Marshallia

Perennials, (10–)20–80(–120) cm (fibrous-rooted, usually with caudices, sometimes rhizomatous). Stems erect, sometimes branched (striate). Leaves basal and/or cauline; alternate; petiolate or sessile; blades (1- or 3-nerved) elliptic, linear, linear-elliptic, linear-oblanceolate, oblanceolate, ovate, or spatulate, margins entire, faces glabrous. Heads discoid, borne singly or in open, corymbiform arrays (peduncles relatively long). Involucres hemispheric to obconic, 10–25+ mm diam. Phyllaries persistent, 12–24 in ± 2 series (lanceolate, linear, oblong, ovate, or rhombic, subequal, herbaceous, midnerves often keeled, proximal margins often scarious). Receptacles conic or convex (usually hollow), paleate (paleae linear to spatulate, distally herbaceous). Ray florets 0. Disc florets (20–)45–90(–160+), bisexual, fertile; corollas pale lavender, pink, or purple, or white, (usually hairy) tubes longer than to nearly equaling throats, lobes 5, lance-linear to linear-oblong (often contorted). Cypselae turbinate or clavate (5-angled, ribs 10, often hairy); pappi persistent, of 5(–6) scarious to membranous (hyaline, sometimes scaberulous) scales. x = 9.

Distribution

s, c, se United States.

Discussion

Species 7 (7 in the flora).

Selected References

Channell, R. B. 1957. A revision of the genus Marshallia (Compositae). Contr. Gray Herb. 81: 41–132.

Watson, L. E. and J. R. Estes. 1990. Biosystematic and phenetic analysis of Marshallia (Asteraceae). Syst. Bot. 15: 403–414.

Lower Taxa

Marshallia caespitosa, Marshallia graminifolia, Marshallia grandiflora, Marshallia mohrii, Marshallia obovata, Marshallia ramosa, Marshallia trinervia

Key

1	Leaves lance-elliptic, lance-linear, linear, or oblanceolate (lengths mostly 13–30 times widths), widths mostly 2–13 mm	> 2
1	Leaves elliptic, lanceolate, oblanceolate, ovate, or spatulate (lengths mostly 3–13 widths), widths 8–33 mm	> 4
2	Corollas usually pale lavender to purple, rarely white; flowering Aug–Sep	Marshallia graminifolia
2	Corollas usually white, sometimes pale lavender; flowering May–Jun	> 3
3	Heads 4–10, 10–25 mm diam	Marshallia ramosa
3	Heads borne singly, 20–32 mm diam	Marshallia caespitosa
4	Leaves mostly cauline, blades ovate	Marshallia trinervia
4	Leaves mostly basal, blades elliptic, lanceolate, oblanceolate, or spatulate	> 5
5	Phyllary apices obtuse; corollas white	Marshallia obovata
5	Phyllary apices acute; corollas pink	> 6
6	Heads 1(–2), 26–45 mm diam	Marshallia grandiflora
6	Heads 2–5(–10), 22–37 mm diam	Marshallia mohrii