The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

lesser marsh St. Johnswort

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

Habit Herbs erect, to 10 dm, sometimes branching from near base, sometimes with ascending branches in distal 1/2+. Herbs erect, 2–7 dm, sometimes with ascending branches distally.
Stems

internodes 2-lined at first, then terete.

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

Leaves

sessile or (distal) subsessile, rarely amplexicaul;

blade narrowly oblong or elliptic to oblanceolate, 50–120(–150) × 10–40(–50) mm, base rounded to truncate or subcordate, apex rounded or rounded-apiculate to retuse, gland dots intramarginal.

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

spiciform-cylindric, 3–7-flowered from terminal node, with sessile or pedunculate inflorescences and flowering branches from to 4 proximal nodes.

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

15 mm diam.;

sepals narrowly oblong, 4–7 × 1–1.5 mm, apex acute to obtuse;

petals elliptic-obovate, 5–8 mm;

stamen fascicles 4–7 mm;

filaments 1/2+ connate;

styles 0.8–1.5 mm.

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, 8–12 × 3.5–4 mm, apex obtuse.

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

Seeds

0.8–1.2 mm.

0.5–1.2 mm.

2n

= 38.

Triadenum tubulosum

Triadenum virginicum

Phenology Flowering late summer–early fall (Aug–Sep). Flowering summer–fall (Jul–Oct).
Habitat Swampy or marshy ground in woods Swamps, marshy shores, poor fens
Elevation 0–500 m (0–1600 ft) 0–500 m (0–1600 ft)
Distribution
from FNA
AL; AR; FL; GA; IL; IN; KY; LA; MO; MS; NC; OH; SC; TN; TX; VA
[WildflowerSearch map]
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
[WildflowerSearch map]
Discussion

The absence of laminar glands in leaves is a more reliable characteristic for differentiating Triadenum tubulosum from T. walteri than sessile versus petiolate leaves, which are not always quite sessile towards the inflorescence in T. tubulosum, or sepals, which can be obtuse in both.

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

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. 104. FNA vol. 6, p. 103.
Parent taxa Hypericaceae > Triadenum Hypericaceae > Triadenum
Sibling taxa
T. fraseri, T. virginicum, T. walteri
T. fraseri, T. tubulosum, T. walteri
Synonyms Hypericum tubulosum, Elodes drummondii, E. pauciflora, E. tubulosa, H. petiolatum var. tubulosum, H. walteri var. tubulosum, T. longifolium Hypericum virginicum, Elodes campanulata, E. campanulata var. emarginata, E. virginica, Gardenia virginica, Hypericum campanulatum, H. enneandrum, Martia campanulata
Name authority (Walter) Gleason: Phytologia 2: 289. (1947) (Linnaeus) Rafinesque: Fl. Tellur. 3: 79. (1837)
Web links