Hypericum lobocarpum Gatt. ex J.M. Coult.

Fivelobe St. John's Wort

Hypericum_lobocarpum_plant.jpg
STATS

Native
CC = 9
CW = 5
MOC = 4
SRank = S1

© SRTurner

Family - Hypericaceae

Habit - Shrubs to 1.5 m tall, sometimes woody only toward the base.

Stems - Erect or ascending, sometimes arching. Bark reddish brown, smooth, usually peeling in thin strips. Twigs angled or slightly ridged below each leaf, reddish brown, the older stems usually rounded but often with longitudinal lines below the leaves.

Hypericum_lobocarpum_stem1.jpg Young stem and nodes.

© SRTurner

Hypericum_lobocarpum_stem2.jpg Older stem.

© SRTurner

Leaves - Opposite, simple, jointed at the base. Blades 15-50 mm long, 3-12 mm wide, narrowly oblong to oblanceolate or less commonly linear, rounded to bluntly pointed at the tip and often with a minute, sharp point, tapered or narrowed to a petiole-like base, the margins rolled under at maturity, herbaceous to somewhat leathery in texture, with 1 main vein sometimes faintly visible, the surfaces lacking noticeable black dots, lines, or streaks but usually with minute, faint, pale (pellucid) dots visible via transmitted light, the upper surface green, the undersurface pale green and often somewhat glaucous.

Hypericum_lobocarpum_leaves.jpg Stem and leaves.

© SRTurner

Hypericum_lobocarpum_leaf1.jpg Leaf adaxial.

© SRTurner

Hypericum_lobocarpum_leaf2.jpg Leaf abaxial.

© SRTurner

Hypericum_lobocarpum_pellucid.jpg Leaf with transmitted light, showing pellucid dots.

© SRTurner

Inflorescences - Clusters of mostly 3-17 flowers, at the branch tips and from the axils of the uppermost leaves, appearing paniculate.

Hypericum_lobocarpum_inflorescence1.jpg Inflorescence.

© SRTurner

Flowers - Actinomorphic. Sepals 5, all similar in size and shape, 3.5-4.5 mm long, not becoming enlarged at fruiting, narrowly elliptic to narrowly oblong-oblanceolate, the margins often somewhat curled, lacking noticeable yellowish brown or black dots, lines, or streaks. Petals 5, 6-8 mm long, oblanceolate to obovate, yellow to orangish yellow, usually shed before fruiting. Stamens 100-150, the filaments not fused into groups. Ovary incompletely mostly 4-or 5-locular, the placentation more or less axile. Styles mostly 4 or 5 (some 3-styled flowers present in Missouri material), free above the base, but erect and more or less appressed at flowering, persistent and usually separating somewhat as the fruit matures, the stigmas minute.

Hypericum_lobocarpum_flower1.jpg Flower.

© SRTurner

Hypericum_lobocarpum_sepals.jpg Sepals (and bracteal leaves)

© SRTurner

Hypericum_lobocarpum_carpel1.jpg Carpel showing distinct lobing.

© SRTurner

Hypericum_lobocarpum_carpel2.jpg Top view of lobed carpel, with 4 locules evident.

© SRTurner

Fruits - Capsules 5-7 mm long, narrowly ovoid or somewhat conical, widest below the midpoint, tapered to the beak(s), noticeably lobed longitudinally and appearing mostly 4-or 5-lobed in cross-section. Seeds numerous, 1.2-1.5 mm long, the surface with fine longitudinal lines, these sometimes forming a faint network, dark brown to nearly black.

Hypericum_lobocarpum_fruits.jpg Fruits.

© SRTurner

Flowering - June - September.

Habitat - Sandy forest openings, fens.

Origin - Native to the U.S.

Lookalikes - Strongly resembles Hypericum prolificum, which is much more common.

Other info. - This attractive plant was thought to be extirpated from Missouri, and in fact Vol. 2 of Yatskievych's Flora of Missouri states that it is known in the state only from historical records. However, in June 2006, following some detective work by Tim Smith of MDC, the species was re-discovered in a few far southern Missouri counties (Missouriensis 2007, 27, 1.) It is uncommon in the state, with its main range comprising Arkansas and Louisiana and abutting portions of adjacent states. The photos above were taken at a location less than 200 feet north of the Arkansas border. The plant is easily confused with the far more common H. prolificum, with the main differentiating factor being 4-5 locules in the ovary, as evidenced by strongly longitudinally lobed carpels and capsules. In contract, H. prolificum ovaries usually contain 3 locules and are not lobed. The fruits of H. lobocarpum are also smaller (5-7 mm) than those of H. prolificum (7-14 mm).

Photographs taken at Big Cane Conservation Area, Butler County, MO, 6-9-2023 and 8-19-2024 (SRTurner).