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millepertuis bor é al, northern bog St. John's-wort, northern St. John's-wort

Habit Herbs annual or perennial, erect, with decumbent to prostrate, rooting base, usually 2–6-branched, branches spreading or ascending distal to middle, 0.9–3.3 dm.
Stems

internodes 4-angled, apical internode shorter than adjacent one or almost absent.

Leaves

spreading, sessile;

blade (concolor), broadly to narrowly oblong or elliptic to oblanceolate or round, 5–15 × 2–5 mm, papery to membranous, margins plane, apex rounded, basal veins 3–5, midrib branched or not.

Inflorescences

cylindric to rounded-pyramidal, 1–13-flowered, branching mostly dichasial;

bracts not linear-subulate.

Flowers

3–5 mm diam.;

sepals usually lanceolate to narrowly oblong, rarely oblanceolate, equal, 2.5 × 0.8–1 mm, margins sometimes ciliate, not setulose-ciliate, apex 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, 4–5 × 2–2.5 mm, usually broadest at or near middle.

Seeds

0.4–0.7 mm;

testa finely linear-scalariform.

2n

= 16 [“18”].

Hypericum boreale

Phenology Flowering summer–early fall (Jul–Sep).
Habitat Bogs, poor fens, lake margins, marshes
Elevation 0–500 m (0–1600 ft)
Distribution
from FNA
CT; DE; IA; IN; MA; MD; ME; MI; MN; NH; NJ; NY; OR; PA; RI; VA; VT; WA; WI; BC; MB; NB; NF; NS; ON; PE; QC; SPM
[BONAP county map]
Discussion

Where Hypericum boreale grows submerged, the plants are almost always sterile with elongated stems and suborbiculate leaves (H. boreale forma callitrichoides Fassett). Such plants intergrade shorewards with typical H. boreale (F. H. Utech and H. H. Iltis 1970). All other chromosome counts for H. mutilum and its near relatives have given n = 8; B. M. Kapoor’s (1972) count of 2n = 18 must be treated with reserve.

Hypericum mutile var. boreale (Britton) E. P. Bicknell is not a validly published name.

The discovery of Hypericum boreale near the mouth of Fraser River at Vancouver in 1989 extends the distribution of this species across Canada almost to the Pacific coast; this occurrence is almost certainly the result of recent introduction.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 6, p. 94.
Parent taxa Hypericaceae > Hypericum > sect. Brathys
Sibling taxa
H. adpressum, H. anagalloides, H. apocynifolium, H. ascyron, H. brachyphyllum, H. buckleyi, H. canadense, H. canariense, H. chapmanii, H. cistifolium, H. concinnum, H. crux-andreae, H. cumulicola, H. densiflorum, H. denticulatum, H. dolabriforme, H. drummondii, H. edisonianum, H. ellipticum, H. erythreae, H. fasciculatum, H. frondosum, H. galioides, H. gentianoides, H. graveolens, H. gymnanthum, H. harperi, H. hypericoides, H. kalmianum, H. lissophloeus, H. lloydii, H. lobocarpum, H. maculatum, H. majus, H. microsepalum, H. mutilum, H. myrtifolium, H. nitidum, H. nudiflorum, H. paucifolium, H. perforatum, H. prolificum, H. pseudomaculatum, H. punctatum, H. radfordiorum, H. scouleri, H. setosum, H. sphaerocarpum, H. suffruticosum, H. tenuifolium, H. tetrapetalum, H. virgatum, H. ×mitchellianum
Synonyms H. canadense var. boreale, H. mutilum subsp. boreale, Sarothra borealis
Name authority (Britton) E. P. Bicknell: Bull. Torrey Bot. Club 22: 213. (1895)
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