Lesser water-plantain (Baldellia ranunculoides)
|Also known as:||creeping water-plantain, Crowfoot-alisma|
|Synonyms:||Alisma ranunculoides, Echinodorus ranunculoides|
|Size||Height of subspecies: Baldellia ranunculoides ranunculoides up to 60 cm (2)|
Baldellia ranunculoides repens up to 20 cm (2)
The lesser water-plantain has yet to be globally assessed, but it is classified as Near Threatened (NT) on the IUCN Mediterranean Red List (1).
Like all Baldellia species, the lesser water-plantain (Baldellia ranunculoides) is an aquatic herb (3). This delicate plant has a long, curving stem (4), and the flowers are formed of three relatively short, green sepals (2). Each flower has three dainty petals with rough, ragged edges. The scientific species name of the lesser water-plantain, ranunculoides, means ‘buttercup-like’, although this comparison refers to the seeds rather than the flowers (4).
There are thought to be two separate subspecies of the lesser water-plantain: Baldellia ranunculoides ranunculoides and Baldellia ranunculoides repens (2) (5). These differ from each other in several ways, including the orientation of the flowers and the colour of the petals. B. r. ranunculoides has an erect inflorescence with small white petals, whereas the creeping inflorescence of B. r. repens has longer, wider petals which are usually pink (2) or purple with yellow anthers (6) (7). B. r. ranunculoides only has a maximum of three flowers open per day, whereas B. r. repens has three or four. The petals of both subspecies have faint purple veins. B. r. repens is sometimes known as the creeping water-plantain (2).
The leaves of the lesser water-plantain are arranged spirally around the base of the plant, and are very variable in shape. Submerged leaves tend to be elongated and ribbon-like, whereas floating leaves have more of an oval blade. Both subspecies of the lesser water-plantain have many fibrous, hairless roots (2).
The fruit-heads of Baldellia species are spherical and are composed of several dry ‘nutlets’, which are small one-seeded fruits. B. r. repens typically has more nutlets than B. r. ranunculoides (2).
In all Baldellia species, the fresh stems and leaves have a strong, distinctive coriander-like smell (2).
The lesser water-plantain is native to Europe and the Mediterranean (6), including North Africa and the Middle East (2). The two subspecies appear to have slightly different distributions; while B. r. ranunculoides is found mainly in the coastal, Atlantic regions of western Europe and the Mediterranean (2) (6), B. r. repens is thought to be restricted to the more Atlantic regions of western and northern Europe, and to a few isolated sites in the western Mediterranean. It is thought that the main centre of distribution for B. r. repens lies in western and central France, Belgium and The Netherlands (6).
The lesser water-plantain is generally a lowland species (2) (6), although it has been found at relatively high elevations in parts of its range. In Morocco it has been recorded at elevations of 1,600 metres above sea level (2).
This species occurs in a variety of aquatic habitats, from lakes, ponds and streams (2) (6) to temporary, seasonal water bodies (5) (8). Man-made areas, including canals, ditches and flooded quarries, are also known to be prime habitat for the lesser water-plantain (2).
The lesser water-plantain tends to thrive in areas where there is little competition from other plants for food and other resources (2) (9). Such habitats include naturally open or disturbed areas (2), shallower zones of water (6) (10), and sheltered, muddy shores (4).
B. r. ranunculoides may be found in brackish (6) (8) (9) or calcareous habitats, whereas B. r. repens grows on acidic substrates which are richer in organic matter (6).
The lesser water-plantain exhibits both sexual and vegetative reproduction (2), and the flowers are primarily insect-pollinated (2) (7). In addition, B. r. ranunculoides is capable of self-pollination, whereas B. r. repens requires pollen from a different plant in order for fertilisation to occur and seeds to develop (2).
The seeds of the lesser water-plantain are dispersed by birds or water, and once they have established in suitable habitat, the seedlings will not normally flower until their second year (2). B. r. repens can also reproduce vegetatively, spreading by its creeping runners which give rise to several ‘daughter’ plants (2).
The lesser water-plantain is a brief bloomer (4), with the petals only lasting for a day or so (11). Although this species is generally a perennial plant, it has been known to produce annual forms in temporary pools (2) (11).
The two subspecies flower at slightly different times, with B. r. repens flowering from June to October or November (2) (7), and B. r. ranunculoides from June to August. However, in southern regions, B. r. ranunculoides may flower as early as March (2).
Baldellia species generally require a lot of light for survival, but they are also able to occur in more shaded conditions. However, under such conditions growth is stunted, and the plant has smaller leaves and does not usually produce flowers or fruit. The lesser water-plantain is able to survive in dry conditions for several months, but cannot withstand complete or prolonged desiccation (drying out) of its habitat (2).
The leaves of Baldellia species are used in traditional medicine, as they have a ‘cooling’ effect (2).
The lesser water-plantain is reported to have declined over much of its natural range (3) (6), and it is considered to be the most threatened species within its genus (3).
A multitude of threats affect the lesser water-plantain (2), including habitat destruction (2) (6) (9), competition with other plant species (2) (9), and alterations in water quality (2). Human activities such as draining of fens, flood-control management, and recreational activities are further contributors to the decline of the lesser water-plantain (2). Pollution has also been named as a main threat to this species, as it leads to eutrophication of its aquatic habitat and a potentially detrimental increase in water acidity (2) (3). Eutrophication has been shown to affect the lesser water-plantain both in terms of its morphology and reproduction, with plants on eutrophic substrates being much smaller, and producing far fewer seeds than plants of the same species growing in non-eutrophic conditions (12).
Changes in land use due to agricultural practices can lead to livestock overgrazing and trampling, both of which are known to affect populations of the lesser water-plantain (3).
The lesser water-plantain is included on several regional red lists, and is classified as Endangered in Germany, Norway, Belgium, Luxembourg and The Netherlands (12), and Critically Endangered in Switzerland, Italy and Croatia (2) (12). In Poland, the lesser water-plantain is now listed as regionally extinct (12).
Given that the lesser water-plantain is sensitive to eutrophication, recommendations for future conservation efforts include the need to assess the environmental conditions within sites in which this species occurs. The conservation of the lesser water-plantain could prove vital to other species, as its sensitivity to eutrophication could enable it to be used as an indicator of suitable aquatic habitat conditions for other species (12).
It has been suggested that further research and future conservation efforts for this species need to take into consideration the differences between the two potential subspecies (2) (6).
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- Annual: a plant that lives or grows for just one year.
- Anther: part of the stamen (the male reproductive organ of a flower) that produces pollen.
- Brackish: slightly salty water, usually a mixture of salt and freshwater, such as that found in estuaries.
- Calcareous: containing calcium carbonate, chalky.
- Eutrophication: a process in which a water body is enriched with excessive nutrients (such as nitrogen and phosphorus) resulting in the excessive growth of aquatic plants and the depletion of oxygen, creating unfavourable conditions for other organisms, such as fish.
- Fertilisation: the fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
- Genus: a category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
- Herb: a small, non-woody, seed bearing plant in which all the aerial parts die back at the end of each growing season.
- Inflorescence: the reproductive shoot of a plant, which bears a group or cluster of flowers.
- Morphological: referring to the visible or measurable characteristics of an organism.
- Perennial: a plant that normally lives for more than two years. After an initial period, the plant usually produces flowers once a year.
- Pollination: the transfer of pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.
- Self-pollination: the transfer of pollen from the stamen (male part) of a flower, to the stigma (female part) of the same flower, or a different flower on the same plant.
- Sepal: a leaf-like, usually green part of the protective outer layer of a flower bud.
- Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
- Vegetative reproduction: type of asexual reproduction (reproduction that does not involve the formation of sex cells) in which a new plant grows from part of another plant, rather than from seeds or spores. The resulting individual is genetically identical to the original plant.
IUCN Mediterranean Red List (December, 2011)
- Kozlowski, G., Jones, R.A. and Nicholls-Vuille, F-L. (2008) Biological flora of Central Europe: Baldellia ranunculoides (Alismataceae). Perspectives in Plant Ecology, Evolution and Systematics, 10: 109-142.
- Kozlowski, G., Rion, S., Python, A. and Riedo, S. (2009) Global conservation status assessment of the threatened aquatic plant genus Baldellia (Alismataceae): challenges and limitations. Biodiversity and Conservation, 18: 2307-2325.
Plantlife - Lesser water-plantain (January, 2012)
- Agostinelli, E., Molina, J.A., Pardo, C. and Cafasso, D. (2011) Ecological differentiation and cladogenesis of Baldellia (L.) Parl. (Alismataceae). Plant Systematics and Evolution, 291: 173-182.
- Kozlowski, G. and Matthies, D. (2009) Habitat differentiation in the threatened aquatic plant genus Baldellia (L.) Parl. (Alismataceae): Implications for conservation. Aquatic Botany, 90: 110-118.
- Vuille, F-L. (1988) The reproductive biology of the genus Baldellia (Alismataceae). Plant Systematics and Evolution, 159: 173-183.
- Hurford, C., Schneider, M. and Cowx, I. (2010) Conservation Monitoring in Freshwater Habitats: A Practical Guide and Case Studies. Springer, Berlin.
- Preston, C.D., Pearman, D.A. and Dines, T.D. (Eds.) (2002) New Atlas of the British and Irish Flora. Oxford University Press, Oxford.
- Capdevila-Argüelles, L. and Zilletti, B. (2005) Issues in Bioinvasion Science: EEI 2003 : A Contribution to the Knowledge on Invasive Alien Species. Springer, Berlin.
- Heywood, V.H. (1978) Flowering Plants of the World. Oxford University Press, Oxford.
- Kozlowski, G. and Vallelian, S. (2009) Eutrophication and endangered aquatic plants: an experimental study on Baldellia ranunculoides (L.) Parl. (Alismataceae). Hydrobiologia, 635: 181-187.