Utricularia tenella is a small Australian bladderwort whose pink flowers reward close inspection. Its divided corolla and four-part calyx place it among the most distinctive-looking members of the genus, while its annual life cycle makes seed production central to maintaining it through successive seasons.
Name and placement
The accepted name is Utricularia tenella R.Br., first published in 1810. Plants of the World Online records it as an annual native to Western Australia, South Australia, Victoria and Tasmania. Kew POWO: Utricularia tenella.
It belongs to section Polypompholyx within the broader subgenus of the same name. The section contains U. tenella and U. multifida; U. westonii belongs to the related section Tridentaria. Płachno and colleagues, 2019.
Recognising the plant
VicFlora describes a terrestrial annual with leaves arranged in a rosette. The narrow, spoon-shaped leaves are 3–10 mm long, and its flowering racemes are 2.5–13 cm long with one to three flowers. The corolla is 3–9 mm long, pink with yellow at the palate margin. Its upper lip divides deeply into two pointed lobes, while the broader lower lip divides into three. The calyx has two outer and two inner lobes. VicFlora species description.
Photograph both lips, the spur and the calyx when documenting an identification. Overall smallness is useful context, but size alone is a poor substitute for the combination of characters. Record whether the measurements concern the corolla, the flower stalk or the whole plant.
Habitat and flowering season
In Victoria, the species occurs in wet heath and seasonally wet woodland depressions, with flowering recorded from September to December. VicFlora notes that the Tasmanian occurrence is on Bass Strait islands. Those regional details make the broad state-level distribution more informative. VicFlora habitat and distribution.
A flowering interval from a regional flora describes records in that region. It should not be converted into a guarantee that every cultivated accession flowers in the same month, particularly when grown in a different hemisphere or an artificially controlled environment.
Flowers as more than an ornament
A 2019 study examined the floral glands and nectar of U. tenella and related species. It found nectar dominated by glucose and fructose, produced and retained in the spur. The authors also examined hairs at the flower entrance and suggested a visual-attraction role for some of them. This adds microscopic detail to the conspicuous flower without establishing a single exclusive pollinator. Płachno and colleagues, 2019: floral micromorphology.
Documented cultivation
Sean Spence reported growing U. tenella from seed in Melbourne. His seasonal method used late-summer sowing, equal parts peat and sand, a high water table and a cool position for germination, followed by increased light as seedlings developed. He did not find extreme heat pretreatment necessary. This is a documented grower's method, not a controlled determination of optimal conditions. Spence, 2005, pages 12–14.
For a new accession, preserve the seed's source and storage history and record sowing, germination, flowering and capsule development separately. Do not assume a perennial division routine will maintain an annual plant indefinitely. Successful cultivation includes carrying the lineage into the next generation.
Names encountered in older references
POWO lists Polypompholyx tenella, Vesiculina tenella, Polypompholyx exigua and Tetralobus pusillus as synonyms. Its checked record lists no accepted infraspecific taxa. The older genus name therefore provides a route to the same species, rather than an additional species for the collection list. Kew nomenclatural record.
Reviewed 22 September 2026. Identification and range follow the cited botanical records; cultivation is attributed to the grower who reported it. No cultivar status or nursery availability is implied.
