Hypericum ascyron subsp. pyramidatum

(Aiton) N. Robson

Bull. Nat. Hist. Mus. London, Bot. 31: 58. 2001.

Common names: Millepertuis à grandes fleurs
Illustrated
Basionym: Hypericum pyramidatum Aiton Hort. Kew. 3: 103. 1789
Synonyms: H. ascyroides Willdenow H. ascyron var. americanum (Spach) Y. Kimura H. bartramium Michaux H. macrocarpum Spach Roscyna americana
Treatment appears in FNA Volume 6. Treatment on page 97.

Herbs erect, branched from base and often with strict, narrowly ascending branches, 5–20 dm. Stems: internodes 4-lined at first, then 4-angled. Leaves spreading, sessile, amplexicaul; blade ovatelanceolate to lanceolate or oblong, 40–85 × 18–37 mm on main-stem, smaller distally and on branches, base rounded to cordate, margins plane, apex usually acute to apiculate, sometimes obtuse, midrib with 4–7 pairs of branches, tertiary-veins densely reticulate toward margins. Inflorescences cylindric to narrowly pyramidal, 1–35-flowered. Flowers: sepals ovate to lanceolate or oblongelliptic, subequal or equal, 8–13 × 4–8 mm, apex acute to acuminate; petals golden yellow, sometimes red-tinged, narrowly obovate to oblanceolate-falcate, 25–40 mm; styles (4–) 5, 3–7 mm. Capsules ovoid, 12–20 (–30) × 10–13 mm. Seeds 1.5 mm, narrowly winged; testa shallowly linear-reticulate.


Phenology: Flowering summer (Jun–Aug).
Habitat: Stream sides, roadside ditches, fens, damp meadows
Elevation: 0–1500 m

Distribution

V6 169-distribution-map.jpg

Ont., Que., Conn., Ill., Ind., Iowa, Kans., Md., Mass., Mich., Minn., Mo., N.Y., Ohio, Pa., Vt., Wis.

Discussion

The American populations of Hypericum ascyron sometimes have been treated as distinct from those of eastern Asia, usually as H. pyramidatum. These populations can be distinguished by the combination of relatively broad leaves, acute sepals, and, usually, almost distinct styles; they are better treated as subsp. pyramidatum (see N. K. B. Robson 2001). The scattered American distribution of Hypericum ascyron, which seems to coincide well with earlier Native American campsites, led W. G. Dore (in herbarium notes) to suggest that it was distributed by aborigines for an as yet unknown reason (see J. M. Gillett and N. K. B. Robson 1981).

Selected References

None.

Lower Taxa

None.
reddish +  and black +
yellow;orange +
oblong;ellipsoid +
acute;acuminate +
Norman K. B. Robson +
(Aiton) N. Robson +
striate +  and smooth +
punctiform +
distinct +  and connate +
rounded +  and cordate +
Hypericum pyramidatum +
4 cm40 mm <br />0.04 m <br /> (8.5 cm85 mm <br />0.085 m <br />) +
ovatelanceolate +  and lanceolate or oblong +
smaller +
1.8 cm18 mm <br />0.018 m <br /> (3.7 cm37 mm <br />0.037 m <br />) +
2 cm20 mm <br />0.02 m <br /> (3 cm30 mm <br />0.03 m <br />) +
1.2 cm12 mm <br />0.012 m <br /> (2 cm20 mm <br />0.02 m <br />) +
1 cm10 mm <br />0.01 m <br /> (1.3 cm13 mm <br />0.013 m <br />) +
Millepertuis à grandes fleurs +
Ont. +, Que. +, Conn. +, Ill. +, Ind. +, Iowa +, Kans. +, Md. +, Mass. +, Mich. +, Minn. +, Mo. +, N.Y. +, Ohio +, Pa. +, Vt. +  and Wis. +
0–1500 m +
connate +  and distinct +
4 cm40 mm <br />0.04 m <br /> (7 cm70 mm <br />0.07 m <br />) +
Stream sides, roadside ditches, fens, damp meadows +
axillary +  and terminal +
cylindric +  and narrowly pyramidal +
persistent +
glandular-ciliate +
(4-)5-merous +
axile +  and parietal +
glanduliferous +
contorted +  and imbricate +
red-tinged +  and golden yellow +
persistent +
distinct +
narrowly obovate;oblanceolate-falcate +
2.5 cm25 mm <br />0.025 m <br /> (4 cm40 mm <br />0.04 m <br />) +
Flowering summer (Jun–Aug). +
Bull. Nat. Hist. Mus. London, Bot. +
carinate +
1.5 cm15 mm <br />0.015 m <br /> (?) +
persistent +
connate +  and distinct +
ovate;lanceolate or oblongelliptic +
subequal +
0.4 cm4 mm <br />0.004 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
Illustrated +
persistent +
connate +  and distinct +
expanded +  and minute +
connate +  and distinct +
spreading;more or less appressed +
elongate +
0.3 cm3 mm <br />0.003 m <br /> (?) +  and 0.7 cm7 mm <br />0.007 m <br /> (?) +
H. ascyroides +, H. ascyron var. americanum +, H. bartramium +, H. macrocarpum +  and Roscyna americana +
Hypericum ascyron subsp. pyramidatum +
Hypericum ascyron +
subspecies +
scalariform +
reticulate +  and foveolate +
hairy +  and glabrous +
6 +, 9 +  and 7 +