Genus Aldrovanda in Family Droseraceae
In botanical taxonomy, a genus (plural genera) is a rank used to group closely related species within a family. In the hierarchy, genus sits below family and above species.
Genera are defined by shared morphological, anatomical, and genetic characteristics (for example, features of flowers, fruits, seeds, or leaves) that indicate a close evolutionary relationship among the species they contain.
Each genus can include one or more species. Examples include Rosa (roses) and Solanum (nightshades, including tomato and eggplant).
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Genus Description
Suggest a correction!Monotypic aquatic Aldrovanda L. belongs to Droseraceae (Caryophyllales), a placement affirmed by APG IV (2016) and the POWO checklist (2024). The type and sole species, Aldrovanda vesiculosa L., makes the genus remarkable for its single species and cosmopolitan aquatic habit.
The plant is a rootless, free‑floating aquatic forming whorls of 6–10 leaves at each node. Each leaf functions as a snap‑trap, 2–4 mm wide, with a sensitive trigger and a hinged blade that closes rapidly on prey. The inflorescence is a solitary, small flower on a short pedicel bearing five sepals, five white petals, five stamens and a style that splits into three stigmas. The ovary is superior, syncarpous and trilocular, with many ovules on a free‑central placenta; the fruit is a dehiscent capsule with numerous minute black seeds (Ellison & Farnsworth, 2012). This suite of traits distinguishes Aldrovanda from terrestrial sundews while preserving the family's snap‑trap mechanism.
Aldrovanda vesiculosa occurs in Old‑World freshwater habitats, from temperate ponds in Europe to tropical swamps in Southeast Asia, Africa and isolated Australian sites. It inhabits still or slow‑moving, often nutrient‑poor waters at low elevations. No major endemism centers are recognised, but regional populations display strong differentiation (Cameron et al., 2009). The species thrives in clear, acidic waters and is sensitive to eutrophication.
Pollination is effected by small insects, principally flies and bees, attracted to the modest white corollas. Dispersal occurs via buoyant seeds that may be carried by water currents or waterfowl; vegetative fragments can also root in suitable substrates. Cytological work reports a base chromosome number x = 10 with 2n = 40 (Bennett & McPherson, 2004).
- Aldrovanda* occupies a monotypic subfamily Aldrovandoideae within Droseraceae, a position supported by molecular phylogenies of the snap‑trap clade that also include Drosera and Dionaea (Cameron et al., 2009). No major recircumscription has been proposed; a minority view treats the genus as a section within Drosera (Ellison & Farnsworth, 2012).
Beyond scientific interest, Aldrovanda is occasionally cultivated in aquaria and research tanks, where its rapid trap response serves as a model for plant movement studies. It has no commercial timber or food value and is not regarded as a weed. Recent assessments list the species as Vulnerable, citing habitat loss, water pollution and competition from invasive macrophytes. Future conservation should prioritize ex situ seed banking and protection of remaining natural habitats to preserve this unique carnivorous lineage.