Aethusa cynapium L. map ill.
Linnaeus, Sp. Pl.: 256 (1753). – Type: Linnaean Herbarium 362.1 (LINN) lectotype, sel. by Rechinger, Flora Iranica, 162: 345 (1987).
D Hundepersille. F hukanputki. I villisteinselja. N hundepersille. S vildpersilja.
Literature. Fabri 1989, Fröberg 2000, Reduron 2007, Thellung 1926, Weimarck 1945.
Annual or biennial herb, very variable in size (see varieties), with a simple or branched taproot. Stem solid or hollow; basal part angular to terete; upper internodes angular to sulcate. Leaves with varying number at the base and along the stem (see varieties), one of the five lowest leaves is usually the largest; sheath rather broad, usually not violet, in upper leaves distinctly membrane-bordered and with rounded tips; petiole 1.6–7.5 cm; blade 1–3-pinnate. Primary leaflets 1–5 pairs; angle leaflet/rachis 40–65°, longest petiolules 3–32 mm. Ultimate leaflets 3(–4)-pinnatifid, with 3–6 pairs of lobes; petiolule 5–21(–27) mm; base shortly attenuate to shallowly cordate. Apical lobe with a length/width ratio of 1.3–3.2(–5.3) in lower leaves, and 2.5–7.8(–13) in upper leaves.
Umbels convex, 1.5–2.5 cm high and 2–7 cm wide; rays straight, winged and distinctly papillose on the adaxial side. Bracts 0(–1). Umbellules 5–33; pedicels winged and ± papillose on the adaxial side. Bractlets 2–8 (usually 3), assembled on the abaxial side of the ray and deflexed, persistent; whitish borders only at the base or absent. Flowers ± zygomorphic; sepals absent; petals white with a brown-red midrib, 1–2.2 × 1–2.2 mm, bifid (apical cut 0.4–1.3 mm deep); filaments 0.8–1.4 mm; anthers 0.3–0.4 mm. Fruit ovate in outline, not flattened; carpophore filiform, divided to the base. Mericarps straw-coloured (green as fresh); ridges 5, in cross section high, broad and rounded; valleculae narrow, each with one red-brown vitta; stylopodium flattened to conical, 0.4–0.5 mm wide; style 0.4–0.7 mm, deflexed.
2n=20 (F U). – [2n=20, 22]
Distribution. Nem–SBor(–MBor). – Archaeophytic in the southern parts north to at least southern F, central S and the southern and western coasts of N; a later introduction further north. – D common to fairly common in most areas, but in Jylland scattered in the north and fairly rare in the west. N scattered to rare along the coast and the fjords from Øf to southern SF; further north casual to SNo Vefsn, Tr Tromsø. S common to fairly common north to eastern Dls, southern Vrm, southeastern Vsm and throughout Upl, but less common in the uplands; further north mostly ephemeral, northernmost records Nb Piteå 1908 (ballast) and 2003 (refuse tip), and PL Arvidsjaur 1961 (railway station). F strongly declining but still persistent (or, at least, appearing repeatedly on disturbed ground) in the oldest population centres in the southwest, often in manor or vicarage gardens. Clearly archaeophytic in at least A, V and western U, apparently resident also in the coastal regions of eastern U (Porvoo, Pernaja, Loviisa), in the vicinity of Rauma and Pori in coastal St and in some villages or towns in EK, EH and ES; further north clearly casual (mostly on ballast) in coastal towns: EP Kristiinankaupunki (records 1894–1963), Vaasa between 1880 and 1951, KP Kokkola late 1800s, OP Oulu late 1800s, 1912, 2003 and PeP Kemi 1883. I IVe Reykjavík 1966.
Europe, except the Mediterranean and the extreme north; introduced in North America.
Habitat. In full sun to light shade on dry to mesic ground; preferably on bare nutrient- and mull-rich soil and often in boundary zones in ± man-influenced places, e.g., in gardens, farms, roadsides, fields, ruderal ground, seashores and woodland (details under the varieties).
Biology. Aethusa cynapium has usually been regarded as poisonous; reports on active substances and toxic effects are somewhat contradictory (French 1971, Reduron 2007, Thellung 1926). Flowers all bisexual, except for the central flowers in the umbellules of the tertiary umbels which are usually male.
Variation and taxonomy. Aethusa cynapium is extremely variable in, e.g., life form, size, position of branches, degree of leaf division, pigmentation, length of peduncles, number of rays, and size of bractlets. Several taxa at and below species level have been described within the genus; there is a comprehensive presentation of previous taxonomic views in Thellung (1926). He accepted one species with four varieties, namely var. cynapioides (=var. cynapium sensu Flora Nordica; tall, with short bractlets and leaves with narrow lobes), var. gigantea (tall, with long bractlets), var. domestica (medium-sized, with long bractlets) and var. agrestis (small, annual, with short peduncles and bractlets). Subsequent works have usually accepted only three taxa with varying nomenclature: one small, one medium-sized and one tall.
The tall taxon has been claimed to have bractlets that are either longer than the umbellule (Tutin 1968, Weimarck 1963), or ± shorter than the umbellule (Fabri 1989, Gerstberger 1988, Stace 1991, Mossberg et al. 1992).
The shape of the apical leaf-lobes has also been used to distinguish taxa. Several authors argue that this is not a good diagnostic character because there is variation even within the same individual; however, that is due to heterophylly (the lower leaves have distinctly shorter apical lobes than the upper ones), and the character is useful provided leaves at the same level are studied.
There are certain differences in habitat selection; Reduron (2007) combined habitat preferences and life form with umbel and plant size to distinguish between subsp. elata (a large biennial occurring in natural, ± shady habitats) and subsp. cynapium (a medium-sized to small annual occurring in man-made, ± sunny habitats). Subsp. elata sensu Reduron corresponds to var. gigantea and var. cynapium, which do seem to be more frequent than the other varieties in seminatural habitats also in Norden, but all varieties are frequent in man-made habitats; therefore, habitat is not used here as a character.
As shown in cultivation experiments (Weimarck 1945), A. cynapium is extremely modifiable; less competition gave larger specimens, with umbels having longer peduncles, more umbellules with longer rays, and longer bractlets. Many very small specimens determined to var. agrestis have been found; they are disregarded in the present treatment of infraspecific variation (they were probably dwarfed due to strong competition and might belong to any of the varieties or intermediates). Characters which might be multiple expressions of one gene or gene complex (e.g., the length of the apical leaf-lobes and the length of the bractlets, or the size of the plant and the number of nodes below the primary umbel) should be supported by at least one supposedly independent character for a taxonomic recognition.
Although several of the characters are highly modificative, four fairly distinct groups can be distinguished in the Nordic material, which match the four varieties presented by Thellung (1926). Therefore, his taxonomy is applied here. However, more morphotypes than those that are described here do occur in the area, and all varieties except var. gigantea are somewhat heterogeneous; further studies of phenotype modification and genetic variation within the species, improving our understanding of the systematic importance of different characters, may well lead to a different taxonomic solution.
The accounts were based on specimens only, and a narrow definition of the varieties was used. When only such material that does not deviate much from the typical state of each variety is accepted, only a fairly small proportion of the herbarium material can be determined to variety level; however, the strict definitions made it possible to observe slight differences both in distribution and habitat selection, indicating that the varieties may respond differently to the environment.
For most provinces there are not enough specimens of any of the varieties for a judgement on residency and age; with few exceptions, the status shown is therefore that of the species, but the frequency reflects the number of vouchers.
Nomenclature. The medium-sized taxon with long bractlets (var. domestica sensu Thellung) has usually been regarded as the nominal variety/subspecies of A. cynapium (Thellung 1926, Tutin 1968). However, the specimen of A. cynapium in the Linnaean Herbarium chosen as a lectotype by Rechinger (1987) has short bractlets and narrow leaf-lobes (thus corresponding to var. cynapioides sensu Thellung).
Similar taxa see Conium maculatum and Petroselinum crispum.