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millepertuis à grandes fleurs

millepertuis, St. Andrew's cross, St. John's-wort

Habit Herbs erect, branched from base and often with strict, narrowly ascending branches, 5–20 dm. Herbs, annual or perennial, subshrubs, or shrubs [trees], sometimes rhizomatous, glabrous or hairy, with glandular canals, lacunae, or dots containing resins or waxes (amber), essential oils (pale, translucent), and/or, sometimes, hypericin and pseudohypericin (black or red) in various parts.
Stems

internodes 4-lined at first, then 4-angled.

internodes terete (not lined) or 2-, 4-, or 6-lined at first (lines usually raised), then sometimes becoming angled, terete, or winged;

bark smooth or striate, sometimes corky, punctiform.

Leaves

spreading, sessile, amplexicaul;

blade ovate-lanceolate 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.

terminal, cymose, 2+-flowered, or flowers solitary, branching stellate [cupulate];

sepals persistent or deciduous, (3–)4–5, distinct or ± connate, margins sometimes glandular-ciliate;

petals persistent or deciduous, (3–)4–5[–6], contorted, yellow to orange, sometimes red-tinged;

stamens persistent or deciduous, (5–)10–300(–650), in continuous or interrupted ring or in (3–)4–5 fascicles, fascicles distinct or connate, each with 1–60+ stamens;

filaments distinct or basally connate;

anthers yellow to orange, oblong to ellipsoid, almost isodiametric, sometimes with amber or black gland on connective;

staminode fascicles 0 [3];

ovary 2–5-merous;

placentation axile to parietal;

ovules 2+ on each placenta;

styles distinct or ± connate basally, spreading to ± appressed.

Flowers

sepals ovate to lanceolate or oblong-elliptic, 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.

2–5-valved, sometimes with glandular vittae or vesicles.

Seeds

1.5 mm, narrowly winged;

testa shallowly linear-reticulate.

narrowly cylindric to ellipsoid, sometimes carinate;

testa foveolate or reticulate to scalariform [papillose].

x

= 12, 9–7, 6 (dihaploid).

Hypericum ascyron subsp. pyramidatum

Hypericum

Phenology Flowering summer (Jun–Aug).
Habitat Stream sides, roadside ditches, fens, damp meadows
Elevation 0–1500 m (0–4900 ft)
Distribution
from FNA
CT; IA; IL; IN; KS; MA; MD; MI; MN; MO; NY; OH; PA; VT; WI; ON; QC
from USDA
Nearly worldwide
[BONAP county map]
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).

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

Species ca. 490 (54 in the flora).

Shrubs with deciduous leaves, petals, and stamens belong to either Hypericum sect. Ascyreia Choisy (with five stamen fascicles and five styles) or sect. Androsaemum (Duhamel) Godron (with five stamen fascicles and three or four styles). These are all introductions, mostly garden escapes. Those in sect. Ascyreia include: Hypericum calycinum Linnaeus, a low shrub with creeping stolons and flowers 50–95 mm diam. that has been found in California, Oregon, and Washington; H. ×moserianum Luquet ex André, its hybrid with H. patulum Thunberg, a low (sterile?) branching shrub with red anthers; and H. hookerianum Wight & Arnott, a shrub to 2 m tall with narrow leaves and a dense ring of relatively short stamens, recorded from California (its identity requires confirmation). In sect. Androsaemum, H. androsaemum is a deciduous shrub with relatively small flowers and baccate fruits that ripen from cherry-red to black; it has been found in British Columbia and in California and Washington.

Introduced herbaceous species with three stamen fascicles and three styles include: Hypericum hirsutum, with hairy stems and leaves (Ontario); H. tetrapterum, with four-winged internodes and lanceolate sepals (British Columbia and Washington); H. pulchrum with cordate leaves and red-tinged petals (Newfoundland, St. Pierre and Miquelon); and H. humifusum Linnaeus, a procumbent herb with unequal sepals (British Columbia).

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

Key
1. Herbs, subshrubs, or shrubs, black glands absent; stamens in continuous or interrupted ring or in 4 or 5 barely discernable fascicles, each of 1 or 2 stamens
→ 2
1. Herbs or shrubs, black and/or red glands usually present throughout, sometimes absent; stamens in 5 fascicles, each of 2+ stamens
→ 3
2. Herbs (perennial), subshrubs, or shrubs; petals deciduous; stamens usually persistent, sometimes deciduous, 30–650, in continuous ring or in 4–5 barely discernable fascicles; styles ± appressed, bases distinct.
sect. Myriandra
2. Herbs (annual or perennial); petals persistent; stamens persistent, (5–)10–80, usually in continuous or interrupted ring, sometimes in 5 barely discernable fascicles; styles ± spreading, bases distinct.
Hypericum informal sect. group Brathys
3. Shrubs; leaves deciduous (base articulated); style bases distinct.
sect. Webbia
3. Herbs (perennial); leaves persistent or tardily deciduous (base not articulated) or; style bases ± connate or distinct
→ 4
4. Herbs, black glands absent; flowers 40–70 mm diam.; stamens 150, in 5 fascicles, fascicles usually distinct, rarely 1 pair connate; styles ± appressed, bases ± connate or distinct.
sect. Roscyna
4. Herbs, black glands usually on leaves, sepals, and petals and, sometimes, on stems and anthers; flowers 6–35 mm diam.; stamens 20–109, in 5 fascicles, fascicles connate (as 2 + 2 + 1); styles spreading, bases distinct.
Hypericum informal sect. group Hypericum
Source FNA vol. 6, p. 97. FNA vol. 6, p. 72. Author: Norman K. B. Robson.
Parent taxa Hypericaceae > Hypericum > sect. Roscyna > Hypericum ascyron Hypericaceae
Subordinate taxa
H. sect. Myriandra, H. sect. Roscyna, H. sect. Webbia
Synonyms H. pyramidatum, H. ascyroides, H. ascyron var. americanum, H. bartramium, H. macrocarpum, Roscyna americana Ascyrum, Crookea, Sanidophyllum, Sarothra
Name authority (Aiton) N. Robson: Bull. Nat. Hist. Mus. London, Bot. 31: 58. (2001) Linnaeus: Sp. Pl. 2: 783. (1753): Gen. Pl. ed. 5, 341. (1754)
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