Pilularia
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 Pillwort, Pilularia globulifera
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Pilularia americana A. Braun |
Pilularia is a genus of unusual ferns of family Marsileaceae distributed in North Temperate regions, Ethiopian mountains, and the the southern hemisphere in Australia, New Zealand, and western South America.
Depending on the taxonomic revisor, the genus contains between 3 and 6 species of small plants with thread-like leaves, and creeping rhizomes. The sporangia are borne in spherical sporocarps ("pills") which form in the axils of leaves. Pilularia minuta from SW Europe is one of the smallest of all ferns.
[edit] P. globulifera
Pilularia globulifera, or pillwort, is native to western Europe, where it grows at edges of lakes, ponds, ditches and marshes, on wet clay or clay-sand soil, sometimes in water up to 30cm deep. It has a pea-shaped 4-chambered sporocarp, each chamber with sorus bearing both macrosporangia and microsporangia.
Some of the plants growing in association with this species in the UK include water celery (Apium inundatum), marsh pennywort (Hydrocotyle vulgaris) and lesser spearwort (Ranunculus flammula).
This is an internationally threatened species included in the European Red Data Book. It is listed on Schedule 8 of the Wildlife (Northern Ireland) Order 1985, but it has not been seen since 1970 and may now be extinct in the province. It is protected under the Wildlife and Countryside Act 1981 in the rest of the UK, where it is now classified as Vulnerable.
Pillwort can be grown in a "bog garden" or as a marginal aquatic in a garden pond.
[edit] References
- Preston, C.D. & Croft, J.M. (1997). Aquatic Plants in Britain and Ireland. Harley Books, pp.31-32.
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