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marsh St. John's wort, millepertuis de virginie, Virginia marsh-St. John's-wort

Habit Herbs erect, 2–7 dm, sometimes with ascending branches distally.
Stems

internodes 4-lined or 4-angled at first, then terete.

Leaves

sessile, sometimes amplexicaul;

blade usually ovate or triangular-ovate to elliptic or oblong, rarely oblanceolate, 20–65 × 10–22(–30) mm, base shallowly cordate, apex usually rounded, rarely obtuse to retuse, gland dots laminar (relatively dense, large) and intramarginal (relatively small).

Inflorescences

laxly cylindric to pyramidal, 3–15-flowered from terminal node, sometimes with subsidiary inflorescences from to 4 proximal nodes and flowering branches from to 6 further nodes.

Flowers

10–15 mm diam.;

sepals oblong to elliptic-oblong or oblong-lanceolate, 4–7(–8) × 1–2 mm, apex acute to acuminate;

petals oblong-elliptic to oblanceolate, 6–9(–10) mm;

stamen fascicles 4–6.5 mm;

filaments 1/5 connate;

styles 2–3.5 mm.

Capsules

cylindric to ellipsoid or ovoid-ellipsoid, (8–)9–10(–12) × 4–5 mm, apex acute.

Seeds

0.5–1.2 mm.

2n

= 38.

Triadenum virginicum

Phenology Flowering summer–fall (Jul–Oct).
Habitat Swamps, marshy shores, poor fens
Elevation 0–500 m (0–1600 ft)
Distribution
from FNA
AL; AR; CT; DC; DE; FL; GA; IL; IN; KY; LA; MA; MD; ME; MI; MS; NC; NH; NJ; NY; OH; PA; RI; SC; TN; TX; VA; VT; WI; WV; NS; ON
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Discussion

Triadenum virginicum is the most widely distributed North American species of Triadenum. In the southwestern part of its range, the leaves are longer and narrower, approaching those of T. tubulosum and T. walteri; it is nearly always distinguishable from the northern T. fraseri by the sepals and styles (see key).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 6, p. 103.
Parent taxa Hypericaceae > Triadenum
Sibling taxa
T. fraseri, T. tubulosum, T. walteri
Synonyms Hypericum virginicum, Elodes campanulata, E. campanulata var. emarginata, E. virginica, Gardenia virginica, Hypericum campanulatum, H. enneandrum, Martia campanulata
Name authority (Linnaeus) Rafinesque: Fl. Tellur. 3: 79. (1837)
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