MONTANA FIELD GUIDE™

Plants: Perennial (possibly biennial), with the sea-green herbage conspicuously glaucous (McGregor et al. 1986), particularly on the stem, and glabrate. Stems often loosely clustered (Cronquist et al. 1994), erect, hollow, 40–100 cm (Lesica 2012), ascending from a short caudex with thick, fibrous, unbranched roots (McGregor et al. 1986).

Leaves: Thick and somewhat succulent (Cronquist et al. 1994); basal and lower stem leaves long-petiolate, pinnately-veined, the blades somewhat elliptic, oblanceolate (McGregor et al. 1986) or lanceolate, smooth-margined or slightly serrate, 2–20 cm in length (Lesica 2012), and 2-8(10) cm in width, length approximately twice the width; petiole similar in length to the blade; middle and upper stem leaves becoming reduced above in progressive fashion until sessile and bract-like (McGregor et al. 1986).

Inflorescence & Heads: Inflorescence a compound, flat-topped cyme (center flower blooming first) (McGregor et al. 1986) of 15 to 50 heads. Heads usually discoid (radiate); involucres 7–10 mm high; phyllaries 8 to 13 (Lesica 2012), of equal size and in a single series (McGregor et al. 1986), glabrous, sometimes black-tipped (Lesica 1986),

(Lesica's contribution adapted from Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)

Flowers July – August (McGregor et al. 1986).

Wet meadows in valleys and foothills (Lesica 2012), up to 8531 ft, withstanding alkali and standing water (Cronquist et al. 1994).

(Lesica's contribution adapted from Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)

The U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) in California tested the potential of using a South African moth, Digitivalva delaireae, as a biological control agent for Cape- or German-ivy, Delairea odorata, which is a South African plant that has become invasive in many western states of the U.S. Alkali-marsh ragwort (a close relative of Cape-ivy) and 36 other Asteraceae species native to the Continental U.S. were tested. Alkali-marsh ragwort was the only test species that experienced damage from the moth. When the insect had no other choice of plant species, a median of 30% of alkali-marsh ragwort’s leaves were damaged from leaf mining. This fell to 2.1% when insects were offered a choice of alkali-marsh ragwort or Cape-ivy. Adult moths also laid their eggs on alkali-marsh ragwort, but no pupation or stem-boring occurred (Mehelis et al. 2015).

POLLINATORS
The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus bifarius, Bombus flavifrons, Bombus frigidus, Bombus huntii, Bombus melanopygus, Bombus mixtus, Bombus sylvicola, Bombus occidentalis, Bombus insularis, Bombus suckleyi, Bombus flavidus, and Bombus kirbiellus (Schmitt 1980, Thorp et al. 1983, Mayer et al. 2000, Wilson et al. 2010, Pyke et al. 2012, Koch et al. 2012, Williams et al. 2014).

Flowers & Fruit: Rays approximately 5, if present (Lesica 2012), fertile, yellow; ligules 3-8 mm in length; disk flowers perfect and fertile (McGregor et al. 1986), 5–6 mm long. Achenes smooth, 2–4 mm in length (Lesica 2012) crowned with pappus consisting of long, white and finely-barbed hairs (McGregor et al. 1986).

(P. Lesica's contribution adapted from Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)

Reported threats to Montana's populations of Alkali-marsh Ragwort include hydrological modifications to wetlands, dewatering, and competition from non-native plant species.