Flora of North America species comparison

The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Hypericum perforatum

Hypericum microsepalum

Chase-devil, common St. John's-wort, Klamath weed, millepertuis commun, Tipton's weed

flatwoods St. Johnswort
Habit Shrubs, erect to ascending, bushy, with ± numerous, sometimes straggling branches, 1.5–7 dm.
Stems

internodes 4-lined at first, eventually 2-lined.
Leaf

blades narrowly oblong or oblanceolate to linear, 5–15 × 1–3 mm, base not articulated, rounded to cuneate, margins recurved to subrevolute, apex rounded to obtuse, midrib with 1–3 pairs of branches.
Inflorescences

rounded-pyramidal, 1–3-flowered, narrowly branched, sometimes with 1–3-flowered dichasia or branches from to 4 proximal nodes.
Flowers

15–25 mm diam.;

sepals persistent, not enclosing capsule, (3–)4(–5), oblong or elliptic-oblong to linear, subequal or equal, 3–5 × 1–1.4 mm;

petals (3–)4(–5), bright yellow, obovate (larger pair) to obovate-oblong (smaller pair), 10–12 mm;

stamens persistent, 60–70;

ovary 3-merous, placentation parietal.
Capsules

cylindric-ellipsoid to narrowly ovoid-conic, 6–8 × 2.5 mm.
Seeds

not carinate, 0.9–1 mm;

testa linear-foveolate.
2n

= 18.

Hypericum perforatum

Hypericum microsepalum
Phenology Flowering late winter–spring (Feb–May), late fall (Nov).
Habitat Low, pine flatwoods, moist to wet, on sand
Elevation 0–100 m [0–300 ft]
Distribution
from FNA
AR; CA; CO; CT; DC; DE; IA; ID; IL; IN; KS; KY; MA; MD; ME; MI; MN; MO; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; VA; VT; WA; WI; WV; WY; BC; MB; NB; NF; NS; ON; PE; QC; Europe; Asia (sw Arabia, China, India, Mongolia, Siberia); n Africa [Also introduced widely elsewhere]
[WildflowerSearch map]
[BONAP county map]
from FNA
FL; GA
[WildflowerSearch map]
[BONAP county map]
Discussion

Subspecies 4 (1 in the flora).

Hypericum perforatum has been introduced into various parts of the world, including North America, where only subsp. perforatum is represented. The range of variation in the flora area is less than occurs in Europe, and signs of hybridization that are common there are absent in North America.

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

Hypericum microsepalum is related to H. cistifolium, not to the other four-petaled species attributed to Ascyrum, and can be distinguished from it by the bushier habit and smaller leaves and by the usually four-merous flowers with larger petals.

Hypericum isophyllum Steudel is an illegitimate name for H. microsepalum.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 6, p. 99. Treatment author: Norman K. B. Robson. FNA vol. 6, p. 83. Treatment author: Norman K. B. Robson.
Parent taxa Hypericaceae > Hypericum > sect. Hypericum Hypericaceae > Hypericum > sect. Myriandra
Sibling taxa
H. adpressum, H. anagalloides, H. apocynifolium, H. ascyron, H. boreale, 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. prolificum, H. pseudomaculatum, H. punctatum, H. radfordiorum, H. scouleri, H. setosum, H. sphaerocarpum, H. suffruticosum, H. tenuifolium, H. tetrapetalum, H. virgatum, H. ×mitchellianum
H. adpressum, H. anagalloides, H. apocynifolium, H. ascyron, H. boreale, 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. 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
Subordinate taxa
H. perforatum subsp. perforatum
Synonyms Ascyrum microsepalum, Crookea microsepala, Isophyllum drummondii
Name authority Linnaeus: Sp. Pl. 2: 785. (1753) (Torrey & A. Gray) A. Gray ex S. Watson: Smithsonian Misc. Collect. 258: 456. (1878)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



Type/paste one or more Latin names into the boxes above; matching taxa will show up below the box as you type. You can use the up/down arrow keys to move through the list.

(If the plant you're looking for doesn't show up in the auto-complete list, that means it either isn't described in Flora of North America yet, or it's listed under a synonym. And please note that Flora of North America is still missing several plant families, including Apiaceae, Boraginaceae, and Polemoniaceae.)

The species comparison tool is brought to you by:
Northwest Wildflowers