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Atlantic St. Peter's-wort, St. Peter's wort

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

Habit Shrubs, usually erect to suberect, rarely decumbent and rooting, usually unbranched, rarely sparsely branched distally, 1–13.5 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 2–4-lined at first, then 2-winged.

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.

Leaf

blades usually oblong to elliptic, rarely obovate to oblanceolate or triangular-ovate, 12–36 × 6–16 mm, base articulated, rounded to slightly cordate-amplexicaul, without glandlike auricles, margins plane to subrecurved, apex rounded to obtuse, midrib with to 3 pairs of branches.

Inflorescences

± narrowly cylindric to narrowly pyramidal, 1–3(–7)-flowered, branching dichasial, from to 4 proximal nodes.

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

20–30 mm diam.;

sepals persistent, enclosing capsule, 4, unequal, outer broadly ovate to circular, 9–20 × 9–18 mm, apex apiculate or obtuse to rounded, inner narrowly elliptic to lanceolate, 7–14 × 2–4 mm, apex acute to subacute;

petals 4, bright yellow, obovate, 11–18 mm;

stamens persistent, 80–100;

ovary 3(–4)-merous.

Capsules

narrowly ellipsoid-ovoid, 7–10 × 5–6.5 mm.

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

Seeds

not carinate, 0.8 mm;

testa shallowly scalariform.

narrowly cylindric to ellipsoid, sometimes carinate;

testa foveolate or reticulate to scalariform [papillose].

x

= 12, 9–7, 6 (dihaploid).

2n

= 18.

Hypericum crux-andreae

Hypericum

Phenology Flowering summer–fall.
Habitat Moist to dry, pine savannas and flatwoods, meadows, bogs, other wet habitats, lake and pond margins
Elevation 0–1500 m (0–4900 ft)
Distribution
from FNA
AL; AR; DC; DE; FL; GA; KY; LA; MD; MS; NC; NJ; NY; OK; PA; SC; TN; TX; VA
[WildflowerSearch map]
[BONAP county map]
from USDA
Nearly worldwide
[BONAP county map]
Discussion

Hypericum crux-andreae, long known as Ascyrum stans, is a derivative of H. frondosum in which the tetramerous tendency in the perianth has become fixed. The low, multistemmed form with cuneate leaves, longer-

pedicellate flowers, and shorter sepals (A. cuneifolium, A. stans var. obovatum) cannot be separated from typical H. crux-andreae.

Linnaeus included “Hypericum ex terra mariana, floribus exiguis luteis” under his phrase name for Ascyrum crux-andreae; that element of the protologue refers to H. mutilum Linnaeus; see N. K. B. Robson (1980).

(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. 85. FNA vol. 6, p. 72. Author: Norman K. B. Robson.
Parent taxa Hypericaceae > Hypericum Hypericaceae
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. 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
Subordinate taxa
H. sect. Myriandra, H. sect. Roscyna, H. sect. Webbia
Synonyms Ascyrum crux-andreae, A. cuneifolium, A. grandiflorum, A. simplex, A. stans var. obovatum, Hypericoides crux-andreae, H. stans Ascyrum, Crookea, Sanidophyllum, Sarothra
Name authority (Linnaeus) Crantz: Inst. Rei Herb. 2: 520. (1766) Linnaeus: Sp. Pl. 2: 783. (1753): Gen. Pl. ed. 5, 341. (1754)
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