Amberboa (Per.) Less., Syn. Gen. Compos. 8. 1832; Keil, Fl. North Amer. @ eFloras.org 21: 172; Amberboa Vaillant, Konigl. Akad. Wiss. Paris. 5: 182. 1754; Shi & Martins, Fl. China @ eFlora.org 20-21: 186; Centaurea L. subgen. Amberboa Persoon, Syn. Pl. 2: 481. 1807.

Herbs, annual or biennial. Stem erect, usually branched from near the base. Leaves basal and cauline, distal cauline leaves smaller and sessile, basal and proximal cauline larger and petiolate; undivided, lyrate or pinnatifid to pinnatisect, margin entire or toothed. Capitula heterogamous, solitary at end of stem and branches, sometimes additionally 1 or few subbasal. Involucre ovoid, glabrous or sparsely arachnoid. Phyllaries many, in several series, imbricate, rigid or subrigid; outer and middle phyllaries broadly rounded; inner phyllaries with scarious apical appendage. Florets many. Outer florets few in 1 row, sterile, corolla expanded, ray-like, 5-20-cleft; inner florets many, in many series, fertile, bisexual, actinomorphic. Corolla yellow or purple; anther bases tailed, apical appendages oblong. Style branches: fused portions with basal node minutely hairy, distinct portions minute. Cypselae (Achenes) oblong, compressed, faces ribbed, wrinkled with long ascending hairs, apex with denticulate rim, basal attachment scar surrounded by conspicuously thickened rim. Pappi persistent, of many scales in several series, distinct, narrow, scarbridulous.

12 species

Amberboa moschata (L.) DC., Prodr. 6: 560. 1838; Fl. China @ eFloras.org 20- 21: 186; Fl North Amer. @ eFloras.org 19-21: 170, 173; Centaurea moschata L., Sp. Pl. 2: 909. 1753.

Annual herbs 30-70 cm tall. Stem solitary, branched from near the base; stem and branches sparsely cobwebby floccose (covered with soft wooly hairs). Leaves 10-25 cm x 4-6 cm, glabrous or sparsely floccose; lower stem leaves petiolate; leaf blade spathulate to elliptic, base attenuate, margin serrulate, apex obtuse to acute; middle and upper stem leaves shortly petiolate, leaf blade elliptic to narrowly elliptic, lyrately pinnatipartite, margins dentate to pinnately dissected into linear-lanceolate segments, margins of the segments irregularly dentate; uppermost leaves sessile or subsessile, margins serrulate. Capitula radiant, long pedunculate, ca. 5 cm across, purplish, bluish or white; peduncles up to 12 cm long, ridged, cobwebby floccose or pubescent. Involucres ovoid, ca. 2.5 cm in diameter. Phyllaries in 3-4 series, rigid, imbricate, villous; outer phyllaries ovate, ca. 4 mm x1.8 mm; middle phyllaries ovate to broadly ovate, 5-10 mm x 3-9 mm, rigid, imbricate, margin scarious; inner phyllaries linear-oblong, ca. 10 mm x 3-4 mm with ovate to orbicular apical appendage. Peripheral or radiant florets: Few in number, 10- 12, in one series, sterile, bilateral, funnel-shaped with distal expanded ray-like limb ca. 25 mm x 8 mm, 10-20-cleft and proximal (basal) narrow cylindrical tube-like part, ca. 1.5 cm long. Ovary and pappi inconspicuous; stamens absent. Inner florets: Many, in many rows, discoid, fertile, ca. 3 cm long. Corolla ca. 4 cm long, the proximal narrow part larger or nearly equal to distal funnelform throat, tubular; corolla lobes 5, ca. 4 mm long, narrow, erect. Anther bases tailed. Ovary ca. 2 mm long, pubescent; style ca. 2.8 cm long, bifid; style branches: fused portion with basal node, minutely hairy. Cypselae (Achenes) ca. 5 mm long, brown, cylindric, ribbed, densely white villous. Pappus many, ca. 5 mm long, scaly.

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