Arctanthemum

Perennials, (2.5–)5–40 cm (taller in fruit, rhizomatous). Stems 1 (per rosette), ascending, usually simple, sometimes branched distally, glabrous or ± woolly (hairs basifixed). Leaves (not marcescent) basal and cauline; alternate; petiolate or sessile (distal); blades (± fleshy) fan-shaped, cuneate, or spatulate to narrowly lanceolate (distally), usually pinnati-palmately lobed (lobes 3–7), ultimate margins coarsely crenate, dentate (at apices of lobes), or entire (distally), faces ± woolly, glabrescent. Heads radiate, borne singly or in 2s or 3s. Involucres patelliform to hemispheric, 13–29 mm diam. Phyllaries persistent, (22–)25–34(–44) in 3(–4) series, distinct, lanceolate to oblong, unequal, margins and apices (hyaline and colorless or brownish) scarious. Receptacles dome-shaped (glabrous), epaleate. Ray florets (9–)14–25(–30), pistillate, fertile; corollas white, laminae lance-elliptic or elliptic to oblong or oblong-lanceolate. Disc florets 140–360+, bisexual, fertile; corollas yellow, tubes broadly cylindric, throats campanulate, lobes 5, deltate (without resin sacs). Cypselae cylindro-obconic, ribs 5–8(–10), faces glabrous, usually gland-dotted (pericarps without myxogenic cells or resin sacs; embryo sac development monosporic); pappi 0. x = 9.

Distribution

n North America, n Eurasia (Russia), ne Asia (Pacific coast).

Discussion

Species 1.

C. Oberprieler et al. (pers. comm.) have placed Arctanthemum in their Asian grade (Group II) based on the study by L. E. Watson et al. (2002), distinct from Chrysanthemum (conserved name, syn. Dendranthema); Arctanthemum was also recognized as distinct by K. Bremer and C. J. Humphries (1993), who included Hulteniella in it. Hulteniella is kept separate here (as done by Oberprieler et al.). In both papers, three species were recognized within Arctanthemum, as done by N. N. Tzvelev when he established the genus. Later, Tzvelev (1987) placed A. hultenii in synonymy with A. arcticum subsp. polare (as here). The status of the remaining species, A. kurilense (Tzvelev) Tzvelev, which has not been reported for North America, appears dubious and the taxon is not recognized here; it may belong with A. arcticum subsp. arcticum.

Selected References

Tzvelev, N. N. 1987. Arctanthemum. In: A. I. Tolmatchew, ed. 1960–1987. Flora Arctica URSS. 10 vols. Moscow and Leningrad. Vol. 10, pp. 114–117.

Lower Taxa

Arctanthemum arcticum