Hypericum ×mitchellianum
Hypericum chapmanii
Blue Ridge St. John's wort
Apalachicola St. Johnswort
internodes usually 2-lined, sometimes 4-lined or not lined, with black glands scattered on and near lines or all over.
internodes 4-lined at first, soon 4-angled, then terete, not glaucous.
spreading, usually sessile, rarely petiolate (to 0.8 mm);
blade ovate-oblong to oblong or elliptic, 30–42(–52) × 8–22 mm, base subcordate to rounded, margins plane, apex usually rounded, rarely obtuse or subretuse, midrib with 4–5 pairs of branches, tertiary veins densely reticulate toward margins, black glands intramarginal (dense) and laminar (scattered).
blades linear-subulate, 8–25 × 0.5–0.7 mm, not glaucous, base articulated, parallel or slightly expanded, margins revolute, apex acute, midrib unbranched.
corymbiform to broadly pyramidal, (5–)13–61(–124)-flowered, subsidiary branches narrowly ascending or curved-ascending.
shortly cylindric, 1–3-flowered, often with single flowers or triads from 1–2 proximal nodes.
15–20 mm diam.;
sepals not imbricate, erect in fruit, lanceolate to ovate-elliptic or elliptic, subequal, (3–)3.6–4.6(–5.5) × 1–2 mm, apex acute to obtuse;
petals golden yellow, narrowly obovate or oblanceolate to elliptic, 6–11 mm;
stamens (37–)42–56(–62);
anther gland black;
styles 1.5–5 mm.
12–15 mm diam.;
sepals deciduous, not enclosing capsule, 5, linear-subulate, unequal, 5–7 × 0.5 mm, not glaucous;
petals 5, bright yellow, oblong-spatulate, 7–9 mm;
stamens deciduous, 75;
ovary 3-merous;
styles 2.5–4 mm.
ellipsoid to subglobose, 3–7 × 3–4.5 mm, with longitudinal vittae.
narrowly pyramidal-ovoid, 6 × 2.4 mm.
not carinate, 0.7–0.9 mm;
testa not seen.
not carinate, 0.6–0.8 mm;
testa finely foveolate-reticulate.
= 16.
Hypericum ×mitchellianum
Hypericum chapmanii
Hypericum ×mitchellianum is intermediate in all characters between H. graveolens and H. punctatum and, like the latter, produces a ring of 16 chromosomes at meiosis (D. E. Culwell 1970). Culwell has shown that it hybridizes with H. graveolens in the field and that these species can be crossed artificially. He apparently never suspected that H. mitchellianum could itself be a hybrid. Its intermediate morphology and breeding behavior, together with a distribution almost wholly within that of H. graveolens, suggests strongly that H. mitchellianum is the hybrid H. graveolens × punctatum, which apparently arose when the area of H. punctatum extended into that of H. graveolens.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Hypericum chapmanii differs from H. fasciculatum in its taller, single-stemmed habit, thicker stems (to 10–15 cm diameter) with fluted, spongy bark containing large laticifers, and fewer-flowered inflorescences.
Hypericum chapmanii is known from the panhandle of northwestern Florida.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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