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Taxa treated:
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 © Flora Nordica

by Lars Fröberg
(6b, 200900616)

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Oenanthe L.

Linnaeus, Sp. pl.: 254 (1753).
Phellandrium L. (1753).
Terrestrial or aquatic, glabrous herbs; submerged leaves finely dissected. Umbellules compact, with the central flowers sessile or short-stalked. Sepals well-developed, persistent, forming a crown on the ripe fruits. Fruit without a carpophore (the entire adaxial sides of the mericarps are connected); ridges with large, air-filled cavities.
Chromosome base-numbers x=10, 11.
Biology. Roots, flowers and fruits may contain poisonous polyacetylenes (e.g. falcarinol and falcarinone).
1 Terminal lobes of upper (aerial) leaves longer than 1.2 cm; the central flowers of each umbellule sessile to subsessile (outer flowers distinctly stalked)
- Terminal lobes of upper (aerial) leaves shorter than 0.85 cm; all flowers distinctly stalked
2 Petiole, rachis and stem internodes inflated; rays up to 7; bracts 0 or 1
- Not inflated; rays 9 or more; bracts 4–8
3 Stem base vertical, distinctly inflated; inundated leaves (if present) with capillary lobes; fruit shorter than 5 mm
- Stem base ± creeping, not inflated; inundated leaves always present, with flat lobes; fruit longer than 5 mm

1. Oenanthe fistulosa L.       map

Linnaeus, Sp. pl.: 254 (1753). – Type: Clifford Herbarium 99, Oenanthe 1 (BM) lectotype, sel. by Reduron & Jarvis, Regnum Veg. 127: 70 (1993).
D Vand-Klaseskærm. F pulleapahaputki. S pipstäkra.
Helophyte or hydrophyte. Heterophyllous aquatic perennial, to 90 cm, with roots and usually also stolons emanating from the lower nodes; roots swelled, c. 2 mm thick. Stem widely hollow and inflated; basal part 3–8 mm thick, easily compressed, terete with elevated veins, purplish or sometimes green, glaucous or not. Leaves 5–8 on the stem (the lower ones 1–2-pinnate, usually withered at anthesis); narrow-lobed basal leaves sometimes present in submerged plants (lobes 2–3.5 × 0.5–0.8 mm). Middle leaves 1-pinnate; sheath distinct but not inflated, 0.5–2.5 cm long, not purplish, distinctly membrane-bordered; petiole 6–13 cm, widely hollow and inflated (the rachis too); blade 4.5–9.5 × 1.5–4 cm (length/width ratio 2.3–3.8). Primary leaflets 4–7 pairs; angle leaflet/rachis 35–60° (in lower leaves 60–130°); longest petiolule up to 10 mm. Apical leaflet indistinctly delimited from the rachis (in lower leaves 2-pinnatifid, with 1–2 pairs of primary lobes); petiolule 3–6 mm; blade 6–13 × 7–15 mm (length/width ratio 0.8–1.1); margin not papillose; base broadly cuneate to truncate. Apical lobe 12–27 × 1.2–2.3 mm, with a length/width ratio of 7–22, cuspidate to acuminate, with purplish or white tips (in lower leaves 2–7 × 1.6–2.2 mm, with a length/width ratio of 0.9–4.4).
Umbels with a (0–)2–13 cm long peduncle; rays 1.2–2 cm, thick, usually glabrous, with distinct ribs. Bracts 0–1. Umbellules 2–5(–7); pedicels 0.2–0.5 mm, not papillose (central flowers sessile). Bractlets 6–12, persistent, 1.4–3.5(–5) × 0.4–1(–1.7) mm, membrane-bordered. Flowers 24–52 per umbellule; sepals 1–2.2 mm; petals white or red-tinged, 2.8–4.5 × 1.5–2.8 mm, bifid (apical cut 0.9–1.7 mm deep); filaments 3.2–4.5 mm; anthers purplish to pale violet, 0.4–0.5 mm. Fruit prismatic, triangular to obovate in outline, yellow-brown, not splitting at maturity (spread as a unit). Mericarps 3–4.5 × 1.7–3.1 × 1–1.7 mm (length/width ratio 1.2–2); ridges 9, the lateral ones in cross section with large cell cavities; vittae not visible on the surface; stylopodium conical, gradually turning into the style, 0.6–1.2 mm wide; styles 3.5–5 mm, directed upwards to somewhat outwards, with a capitate stigma. – Mid-summer to late summer.
Distribution. Nem. – Declining throughout. D scattered in the islands and southeastern Jylland, fairly rare in VJy (e.g. the streams Skjernå and Vorgodå) and NJy. S scattered in the lowlands of Sk and in northern Gtl; earlier also in Hl (Träslöv, Veddige and several localities in the southwest, latest record Laholm 1933), Bl Sölvesborg until 1895, Klm 4 localities near Kalmar (latest Hagbyån 1919 and Hossmoån 1922; see Edqvist & Karlsson 2007).
W, C and S Europe, and NW Africa.

Habitat. In and at shallow, eutrophic freshwater (often on seasonally inundated ground), in sunexposed places; dependent on bare soil (e.g., kept open by trampling). Lakeshores, pools, rivers, and ditches. Sensitive to overgrowth and drainage; favoured by lime.

Biology. Umbellules have bisexual, ± sessile central flowers and male, pedicellate peripheral flowers; the latter are enlarged and act as means for pollinator attraction. The fruits are adapted to water-dispersal (enlarged cell cavities in the ridges); the plant is also vegetatively spread with stolons.

2. Oenanthe lachenalii C.C. Gmel.       map       ill.

Gmelin, Fl. Bad. 1: 678 (1805). – Described from Switzerland.
D Eng-Klaseskærm. F kaitapahaputki. S smalstäkra.
Helophyte or hemicryptophyte. Heterophyllous aquatic or terrestrial perennial, to 70(–100) cm; roots swelled, 1-2 mm thick. Stem solid or secondarily hollow; basal part 2.5–4(–6) mm thick, terete, angled or slightly sulcate, violet, distinctly glaucous. Leaves 5–7 on the stem, the lower ones (usually withered at anthesis) smaller, with broader leaflets than the middle ones. Lower leaves 1-pinnate; blade 3–6.5 x 2–3 cm; primary leaflets 2–3 pairs; apical leaflet 1–2-pinnatifid, with 1–2 pairs of lobes, 10–14 × 8–13 mm (length/width ratio 0.8–1.5), with a 5–9 mm long petiolule, a broadly attenuate to cordate base, and a thickened and slightly revolute margin (slightly papillose towards the apex); apical lobes 2.5–5 × 1.4–2.5 mm (length/width ratio 1–2.5), cuspidate to acuminate, with purplish tips. Middle leaves with a 2.5–4 cm long sheath; petiole 10–14 cm; blade (1–)2-pinnate, 9–10 × 5–6 cm (length/width ratio 1.7–1.8); primary leaflets 3–4 pairs, with a leaflet/rachis angle of 35–45°; apical leaflet indistinctly delimited from the rachis and therefore not measured; apical lobe 23–63 × 1.2–2.3 mm (length/width ratio 16–31).
Umbels with a 1–11 cm long peduncle; rays 1.5–3 cm, glabrous, with distinct ridges. Bracts (4–)6–8, persistent, 5–8(–11) × 0.3–0.9 mm, usually distinctly membrane-bordered. Umbellules 9–16; pedicels 0.2–0.5 mm, glabrous. Bractlets 12–14, persistent, 2–3.5 × 0.4–0.7 mm, distinctly membrane-bordered. Flowers 30–43; sepals 0.5–1 mm; petals white, 1.2–1.7 × 1–1.4 mm, bifid/emarginate (apical cut 0.4–0.7 mm deep); filaments 1.2–1.6 mm; anthers pale, 0.35–0.5 mm. Fruit obovate in outline, greenish brown, usually distinctly violet-tinged, not splitting at maturity (spread as a unit). Mericarps 2.1–2.6 × 0.9–1.5 × 0.5–0.9 mm (length/width ratio 1.6–2.3); ridges 5, the lateral ones with large cell-cavities; vittae visible on the surface; stylopodium 0.3–0.5 mm wide, conical, gradually turning into a thick style with an indistinct stigma; style 0.6–1.4 mm long, directed upwards to somewhat outwards.. – Mid-summer.
[2n=20, 22]
Distribution. Nem. – D scattered on the coasts of FyL (especially in the southern parts) and Sjæ (in the southern parts and at Isefjord); LFM Nykøbing, SJy around Haderslev, ØJy Juelsminde, NJy Ålborg and Thisted. S Bl Ronneby (4 localities close to Ekenäs, known since 1927).
W Europe and the NW Mediterranean.

Habitat. Seashore meadow and coastal reed-swamp (in thin Phragmites australis or Schoenoplectus maritimus stands).

Biology. The fruits are adapted to short-distance water-dispersal (the ridges have enlarged cell cavities).

Variation. Plants from S Bl deviate, having (35–)39–42 flowers per umbellule (those from D have 30–40 flowers) and perhaps also slightly more bracts and bractlets. The differences may be due to genetic drift in the very small Swedish population, or to different origins.

Similar taxa. Oenanthe lachenalii is similar to Oenanthe pimpinelloides (rare casual).

3. Oenanthe aquatica (L.) Poir.      map       ill.

Poiret in Lam., Encycl. meth. bot. 4: 530 (1798). – Phellandrium aquaticum L., Sp. pl.: 255 (1753). – Oenanthe phellandrium Lam., nom illeg. (1779). – Type: Clifford Herbarium 100, Phellandrium 1 (BM) lectotype, sel. by Reduron & Jarvis, Regnum Veg. 127: 75 (1993).
D Billebo-Klaseskærm. F liejupahaputki. N hestekjørvel. S vattenstäkra.
Helophyte, hydrophyte or therophyte. Aquatic annual or biennial, usually heterophyllous when growing in water, to 100 cm. Stem sometimes rooting at the lower nodes, hollow; basal part 6–22(–28) mm thick, distinctly widened (sometimes even conical), terete, straw-coloured or slightly purplish, not or indistinctly glaucous; upper internodes ± sulcate. Leaves 7–16 on the stem, submerged ones narrow-lobed (basal ones usually withered at anthesis). Broad-lobed  leaves 2–3-pinnate; sheath 1–4 cm, fairly broad, not purplish, distinctly membrane-bordered; petiole 4–12 cm; blade thin, 5–19 × 3–11 cm (length/width ratio (1.1–)1.4–2.1). Primary leaflets of broad-lobed leaves 6–8 pairs; angle leaflet/rachis (85–)110–130(–150°); longest petiolules 5–22 mm. Ultimate leaflets of broad-lobed leaves 2(–3)-pinnatifid, with (2–)3–4 pairs of lobes; petiolule 2–9 mm; blade 6–24 × 5–19 mm, with a length/width ratio of 1–1.4(–1.8); base shallowly cordate to truncate (rarely broadly attenuate); margin not or indistinctly papillose; ultimate lobes 1.7–6(–8.5) × 0.9–2(–2.5) mm, with a length/width ratio of (1.4–)1.9–3.5(–4.4), cuspidate to acuminate (rarely acute); tips usually hyaline. Narrow-lobed leaves 4–5-pinnatifid with 3–6 × 0.1–0.3 mm large terminal lobes.
Umbels slightly convex, 2–3 cm high and 5.5–8 cm wide; peduncle 0.5–3.5 cm; rays straight or slightly inwards-curved, 2–3.5 cm, glabrous or slightly papillose, with distinct ridges on the adaxial side. Bracts 0(–1). Umbellules 7–14(–17); pedicels 0.3–0.6 mm, not or indistinctly papillose on the adaxial side. Bractlets 5–11, persistent, 2.5–5(–7) × 0.3–0.6(–0.7) mm, sometimes distinctly membrane-bordered. Flowers 17–27(–41); sepals 0.4–1.2 mm; petals white, (1.1–)1.5–2.4 × 1–1.8 mm, with a folded apex, emarginate (apical cut 0.1–0.7 mm deep); filaments 1.5–2.5 mm; anthers dark violet, 0.3–0.5 mm. Fruit ovate in outline, without or with an indistinct groove between the mericarps, usually slightly bent towards the centre of the umbellule, falling apart at maturity. Mericarps 3.1–5 × 1.1–1.6(–2) × 0.9–1(–1.2) mm (length/width ratio 1.8–3.7); ridges 5, greenish to yellow-brown, low, with large, air-filled cavities (lateral and dorsal ones ± equal in size); valleculae narrow with dark brown vittae; stylopodium conical, 0.3–0.5 mm wide; style 0.8–1.2 mm, directed upwards to somewhat outwards. – Mid-summer to late summer.
Distribution. Nem–BNem (SBor). – Declining in parts of the distribution area. D common to rather common on the eastern islands; scattered in most of Jylland, but rare to absent in the central and northernmost parts; Brn Klemenskjer (extinct). N Øf Rygge (still present), Fredrikstad until 1978, Ak Oslo 1860, Vf Tønsberg until 1993. S scattered to fairly rare in southern lowland areas north to southern BhG, the shores of Vänern in Dls and Vrm, eastern Vsm, southeastern Dlr and Gst (but absent from much of the southern upland, rare in Öl and not known from Gtl); 19th century records also from Hls Arbrå, Delsbo and Ljusdal and Mpd Timrå. F A Geta (Bolstaholm) and Jomala (Dalkarby träsk), northwestern V Laitila and Pyhäranta (two nearby localities on the shore of Lake Otajärvi), several populations in river mouths in western central St (Rauma, Eurajoki, Noormarkku, Pori, Ulvila, Merikarvia), isolated inland records from EH Janakkala 1931, 1960 and 1966.
Europe except the SW and N parts, W Siberia.

Habitat. Shallow, eutrophic, usually still or slow-flowing freshwaters with clay- or mud-bottom, in full sun to half-shade. Pools, slow moving rivers and seashores; also in alder cars as well as man-made places, e.g. ditches, peat-cuttings and millponds. Disfavoured by drainage and by overgrowth of no longer grazed shores.

Biology. Most flowers are bisexual. The fruits with large, air-filled cavities in the ridges are adapted to water-dispersal; long-distance spreading is probably not important, since the fruits can float for a few days only. Short-distance spreading with swelled stem-bases also occurs.

Similar taxa. Records of Oenanthe aquatica are sometimes based on the much more common Peucedanum palustre, which has leaflets inserted to the rachis at an angle of 30–50(–70°), longer peduncles (4.5–17 cm), several bracts, and mericarps with distinct wings. – For Oenanthe fluviatilis see the key.

4. Oenanthe fluviatilis (Bab.) Coleman       map       ill.

Coleman, Ann. Mag. Nat. Hist. 13: 188 (1844). – Oenanthe phellandrium var. fluviatilis Bab., Manual Brit. Bot., ed. 1: 131 (1843). – Described from Great Britain.
D Flod-Klaseskærm. F jokipahaputki. S flodstäkra.
Usually hydrophyte. Heterophyllous, aquatic perennial, to 80 cm, with only the upper part above the surface (or completely submerged). Stem hollow; basal part creeping and rooting, 4–13 mm thick, terete, greenish and not glaucous; upper internodes sulcate. Leaves 6–8 on the stem, the aerial ones (if any) broad-lobed. Narrow-lobed leaves 2–3-pinnate; sheath 3–6 cm, fairly broad, not purplish, distinctly membrane-bordered; petiole 11–26 cm; blade thin, 17–28 × 8–20 cm (length/width ratio c. 2). Primary leaflets of narrow-lobed leaves 4–6 pairs; angle leaflet/rachis 30–45°; longest petiolules 12–34 mm. Ultimate leaflets of narrow-lobed leaves 2–3-pinnatifid, with 4–6 pairs of lobes; petiolule 4–18 mm; blade 17–55 × 8–18 mm (length/width ratio 1.9–3.7); base cuneate; ultimate lobes 2–13 × 0.5–0.8 mm (length/width ratio 4–22), with acute apex. Broad-lobed leaves 2-pinnate with 5 pairs of primary leaflets and a leaflet/rachis angle of (45–)70–110(–130°); ultimate leaflets 2-pinnatifid, with 3–4 pairs of lobes, 15–26 × 11–22 mm (length/width ratio 1–1.4), with a broadly attenuate to shallowly cordate base; margin not papillose; ultimate lobes (2.5–)3.7–7.5 × 1–2.2(–2.6) mm (length/width ratio 1.9–4.5), acute to cuspidate and usually with reddish tips (often blackened when dried).
Umbels almost flat, 2.5–4.5 cm high and 7–15 cm wide; peduncle 1–3.5 cm; rays straight, 3.1–7 cm long, glabrous, with distinct ridges on the adaxial side. Bracts 0. Umbellules 5–11; pedicels 0.5–0.8 mm, glabrous or indistinctly papillose on the adaxial side. Bractlets 6–10, persistent, 2.5–6.5 × 0.4–0.5 mm, sometimes distinctly membrane-bordered. Flowers 12–25(–41); sepals 0.4–0.9 mm; petals white, 1.5–2.5 × 0.9–1.5 mm, with a folded apex, emarginate/bifid (apical cut 0.3–0.6 mm deep); filaments 1.8–2.5 mm; anthers dark violet or brownish violet, 0.4–0.6 mm. Fruit oblong in outline, with a distinct groove between the mericarps, often distinctly bent inwards towards the centre of the umbellule, falling apart at maturity. Mericarps 5–6 × 1.2–1.5 × 1–1.2 mm (length/width ratio 4–4.2); ridges 5, dark greenish brown, low, usually with a minute furrow on the edge, and with large, air-filled cavities (lateral ones distinctly larger than dorsal ones); valleculae narrow with black-brown vittae; stylopodium conical, 0.5 mm wide; style 1–1.1 mm, directed outwards. – Mid-summer.
Distribution. Nem. – D VJy the Skjernå water system (at Borris, Felding, Barde and Arnborg), Storå (at Holsterbro), Vardeå/Lindingå (at Nørholm); ØJy Ebeltoft 2006 (pond, probably casual).
W Europe.

Habitat. Eutrophic, slowly running water, at a depth of 0.5–2 m.

Similar taxa. Oenanthe fluviatilis is similar to O. aquatica but is usually ± completely inundated and the lobes of inundated leaves are at least 0.5 mm wide (in O. aquatica only the basal part is inundated and the narrow-lobed leaves, if any, have up to 0.3 mm wide lobes; see also the key).

Rare casual 

Oenanthe pimpinelloides L. 1753. S knölstäkra. – Lit.: Tutin (1980; ill.). – Similar to O. lachenalii, but roots abruptly widened into an ovoid swelling a few cm from the stem base, umbel rays thickened at fruiting stage, and styles longer (almost as long as the rest of the mericarp). – [2n=22]
S Bl Augerum 1947 (Kummeln, escaped from garden). – W and S Europe. – Sometimes used as a root vegetable; however, the tubers are poisonous. – Map (not in the book).

References To top

Egholm, B. 1951: Umbelliferernes udbredelse i Danmark. Danmarks Topografisk-Botaniske Undersøgelse no. 16. Bot. Tidsskr. 47: 373–480.

Tutin, T.G. 1980: Umbellifers of the British Isles. B.S.B.I. Handbook 2.