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Peucedanum L.

Linnaeus, Sp. pl.: 245 (1753).
Imperatoria L. (1753).
Oreoselinum Hill (1753).
Thysselinum Hoffm. (1814).
Hemicryptophytes. Glabrous, biennial or perennial herbs with tap­root or rhizome. Stem terete to sulcate, hollow or solid. Leaves 2–4-pinnate or 1–2-ternate. Bracts present or absent. Flowers not or slightly zygomorphic; sepals narrow (sometimes indistinct); petals white to light pink, emarginate to bifid. Fruit ± dorsiventrally flattened; carpophore filiform, divided to the base. Mericarps with 3 central, in cross section low to indistinct ridges, and two wide lateral wings; stylopodium conical to slightly flattened, 0.6–1.2 mm wide; style 0.7–1.7 mm, directed outwards.
Chromosome base-number x=11.
Taxonomy. Peucedanum is a large and heterogeneous genus distributed in Europe, Asia, Africa and North America, and so far only partly revised (cf. Pimenov & Leonov 1993). Recently, some of the European species have been divided into several small genera, based on cladistic analyses of molecular data (Spalik et al. 2004), and of characters of i.a. seedlings, stomata, pollen and chemical substances (cf. Reduron 2008). However, such a division still seems premature, since data are lacking for several other segregates of Peucedanum. Furthermore, some of the segregate genera are located in the same clade as Peucedanum s.str. (i.a. the Nordic species P. ostruthium, P. oreoselinum and P. palustre, referred to Imperatoria, Oreoselinum and Thysselinum respectively; cf. Spalik et al. 2004), and could be treated as one monophyletic genus without any contradiction to the molecular data.
1 Leaves 1–2-ternate; terminal ultimate leaflets wider than 7 cm 3. P. ostruthium
- Leaves 2–4-pinnate; terminal ultimate leaflets narrower than 6 cm 2
2 Stem solid; angle primary leaflet/rachis 75° or wider 2. P. oreoselinum
- Stem hollow; angle primary leaflet/rachis narrower than 70° 1. P. palustre

1. Peucedanum palustre (L.) Moench         map         ill.

Moench, Methodus: 82 (1794). – Selinum palustre L., Sp. pl.: 244 (1753). – Thysselinum palustre (L.) Hoffm. (1814). – Type: Ill. in Bauhin, Prodr. Theatri Bot., 85, 85 (1620) lectotype, sel. by Reduron et al., J. Bot. Soc. Bot. France 1: 96 (1997).

D Kær-Svovlrod. F suoputki. N mjølkerot. S kärrsilja.

Biennial, to 120 cm; tap­root with an aromatic scent, (3.5–)5–13 mm thick, with usually swollen, 1–5 mm thick lateral branches. Stem hollow; basal part 2–7 mm thick, angular to sulcate, distinctly purplish, not glaucous, and with some remains of dead leaves; upper internodes sometimes indistinctly winged. Leaves 1–5 at the base and 2–5 on the stem, the lowest stem leaf or the innermost basal one the largest; sheath narrow, sometimes purple-tinged; petiole (7–)13–25(–33) cm; blade 2–4-pinnate, 7–22(–33) × (4–)7–13(–22) cm (length/width ratio 1–2.1). Primary leaflets 4–7 pairs, without stipels at the insertions; angle leaflet/rachis 30–50(–70)°; longest petiolules 0.7–3.4(–5.7) cm. Ultimate leaflets 2–3-pinnatifid, with 3–5 pairs of lobes; petiolule 4–17(–31) mm; blade 15–46(–70) × 9–35(–56) mm (length/width ratio (0.9–)1.2–2.2); base shortly attenuate to cordate. Ultimate lobes (3.9–)7–14(–29) × 0.9–2.9 mm, with a length/width ratio of 2.6–10(–18); apices acute or sometimes acuminate, with purplish or rarely white tips.
Umbels usually slightly convex, 3–4.5 cm high and 7–14 cm wide; peduncle (4.5–)7–17 cm; rays straight, 3–6 cm, distinctly papillose on the adaxial side. Bracts 4–12, persistent, 7–38 × 0.8–4 mm, distinctly membrane-bordered. Umbellules 13–33; pedicels 0.6–1.5 cm, distinctly or indistinctly papillose on the adaxial side. Bractlets 7–13, persistent, (3–)6–23 × 0.7–1.5 mm, ± distinctly membrane-bordered. Flowers 21–42 per umbellule; sepals 0.2–0.5 mm; petals white to pale pink, 1.2–1.4 × 1–1.2, emarginate (apical cut 0.1–0.3 mm deep); filaments 1.5–1.7 mm; anthers 0.35–0.6 mm. Fruits broadly elliptic in outline, slightly dorsiventrally flattened, straw-coloured to dark brown. Mericarps 2.8–5.2 × 1.9–4.4 × 0.4–0.5 mm (length/width ratio 1.2–1.6); wings 0.2–0.8 mm wide; dorsal valleculae narrow, each with 1 dark brown vitta; pericarp consisting of cells with wide cavities. – Mid-summer to late summer.
2n=22 (F V, N Vf, S Bl, Sk). [2n=22]
Distribution. Nem–MBor(–NBor). Alt. N He 550 m. – fairly common throughout. N scattered to rather common in the southeast, reaching He Trysil, Op Nord-Fron and Bu Krødsherad; rarer along the western coast north to Ho Bergen; rare in SF. common north to central Vrm, central Dlr, Mpd and coastal Ång, scattered in northern Vrm, northern Dlr and eastern Jmt; further north rare inland to PL Arvidsjaur and scattered to rare along the coast to northern Nb. ± common to central PeP and central Ks, rare in KiL and SoL. – No vouchers seen from S LL, F EnL or InL.
Europe except the NW and S parts, W Siberia.

Habitat. On damp or wet mull-rich or peaty soil, rather shady or in full sun, with a wide amplitude as to pH and nutrients: poor and rich fen (a character species in fen borders of peatland and lakelets), wet deciduous woodland, sea- and freshwater shores; also in strongly man-influenced places such as ditches and mesic to moist hay-meadows; tolerant to grazing.

Biology. Dead shoots do not persist to the next year (cf. Selinum carvifolia). The fruits can float due to air-filled cells in the pericarp, and they are probably mainly spread with water (cf. Thellung 1926).

Variation. Peucedanum palustre is very variable in leaf shape and shape of leaf-lobes, but no geographical trends or correlation with other morphological characters have been found.

Similar taxa. Peucedanum palustre is very similar to Selinum carvifolia (see that species) and Peucedanum oreoselinum (which has usually relatively wider ultimate leaflets, and grows in dry sites; see also the key). It may also be confused with Oenanthe aquatica (which is distinguished by short-stalked umbels opposite the supporting leaf of the continuing lateral shoot, flowers with distinct sepals and a leaflet/rachis angle of about 90°) or Bunium bulbocastanum (see that species).

2. Peucedanum oreoselinum (L.) Moench         map         ill.

Moench, Methodus: 82 (1794). – Athamanta oreoselinum L., Sp. pl.: 244 (1753). Oreoselinum nigrum Delarbre (1800). – Type: Linnaean Herbarium 345.6 (LINN) lectotype, sel. by Jarvis & Knees, Taxon 37: 475 (1988).

D Bakke-Svovlrod. N bakkekjeks. S backsilja.
Perennial, to 80 cm, similarly scented as Petroselinum crispum; tap­root 3.5–11 mm thick, not branched. Stem solid; basal part 2–7 mm thick, terete to angular or occasionally sulcate, usually not purplish, more or less glaucous, and with remains of dead leaves. Leaves 1–5 at the base and (0–)3–5 on the stem, the outermost basal usually the largest one; sheath rather broad, ± purplish; petiole 7–34 cm; blade 2–4-pinnate, 7–15(–25) × 9–22 cm (length/width ratio 0.6–1.1). Primary leaflets usually with stipels, 3–7 pairs; angle leaflet/rachis 75–120°; longest petiolules 1.4–5.7 cm. Ultimate leaflets 2–3-pinnatifid, with 2–5 pairs of lobes; petiolule 3.5–17 mm; blade 7–31 × 11–33(–50) mm (length/width ratio 0.6–1.1); base truncate to cordate. Ultimate lobes 1.7–5(–9.2) × 0.9–3.3 mm, with a length/width ratio of 1.2–2.9(–4.2); apices acute to acuminate, with white or sometimes slightly purplish tips.
Umbels flat to slightly convex, 4.5–6 cm high and 11–16 cm wide; peduncle 10–26 cm; rays straight or bent inwards, 4.5–9.5 cm, not or indistinctly papillose on the adaxial side (with smaller papillae than in P. palustre). Bracts 5–14, persistent, 7–15 × 0.7–1.7 mm, indistinctly membrane-bordered. Umbellules 19–33; pedicels 0.7–1.5 cm, glabrous or indistinctly papillose on the adaxial side. Bractlets 6–12, persistent, 5–9 × 0.4–0.9 mm, not or indistinctly membrane-bordered. Flowers 28–37 per umbellule; sepals 0.2–0.5 mm; petals white, occasionally slightly pink in bud, 1.1–1.3 × 1–1.3, emarginate (apical cut 0.2–0.5 mm deep); filaments 1.5–1.7 mm; anthers 0.5–0.9 mm. Fruits almost orbicular in outline, distinctly dorsiventrally flattened, straw-coloured. Mericarps 3.1–5.5 × 2.4–5.2 × 0.3–0.4 mm (length/width ratio 1–1.3); wings 0.5–1.1 mm wide; valleculae wide, each with 1 brown to dark brown vitta. – Mid-summer.
2n=22 (S Sk 2). [2n=22]
Distribution. Nem. – D regarded as indigenous in Brn (several localities, extant only in Rønne, Klemensker and Rø); probably apophytic in LFM Møn (Ulfshale) 1911–21. S Sk regarded as indigenous, perhaps declining: widespread in the southeast, also near the south coast (few localities left), and Färlöv, Vinslöv and Åhus in the northeast (isolated secondary occurrences, e.g. railway); Bl probably apophytic in Nättraby (Skillinge, sandy roadside, known since 1920); Öl fairly rare in the central part, regarded as indigenous.
Outside Norden in C, E and S Europe.

Habitat. On rather dry, ± calcareous, sandy or gravelly soil in full sun, often in slopes with a vegetation that is not closed (Sterner 1922); primarily in steppe-like dry meadow, secondarily in roadsides, railway embankments, abandoned fields  and gravel pits.

Similar taxa. Peucedanum oreoselinum is characterized by the repeatedly patent leaflets; P. palustre (1) and Selinum carvifolia have narrower angles (further differences under each of them).

3. Peucedanum ostruthium (L.) W.D.J. Koch      map      ill.

Koch, Gen. pl. umbell.: 95 (1824). – Imperatoria ostruthium L., Sp. pl.: 259 (1753). – Type: Clifford Herbarium 103, Imperatoria 1 (BM) lectotype, sel. by Reduron & Jarvis, Regnum Veg. 127: 57 (1993).

D Mesterrod. N mesterrot. S mästerrot.
Literature. Svedjemyr 1989.
Perennial, to 80 cm; rhizome creeping, 6–18 mm thick, with a scent reminiscent of Acorus calamus. Stem hollow; basal part 5.5–9 mm thick, terete, slightly purplish, not glaucous. Leaves mainly basal, ± funnel-shaped with erect petioles (stem leaves 2–4, smaller); sheath broad, inflated (especially on upper leaves), usually not purplish; petiole 17–45 cm; blade 1(–2)-ternate, 9–20 x 15–30 cm (length/width ratio 0.5–0.8); margin with acute to acuminate  teeth having white or purplish tips. Primary leaflets with shortly attenuate to cordate base (oblique in lateral leaflets); lobes broadly acuminate to almost rounded. Apical leaflet usually 1-pinnatifid (lobed in lower part and doubly serrate in upper part) with 3–5 pairs of lobes/main teeth, with the proximal sinus frequently reaching the midvein; petiolule 2–6.8 mm; blade 6.7–13.5 x (7.2–)9.2–15 cm (length/width ratio 0.7–1). Apical leaflet of 2-ternate leaves usually petiolulate, with cuneate base.
Umbels flat to slightly convex, 4–5 cm high and 11–17 cm wide; peduncle 7–14 cm; rays straight or bent inwards, 5.5–8 cm, not or indistinctly papillose on the adaxial side (papillae smaller than in P. palustre). Bracts 2–13, usually falling off at anthesis. Umbellules (19–)35–54; pedicels 1.1–1.6 cm, not or indistinctly papillose on the adaxial side. Bractlets (2–)4–10, almost always persistent, 4–10 × 0.1–0.2 mm, not membrane-bordered. Flowers (29–)37–63 per umbellule; sepals 0.1–0.3 mm; petals white, occasionally slightly pink, 1.3–1.6 × 1–1.2, emarginate (apical cut 0.3–0.4 mm deep); filaments 1.8–2.5 mm; anthers 0.4–0.5 mm. Fruits almost orbicular in outline, distinctly dorsiventrally flattened, straw-coloured. Mericarps 3.3–6.1 × 2.6–5.6 × 0.4 mm (length/width ratio 1–1.2); wings 0.6–1.4 mm wide; valleculae wide, each with 1 brown to dark brown vitta. – Mid-summer.
Distribution. (Nem–)BNem–MBor. Alt. N ST 520 m. – Cultivated already in the Medieval at least in D and S Sk, but probably not widely spread until much later; often becoming well established, but rarely seen far from where it was once planted. – VJy 8 localities (latest record Almstok 2001), ØJy c. 5 localities (latest record Pindstrup 2001), Vigerslev 1876–1904, Morud 1893, and Brn Almindingen 1950, 1979 (also known from Svaneke 19th century, Bodilsker 1850–66); extinct in NJy (latest Hobro c. 1870) and FyL. N rare at Oslofjorden (Øf Halden and Ak Aurskog-Høland and Oslo 1921) and at the western coast from VA Åseral to ST Trondheim (Melhus); established in Ho the surroundings of Bergen. S north of Sk a resident to central Dlr, mostly scattered to fairly common inland, but rare in Bl (Jämshög known since 1890), Klm (c. 20 localities), eastern SmI, northern Vg, Vrm except the southeastern part, and Srm (c. 10 localities); casual in Sk (Malmö 1867, Hammenhög 1999 and Vittsjö 2003), Gtl (5 records, latest in Fide 1936), Upl (c. 10 localities), Hls (Hanebo 1989, Norrbo 1880), Hrj (Lillhärdal 1988), Vb (Umeå 1998), Nb (7 localities in the 1990’s).
 Grown as a medicinal plant already in ancient time; native to mountains of C and S Europe. Reported as introduced in North America.
Habitat. Mesic to rather dry soil, in full sun to half shade. Reported from mesic meadow and mountain pasture (Dlr), edges of deciduous woodland, shady river-slopes and roadsides (Hl, Vg) and a railway embankment (Dlr), but usually near farms and abandonded crofts (exclusively so e.g. in SmI and Klm).
Biology. Flowering is rare in Peucedanum ostruthium and seeds are usually not viable (Svedjemyr 1989, Malmgren 1982). Although it might have been spread with seed to some localities, e.g. in Dlr Ludvika (railway slope), the species is probably more frequently spread with rhizome fragments. It reproduces locally by vigorous rhizome growth, producing clones of several square meters. A clone can persist in a locality for at least 170 years (Bertilsson et al. 2002). – Avoided by grazers.

Similar taxa. Peucedanum ostruthium with its ternate, broadly lobed leaves and ± caducous bracts is strikingly different from the other two species in the genus, and very characteristic in the field, the leaf-blades forming wide funnels. It can be mistaken for a stout Aegopodium podagraria, but the latter differs by narrower leaflets with serrate to indistinctly doubly serrate margin, and lacks bracts and bractlets. In Angelica archangelica and A. sylvestris the leaves are usually larger, twice pinnate and serrate to indistinctly doubly serrate; A. archangelica also differs by yellow-green flowers assembled in globose umbels, and A. sylvestris by more densely papillose rays, with longer papillae.

References To top

Bertilsson, A., Aronsson, L.-E., Bohlin, A., Börjeson, G., Geijer, M., Ivarsson, R., Janson, O. & Sahlin, E. 2002: Västergötlands flora. SBT-förlaget, Lund.

Downie, S.R., Ramanath, S., Katz-Downie, D.S. & Llanas, E. 1998: Molecular systematics of Apiaceae subfamily Apioideae: phylogenetic analyses of nuclear ribosomal DNA internal transcribed spacer and plastid rpoC1 intron sequences. Am.Journ. Bot. 85: 563–591.

Hansen, K. 1991: Dansk feltflora. Ed. 5. København.

Hultén, E. & Fries, M. 1986: Atlas of North European vascular plants – north of the Tropic of Cancer. Königstein.

Lid, J. 1974: Norsk og svensk flora. Ed. 2. Oslo.

Malmgren, U. 1982: Västmanlands flora. Lund.

Sterner, R. 1922: The continental elements in the flora of South Sweden. Geografiska Annaler 1922: 221–444.

Sterner, R. 1986: Ölands kärlväxtflora, andra reviderade upplagan. Å. Lundqvist (ed.). Lund.

Svedjemyr, O. 1989: Mästerroten, Peucedanum ostruthium – läkeväxt från medeltid. Svensk Bot. Tidskr. 83: 149–155.

Thellung, A. 1926: Umbelliferae. In G. Hegi (ed.), Illustrierte Flora von Mitteleuropa 5: 926-1537. München.

Tutin, T.G. 1968: Peucedanum L. In T.G. Tutin et al. (eds), Flora Europaea 2: 360–364, Cambridge.