Hypericum sphaerocarpum
Hypericum punctatum
round-fruit St. John's-wort, roundseed St. Johnswort
spotted St. John's-wort
internodes 2–4-lined.
clustered, internodes not lined, with black glands scattered all over.
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.
spreading or ascending, usually sessile, rarely petiolate (to 1 mm);
blade elliptic or oblong to lanceolate or triangular-lanceolate, or oblanceolate, 14–40(–58) × 3–17(–22.5) mm, base cordate to narrowly cuneate, margins plane, apex usually rounded to retuse, rarely acute to obtuse, midrib with 3–5 pairs of branches, tertiary veins densely reticulate toward margins, black glands intramarginal (dense) and laminar (scattered).
rounded-corymbiform, 7–70-flowered, narrowly branched, sometimes with dichasia or branches from to 8 proximal nodes.
subcorymbiform to cylindric, 10–206(–600)-flowered, subsidiary branches narrowly ascending to curved-ascending.
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.
8–15 mm diam.;
sepals not imbricate, erect in fruit, lanceolate or oblong-lanceolate to elliptic or ovate-elliptic, subequal, (1.5–)2–4 × 0.8–1.6 mm, apex acute to rounded;
petals pale yellow, oblanceolate to elliptic, 3–6(–9) mm;
stamens (20–)30–60;
anther gland black;
styles 1–4 mm.
broadly ovoid to depressed-globose, 4.5–8 × 4–7 mm.
ovoid to subglobose, 2.5–6 × 2–3.5(–4) mm, with longitudinal vittae or elongate to ovoid vesicles.
carinate, 2–2.7 mm;
testa coarsely reticulate.
not carinate, 0.5–0.7 mm;
testa linear-reticulate.
= 14, 16.
Hypericum sphaerocarpum
Hypericum punctatum
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 punctatum has been confused with H. pseudomaculatum; it can almost always be distinguished by style length and anther gland (black in H. punctatum, amber or pellucid in H. pseudomaculatum). D. E. Culwell’s (1970) record of one specimen of the latter from Missouri with a black anther gland could refer to a hybrid; he and other authors agree that such plants are rare, despite the considerable overlap in distribution of these species. Culwell remarked on the unexpected fecundity of the experimentally produced cross H. graveolens × punctatum but nowhere compared the resulting plants with H. ×mitchellianum, a probable hybrid with that parentage (see discussion
under H. ×mitchellianum. Both H. punctatum and H. ×mitchellianum (but not H. graveolens) display a ring of 16 chromosomes at meiosis, and Culwell suggested that this phenomenon may imply some degree of pseudogamy in the group. C. R. Bell (1965) recorded n = 7 chromosomes for this species; his illustration shows n = 8.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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