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Great St. John's Wort

Hypericum ascyron

Description:

This herbaceous perennial wildflower is 3-5' tall. The erect stems are unbranched, except in the upper-third of each plant. Each stem is light green, glabrous, 4-angled, and slightly winged on the angles. The opposite leaves are up to 4" long and 1½" across; they are lanceolate, lanceolate-ovate, or ovate, smooth along the their margins, and glabrous. The upper surface of each leaf is medium green, while the lower surface is pale green. The leaves are sessile or they clasp the stem slightly. The central stem and lateral upper stems (if any) terminate in cymes of 1-5 flowers. Relative to the size of the flowers, branches of each cyme are rather short. Each flower is about 2" across, consisting of 5 yellow petals, 5 green sepals, numerous yellow stamens (about 100), and a light green pistil with 5 persistent styles. The petals are widely spreading and often rather floppy or contorted; they may develop streaks of white with age. The sepals are lanceolate-ovate and much shorter than the petals. The blooming period occurs during mid-summer and lasts about 2-3 weeks. Each flower is replaced by a large hairless seed capsule up to 1¼" long and ½" across. Each seed capsule is divided into 5 cells; each cell contains numerous small seeds that are narrowly oblongoid, flattened, and black at maturity. The root system is rhizomatous, often forming small colonies of plants.

Habitat:

Habitats are rather variable, but they include woodland openings, wooded slopes, banks of rivers and streams, moist thickets and meadows, river-bottom prairies, and fens. This species is usually found in high quality habitats. It is sometimes cultivated in gardens.

Notes:

The flowers are pollinated primarily by bumblebees, which collect pollen. Smaller bees and other insects may visit the flowers as well, but they are less effective pollinators. Only pollen is available as a reward to floral visitors. Some insects feed on the leaves, flowers, and other parts of this and other Hypericum spp. (St. John's Wort species). These include the caterpillars of the moths Eupithecia miserulata (Common Pug), Melanchra assimilis (Black Arches), Synchlora aerata (Wavy-Lined Emerald), Hyppa xylinodes (Common Hyppa), Nedra ramosula (Gray Half-Spot), and Agonopterix hyperella (Oecophorid Moth sp.). The caterpillars of the butterfly Strymon melinus (Gray Hairstreak) feed on the developing capsules and seeds. Other insects that feed on Hypericum spp. include the aphid Brachysiphum hyperici, and the leaf beetles Pachybrachis relictus and Paria sellata. The foliage is somewhat toxic to mammalian herbivores and usually avoided because it can cause irritation of the gastrointestinal tract. The foliage can also cause a harmful reaction to sunlight in light-skinned animals (e.g., pigs), causing irritation of the skin.

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Aarongunnar
Spotted by
Aarongunnar

Wisconsin, USA

Spotted on Jul 14, 2015
Submitted on Oct 9, 2016

Related Spottings

Hypericum hypericum Hypericum St. John's wort

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European Skipper Plains Clubtail Common Soapwort Queen Anne's Lace

Reference

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