Montana Field Guide

Mat-forming. Stems prostrate below, rooting at the nodes, ascending above and 2–12 cm high. Leaves elliptic, 3–10 mm long. Flowers few; petals 3–4 mm long; sepals ovate with rounded to acute tips, 2–3 mm long. Capsule 5–6 mm long with yellow seeds (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Montana has 3 native and 1 exotic species of Hypericum. All have leaves that are opposite, sessile, entire, and dotted with translucent glands. Hold a leaf up to the sunlight and see the glands.

Tinker’s-penny - Hypericum anagalloides, native and desirable
* Mature plants are 2-12 cm tall, grow along the ground, and root at leaf nodes.
* Smaller flowers with 5-yellow petals not outlined by black glands and slightly longer than sepals.
* Habitat of wetlands and wet soil in meadows along streams in montane and subalpine zones.

Western St. John’s-wort – Hypericum scouleri, native and desirable
* Mature plants are 5-60 cm tall.
* Large flowers with 5-yellow petals outlined by black glands.
* Sepals are ovate with rounded tips and amber veins.
* Rhizomatous and stoloniferous.
* Habitat is moist to wet areas in meadows, along streambanks, and on ledges from the valleys to the alpine zones.

Common St. John’s-wort - Hypericum perforatum, exotic and noxious
* Size: Mature plants are 25-75 cm tall.
* Flowers: 5-yellow petals outlined by black glands and showy yellow stamens.
* Sepal: 5 linear-lanceolate with acute tips.
* Branches: reddish-colored that help make the plant more noticeable in fall.
* Fruit: a 3-valved capsules with many, tiny seeds.
* Roots: taprooted and rhizomatous.

Larger Canadian St. John’s-wort - Hypericum majus, native and desirable
* Mature plants are 5-25 cm tall, grow decumbant.
* Smaller flowers with 5-yellow petals not outlined by black glands and about as long as sepals.
* Habitat along rivers, ponds, and lakes in valley and montane zones.

Wet soil of meadows along streams, lakes; montane, subalpine (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

POLLINATORS
The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus vagans, Bombus auricomus, Bombus fervidus, Bombus rufocinctus, Bombus ternarius, Bombus terricola, Bombus pensylvanicus, Bombus bimaculatus, Bombus griseocollis, and Bombus impatiens (Heinrich 1976, Thorp et al. 1983, Colla and Dumesh 2010, Colla et al. 2011, Williams et al. 2014).