, and glossum, tongue ancient name for some species of Plantago
Synonyms: Conophora (de Candolle) NieuwlandMesadenia Rafinesque
Treatment appears in FNA Volume 20. Treatment on page 622. Mentioned on page 542.
Perennials, 30–300 cm. Stems usually 1, erect (unbranched proximal to heads). Leaves basal and cauline; alternate; petiolate or sessile; blades palmately nerved, mostly cordate, deltate, elliptic, hastate, ovate, or reniform, sometimes lanceolate or lance-linear, margins entire, ± dentate to denticulate, sinuate, or lobed, faces usually glabrous. Heads discoid, in corymbiform arrays. Calyculi 0. Involucres cylindric to turbinate, 2.5–5 mm diam. Phyllaries persistent, 5 in 1–2 series, erect (spreading in fruit), distinct, ovate or oblong to linear (midveins sometimes winged), ± equal, margins scarious (hyaline). Receptacles flat or convex (usually with central cusp 0.5–2 mm), foveolate, epaleate. Ray florets 0. Disc florets 5, bisexual, fertile; corollas usually creamy or greenish white, rarely purplish distally, tubes longer than to equaling campanulate to funnelform throats, lobes 5, spreading or recurved, lanceolate; style branches: stigmatic areas continuous, apices truncate or truncate-penicillate (appendages essentially 0). Cypselae clavate, cylindric, ellipsoid, or ± fusiform, (4–)10–15-ribbed or -nerved, glabrous (resinous); pappi persistent, fragile, or readily falling, of 100–120+, white, smooth or barbellate bristles. x = 28.

Distribution

e North America.

Discussion

Species 8 (8 in the flora).

The name Cacalia Linnaeus has been misapplied to Arnoglossum.

Key

1 Phyllary midveins not winged (leaves ± membranous) > 2
1 Phyllary midveins winged (leaves firm) > 4
2 Basal leaves (and proximal cauline): blades ovate to narrowly lanceolate or lance-linear, margins usually entire Arnoglossum ovatum
2 Basal leaves (and proximal cauline): blades ovate, ovate-cordate, or reniform, margins lobed or dentate > 3
3 Stems smooth to weakly striate (stems and abaxial leaf faces glaucous) Arnoglossum atriplicifolium
3 Stems ridged to angulate (stems and abaxial leaf faces not glaucous) Arnoglossum reniforme
4 Basal leaves: blades ovate to cordate-ovate (bases truncate), margins denticulate; proximal cauline leaves deltate-hastate, margins dentate Arnoglossum diversifolium
4 Basal leaves: blades elliptic, ovate, ovate-oblong, or lance-oblong, margins crenate, crenulate, denticulate, entire, serrulate-denticulate, or sinuate; proximal cauline leaves ovate or elliptic, margins crenulate, denticulate, entire, serrate, or sinuate > 5
5 Phyllary wings (erose) highest at bases (lateral veins of basal leaves appressed to midveins 2–4 cm, then spreading) Arnoglossum album
5 Phyllary wings (entire or sinuate) ± uniform or highest at apices (lateral veins of leaves spreading from bases) > 6
6 Involucres 12–15 mm; corollas (9–)11–12 mm; cauline leaves: margins crenulate Arnoglossum floridanum
6 Involucres 8–14 mm; corollas 7–11.5 mm; cauline leaves: margins crenulate, denticulate, entire, serrulate, or sinuate > 7
7 Involucres (9.5–)10–12(–14) mm; corollas 8–10(–11.5) mm (mid-stem leaves petiolate, bases rounded) Arnoglossum plantagineum
7 Involucres (8–)9.5–10(–12) mm; corollas 7–8(–9.5) mm (mid-stem leaves sessile, bases broadly cuneate) Arnoglossum sulcatum