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1. Circaea lutetiana L. Map To top
Linnaeus, Sp. pl.: 9 (1753). – Type: Linnaean Herbarium 25.1 (LINN) lectotype, sel. by Boufford, Ann. Missouri Bot. Gard. 69: 879 (1983).
D Dunet Steffensurt. F isovelholehti. N stortrollurt. S stor häxört.
20–50(–80) cm. Rhizome fairly thick, persistent; turions absent or weakly developed (apical winter buds not thicker than the rhizome). Stem erect, terete, moderately to fairly densely hairy from short, recurved hairs, mostly unbranched but often with stunted branches in many leaf axils. Leaves sparsely to moderately hairy from short, curved hairs; petiole 2–8 cm; blade (4–)6–12(–14) × 2–7(–9) cm, with a length/width ratio of 1.4–2.1(–2.8), ovate; base broadly rounded, truncate to slightly cordate; teeth small, distant.
Racemes 15–30(–50)-flowered, elongating before and during anthesis. Bracts absent (except sometimes at the lowermost flowers). Pedicels patent in flower, later deflexed, (4–)6–8 mm (almost full length in flower). Flower disc 0.2–0.4 mm high, protruding. Hypanthium 1–1.5(–2.5) mm. Sepals 2–3.5 × 0.8–2 mm. Petals (1.5–)2–4 × 2–3.5 mm, white to light pink. Stamens with filaments 2.5–4.5 mm, anthers 0.5–0.8 mm. Fruit obovoid to clavate, 3–4 × 1.5–2.5 mm, bilocular; bristles 0.7–1.1 mm long. Seeds (1–)2. – Mid-summer to late summer.
2n=22 (S Sk). – [2n=22]
Distribution. Nem—BNem. – D common in eastern Jylland and in the islands, scattered in NJy and VJy. N rare along the southern coast from Te Kragerø to Ro; scattered in Ho; SF Bremanger and Eid. S common and increasing in much of Sk (especially in the southwest), fairly common in parts of Öl, scattered in coastal Bl, in Hl and southern BhG; Klm Västra Ed, Vg Vänersnäs and Västra Tunhem (formerly also Kinnekulle and scattered in the southwest); introduced in Srm Hölö (established) and Stockholm and in Upl Uppsala.
Boufford (1983) recognized three subspecies: subsp. lutetiana (N, W and C Europe, NW Africa and E Asia), subsp. quadrisulcata (Maxim.) Asch. & Magnus (from C Europe throughout temperate Asia) and subsp. canadensis (L.) Asch. & Magnus (E and C North America).
Habitat. Typically in fairly deep shade on well-drained, preferably base- and nutrient-rich but sparsely vegetated ground. Often in slopes, below cliffs, along roads or rivulets in deciduous woodland (e.g. brook ravines in beech forest or ash- and elmwoods on moist ground), sometimes in tall-herb meadows, in Öl also karst alvar.
Biology. Predominantly outcrossing. Stamens and style do not become functional until the flower has opened, and the anthers are held away from the stigma.
Hybridization. The hybrid of Circaea lutetiana and C. alpina (3) is the sterile C. ×intermedia (2).
2. Circaea ×intermedia Ehrh. Map To top
Ehrhart, Beitr. Naturk. 4: 42 (1789). – Type: Germany, in monte Diester, Ehrhart 101 (GOET) lectotype, sel. by Boufford, Ann. Missouri Bot. Gard. 69: 983 (1983).
D Spidsbladet Steffensurt. F välivelholehti. N mellomtrollurt. S mellanhäxört.
5–50 cm. Rhizome ± filiform, whitish, much branched, dying off in autumn; turions 1–5 cm long, thickened. Stem erect or with ascending base, ± terete (inconspicuously quadrangular as young), glabrous or sparsely hairy, swollen and often bent at nodes, usually branching only in the inflorescence (but often with stunted branches in many leaf axils, basal ones sometimes prolonged into thin runners). Leaves with short, curved hairs at least at the margin and along the veins; petiole 1–4 cm; blade 3–10 × 2–6 cm (length/width ratio 1.4–2.1), ovate; base cordate; teeth few, fairly large, distant.
Racemes 10–20(–40)-flowered, elongating before and during anthesis. Bracts small, setaceous, present at least at some nodes. Pedicels erectopatent or patent in flower, later patent to deflexed, 7–10 mm in fruit. Flower disc variously developed, to 0.2 mm high. Hypanthium 0.5–1.3 mm, shorter than ovary. Sepals 1.5–3.5 × 1–2 mm. Petals (1.2–)2–4 × (0.5–)1.5–3 mm, white to pinkish white. Stamens with filaments (1.5–)2–4 mm, anthers 0.4–0.6 mm. Fruit developing to c. 2(–3) × 1.5 mm (falling before maturity), bilocular but one loculus vestigial; bristles up to 0.5 mm long. Seeds not formed. – Mid-summer to late summer.
2n=22 (N Ho, S Sk). [2n=22, 33]
Distribution. Nem–BNem. – This hybrid has native occurrences also in areas where one or both parents are missing, even far outside the present range of C. lutetiana; also spread with plant material from nurseries. D locally common in eastern Jylland, FyL, Sjæ and Brn; VJy Aaskov, LFM Korselitse Østerskov and Bogø Østerskov. N scattered at Oslofjorden in Øf, Bu and Vf; a few localities in southwestern coastal areas in VA, Ro, Ho, SF and MR. S fairly common in Sk (but mainly on the slopes bordering the lowland), elsewhere rare north to Klm Västra Ed, SmI Barnarp and Huskvarna and Vg Kinnekulle; as a weed in parks and gardens rare north to Vrm Karlskoga, Vsm (Sala 1944) and Dlr Falun.
Mainly in western Europe and northwestern N America; single records from temperate Russia and Japan.
Habitat. In shade on more or less base- and nutrient-rich, usually damp, mull-rich soil, often on slopes with moving subsoil water. Herb-rich woodland (with deciduous trees or spruce), especially on bouldery slopes or along rivulets or springs. Also established as a weed in parks and gardens.
Variation. Specimens from western and southwestern N look more like C. alpina than those from other parts of Norden, often developing the flowers near the top of the inflorescence and having cordate leaf-bases.
Backcrosses to both parents have been reported, e.g. by Lundqvist (1986) and G. Weimarck (1974). These statements may be met with doubts, since C. × intermedia has normally completely sterile seed and pollen (pollen fertility lower than 1%). If more than one hybrid clone is found in the same locality, the situation may be misinterpreted as a case of backcrossing.
Biology. Circaea ×intermedia is the completely seed sterile, vegetatively vigorous hybrid between (1) and (3). Clones propagate most successfully with turions and runners.
Similar taxa. The leaves of Circaea ×intermedia are on average larger and more elongated than those of C. alpina, and more coarsely dentate than in C. lutetiana. In flower it differs from C. lutetiana by presence of bracts, and from C. alpina by its clearly larger flowers. After flowering it is easily recognized by the absence of developing fruits on the elongating inflorescence axis.
3. Circaea alpina L. Map To top
Linnaeus, Sp. pl.: 9 (1753). – Type: Burser Herbarium IX: 24, the right-hand specimen (UPS) lectotype, sel. by Jonsell & Jarvis, Nordic J. Bot. 22: 82 (2002).
D Liden Steffensurt. F pikkuvelholehti. N trollurt. S dvärghäxört.
(5–)10–30 cm. Rhizome filiform, whitish, long and richly branched, dying off in autumn; turions well-developed, tuber-like. Stem erect or with ascending base, angular to subterete, glabrous, swollen at the nodes, mostly unbranched but often with stunted branches in many leaf axils, basal ones often prolonged into thin runners. Leaves with short curved hairs at the margin but otherwise glabrous; petiole 1–3 cm; blade 1.5–5.5(–7) × 1.5–4.5(–5) cm, with a length/width ratio of 1–1.4 (–1.6), broadly ovate, sharply dentate; base deeply cordate; teeth few, large, distant.
Racemes 10–15(–30)-flowered, not elongating until the fruits start ripening. Bracts small, setaceous, present throughout the inflorescence. Pedicels suberect to erectopatent in flower, later patent to deflexed, (1.5–)3–5 mm (still elongating in early fruiting stage). Flower disc low, not protruding from the floral tube. Hypanthium 0.1–0.2(–0.5) mm, much shorter than the ovary, mostly about as wide as long. Sepals 1–2.2 × 0.5–1.2 mm. Petals 0.5–1.5(–2) × 0.5–1.5 mm, white. Stamens with filaments 1–2 mm, anthers 0.2–0.5 mm. Fruit clavate, 2–2.5 × 0.8–1.2 mm, unilocular; bristles up to 0.5 mm long. Seed 1. – Mid-summer to late summer.
2n=22 (S Sk). [2n=22]
Distribution. Nem—MBor[–NBor]. C. 1220 m (N Op Vågå). – Indigenous; rarely grown for ornament. D rare, but locally common in ØJy and Sjæ ***; not known from VJy, SJy or Brn. S rare in Klm and Hl, common inland from northern Sk north to Jmt and Ång, rare in the northernmost provinces; Bl Kyrkhult, Öl Böda and Högsrum. N fairly common in the south and along the western coast north to NNo, Tr, less common in VFi and ØFi. F native and common to fairly common north to PS and PK, rare in KP, Kn, OP, PeP and KiL.
Cold temperate and high mountain areas of Europe, Asia, and N America.
Habitat. Base- and nutrient-rich as well as poorer soils, in swamps and moist deciduous woodland mostly with dense tree-cover.
Variation. Boufford (1983) recognized six subspecies, referring the Nordic material to subsp. alpina.
Biology. Vegetatively propagating with the branching rhizome and runners, often forming dense, mat-like stands.
Hybridization. The hybrid of Circaea alpina and C. lutetiana (1) is the sterile C. x intermedia (2).
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