Hypericum sphaerocarpum
Hypericum lobocarpum
round-fruit St. John's-wort, roundseed St. Johnswort
five-lobe St. John's-wort
internodes 2–4-lined.
internodes 4-lined at first, soon 2-lined to terete.
blades narrowly elliptic or narrowly oblong to linear, 30–70 × 3–15 mm, base not articulated, narrowly cuneate to linear, margins plane to revolute, apex subacute to rounded, midrib with 0–4 pairs of branches.
blades narrowly oblong to oblanceolate or linear, 35–50 × 3–11 mm, base articulated, narrowly cuneate to attenuate, margins recurved to revolute, apex apiculate-rounded to subacute, midrib with 12–14 pairs of branches.
rounded-corymbiform, 7–70-flowered, narrowly branched, sometimes with dichasia or branches from to 8 proximal nodes.
globose-cylindric to shortly and broadly pyramidal, 5–25-flowered from apical node, with 3–15-flowered dichasia from 1–3 proximal nodes.
10–15 mm diam.;
sepals persistent, not enclosing capsule, 5, broadly ovate to oblong-elliptic, ± unequal, 2.5–5 × 1.5–3 mm;
petals 5, bright yellow, oblanceolate-elliptic to elliptic, 5–9 mm;
stamens persistent, 45–85;
ovary 3-merous, placentation parietal.
10–15 mm diam.;
sepals deciduous, not enclosing capsule, 5, narrowly elliptic to narrowly oblong or oblanceolate-spatulate, subequal to equal, (3.5–)4–4.5 × 0.8–1.5(–2) mm, basal veins 3–7;
petals 5, golden yellow, obovate-oblanceolate, 6–7(–8) mm;
stamens deciduous, 100–150;
ovary (3–)4–5-merous.
broadly ovoid to depressed-globose, 4.5–8 × 4–7 mm.
narrowly ovoid-conic to ovoid, 5.5–7 × 2.5–3.5 mm, notably lobed.
carinate, 2–2.7 mm;
testa coarsely reticulate.
not carinate, 1.2–1.5 mm;
testa linear-reticulate.
= 18.
Hypericum sphaerocarpum
Hypericum lobocarpum
Hypericum sphaerocarpum differs from H. cistifolium and H. nudiflorum in its semiherbaceous habit and more northwestern distribution, as well as in its combination of relatively long, narrow leaves, persistent sepals, globose and apiculate to rounded capsules, and relatively large seeds. The narrow-leaved, bushy form from eastern parts of the range (var. turgidum) merges with the typical form.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Hypericum lobocarpum usually can be distinguished from H. densiflorum by the five-merous ovary; its lobed capsule is a better differentiating characteristic. Hybrid intermediate forms sometimes occur in northwestern Alabama. The South Carolina population (from Allendale County), although well within the area of H. densiflorum and well established, has fruits typical of H. lobocarpum and appears to be either an outlier or an introduction. Hypericum ×dawsonianum Rehder, apparently H. lobocarpum × prolificum and intermediate in form between the presumed parents, is known in cultivation only.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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