Hypericum mutilum

Linnaeus

Sp. Pl. 2: 787. 1753.

Common names: Dwarf St. John’s wort
Synonyms: Sarothra mutila (Linnaeus) Y. Kimura
Treatment appears in FNA Volume 6. Treatment on page 93. Mentioned on page 86, 89, 92, 94.
Revision as of 18:46, 18 September 2019 by FNA>Volume Importer

Herbs annual or perennial, usually erect, sometimes decumbent and rooting, basal branches sometimes present, usually with to 10 pairs of spreading branches distal to middle, 0.5–8 dm. Stems: internodes 4-angled. Leaves spreading, sessile or amplexicaul; blade paler abaxially, ovate, elliptic, or elliptic-oblong (proximal), ovate or suborbiculate to elliptic or lanceolate (mid and distal), 3–27(–40) × 1–15 mm, papery to membranous, margins plane, apex obtuse to rounded, basal veins 3–5, midrib with to 3 pairs of branches. Inflorescences cylindric, 5–60-flowered, branching mostly dichasial; bracts linear-subulate. Flowers 3–5 mm diam.; sepals lanceolate to linear-lanceolate or elliptic-oblong to oblanceolate, equal or unequal, 2–4.5 × 0.6–1.5 mm, margins sometimes ciliate, not setulose-ciliate, apex usually acute to apiculate, sometimes obtuse to rounded; petals pale yellow, oblong, 1.7–3.5 mm; stamens 5–16, scarcely grouped; styles 0.5 mm; stigmas broadly capitate. Capsules narrowly ovoid to cylindric-ellipsoid, 2–5 × 1.6–2.4 mm, usually broadest at or near middle. Seeds 0.4–0.7 mm; testa finely linear-scalariform.

Distribution

V6 158-distribution-map.jpg

c, e North America, introduced in w North America.

Discussion

Subspecies 2 (2 in the flora).

Selected References

None.

Key

1 Stems: apical internode shorter than adjacent one or almost absent; inflorescences: branching mostly dichasial from 2–10 nodes. Hypericum mutilum subsp. mutilum
1 Stems: apical internode usually longer than adjacent one; inflorescences: branching from 1–4(–6) nodes, branches diffuse and repeatedly monochasial distally. Hypericum mutilum subsp. latisepalum