Crepis paludosa (L.) Moench, Marsh Hawk's-beard

Account Summary

Growth form and preferred habitats

The Hawk's-beard genus Crepis is characterised by achenes which taper towards the top, crowned by a white, unbranched pappus. C. paludosa, however, is exceptional in possessing a brownish or dirty yellowish-white pappus and its achenes are only very slightly narrowed above, so that it is very similar to a Hawkweed, Hieracium spp. (Silverside 1990). The similarity to a Hieracium is reflected by the fact that C. paludosa was previously known as H. paludosum, amongst no less than 14 other synonyms (Sell & Murrell 2006). In shaded situations, the pappus of C. paludosa tends to persist into the autumn and this, together with the shining, hairless, shallowly-lobed basal leaves that are thin and soon disappear, and the stem leaves with pointed leaf-bases (auriculate) which clasp the stem, assist in distinguishing it from any true Hieracium species.

The genera Crepis and Hieracium are closely allied and, indeed, Stace (1997) actually comments that they are, "doubtfully distinct". Both genera show the same range of form, varying from fairly small plants with most of their leaves forming a basal rosette, to tall, robust species with stem-leaves that are just as well-developed as those of the plant basal rosette (Silverside 1990).

C. paludosa is a perennial with a short, stout, woody rhizome and a solitary flowering stem 25-100 cm tall. It is hairless except for the inflorescence that bears a dense coating of blackish hairs on the involucral bracts (Sell & Murrell 2006). Marsh Hawk's-beard is most typically found in constantly cool, damp, moist sites, such as near waterfalls, by upland streams, on wet, N-facing cliffs, in narrow, shady ravines and in spring flushes on bogs. It is not confined to upland sites, however, and is also found particularly where there is some water movement in the soil, in swampy woods, moist or wet meadows, calcareous fens, lakeshores, ditches and on roadside verges (Sinker et al. 1985; P.A. Stroh & F.H. Perring, in: https://plantatlas2020.org/atlas/2cd4p9h.ry, accessed 29 June 2023).

It is regarded as a plant of sunny to half-shade, fairly infertile, moderately acid to neutral soils (even when these occur over limestone), which fits well with the heavily leached soils of many of its Fermanagh sites (Hill et al. 1999). It is absent, however, from strongly acidic, deep peat areas.

In meadows, C. paludosa is eliminated by heavy grazing, but it can tolerate occasional mowing for hay or silage. It is capable of persisting in fairly dense, tall herb vegetation in damp to wet valley meadows (Sinker et al. 1985). The established strategy of C. paludosa is categorized as a CSR species, ie a balance of all three strategies, Competitor, Stress-tolerator and Ruderal (Grime et al. 1988, 2007)

Flowering reproduction

Despite possessing a rhizome (which is short and woody), the species relies entirely on seed for its reproduction. Living as it normally does in damp, shady situations, it is not really surprising that C. paludosa is late flowering, blossom appearing from July to September. The golden-yellow flowerheads are borne in a loose corymb and are relatively few in number (1-15), in relation to the size of the plant. The involucral bracts (phyllaries) of the flowerhead are clothed with black spreading hairs with glandular tips, the hairs also continuing a short way down the stalk (Hutchinson 1972). The flowers are all ligulate and the species is pollinated by flies and bees (Clapham et al. 1962).

The achenes are ten-ribbed, hairless and lack beaks, but they are distinguished from other Crepis species by the stiff, brittle, dirty or greyish-white pappus of hairs (Melderis & Bangerter 1955). The current author (RSF) has not been able to uncover any statistics in references available to him regarding the scale of seed production or the efficiency of dispersal. It is known, however, that Crepis achenes have been found adhering to the rough coats of sheep, goats and other stock animals (Ridley 1930, p. 554).

Germination of freshly collected seed was 76% in trials by Grime et al. (1981) and 30% after dry storage for one year. This indicates that after-ripening is not required and it also suggests (but does not confirm) that prolonged survival in the soil seed bank is unlikely. The survey of soil seed banks in NW Europe lists five estimates of buried seed survival, four of them concluding it is transient (ie persists for less than one year), while the other study recognised seed was present in soil but could not determine its persistence (Thompson et al. 1997).

British and Irish occurrence

C. paludosa is essentially a northern species, widespread but local in the N & W of Britain, although absent entirely below a line from The Wash to the Severn (BSBI Atlas 2; New Atlas; Atlas 2020). In Ireland, it is frequent only in the N and NW and is rather rare elsewhere, although more systematic, concerted recording for the Atlas 2020 has extended its known distribution to the S & SW coasts. Despite the appearance of the hectad map in the New Atlas, this species has been recorded in every Irish VC except Longford (H24) (Cen Cat Fl Ir 2; An Irish Flora 1996).

Fermanagh occurrence

C. paludosa has been recorded in 196 Fermanagh tetrads, 37.1% of the VC total. It is very widely scattered across the county, but is particularly frequent in the more upland west. C. paludosa is more than twice as frequently recorded in the VC as the related annual, C. capillaris (Smooth Hawk's-beard).

European and world occurrence

C. paludosa belongs to the European boreo-temperate phytogeographical element and is widespread in N & C areas of Europe, its distribution stretching north to reach 70^o 30' in Norway and southwards to N Spain, the toe of Italy, S Bulgaria and SC Russia. In the south, however, it is absent from most of France and from all the Mediterranean islands (Tutin et al. 1976; Hultén & Fries 1986, Map 1933; Sell & Murrell 2006).

Threats

None.

References

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