2. Triadenum Raf. (marsh St. John’s wort)
Plants perennial
herbs, with rhizomes, glabrous. Young stems or twigs rounded or slightly angled,
not winged. Leaves sessile or short-petiolate, the blades sometimes clasping at
the base. Flowers often relatively few, actinomorphic. Calyces of 5 sepals.
Corollas of 5 petals, these pink, less commonly flesh-colored, not persistent
at fruiting. Stamens 9, in 3 groups of 3, the filaments within a group
noticeably fused toward the base. Staminodes 3, alternating with the groups of
stamens, appearing as ellipsoid, yellow to orange glandular bodies attached at
the base of the ovary. Pistils of 3 fused carpels. Ovary 3-locular, with axile
placentation. Styles 3, free to the base, loosely ascending at flowering, the
stigmas capitate. Fruits capsules, narrowly oblong-ovoid, 2–3 times as long as
the sepals. Seeds numerous, 0.8–1.2 mm long, ovoid-cylindrical, not flattened,
rounded to bluntly pointed at the ends, the surface with a network of fine
ridges and pits, dark brown. Eight to 10 species, eastern U.S. and Canada,
Asia.
Steyermark
(1963) and various other earlier botanists treated Triadenum as a section
within Hypericum, but Gleason (1947) argued persuasively that the odd
staminal characteristics of the species and the petal color warranted the
group’s recognition as a separate genus. Subsequent workers (see Wood and
Adams, 1976) noted differences in vascular patterns of the flowers and corolla
positions in the buds. Thus, most recent authors of floristic manuals (Voss,
1985; Kaul, 1986; Gleason and Cronquist, 1991) have maintained Triadenum
as a separate genus.