Flora of North America species comparison

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Triadenum tubulosum

lesser marsh St. Johnswort
Habit Herbs erect, to 10 dm, sometimes branching from near base, sometimes with ascending branches in distal 1/2+.
Stems

internodes 2-lined 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.
Inflorescences

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

cylindric, 8–12 × 3.5–4 mm, apex obtuse.
Seeds

0.8–1.2 mm.

Triadenum tubulosum
Phenology Flowering late summer–early fall (Aug–Sep).
Habitat Swampy or marshy ground in woods
Elevation 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]
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.)
Source FNA vol. 6, p. 104.
Parent taxa Hypericaceae > Triadenum
Sibling taxa
T. fraseri, T. virginicum, T. walteri
Synonyms Hypericum tubulosum, Elodes drummondii, E. pauciflora, E. tubulosa, H. petiolatum var. tubulosum, H. walteri var. tubulosum, T. longifolium
Name authority (Walter) Gleason: Phytologia 2: 289. (1947)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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