Utricularia benthamii is a bladderwort of shallow seasonal wetlands in south-western Australia. Its purple lower flower lip spreads into three distinct lobes beneath a pale upper lip. Seen above receding water, the flower can be conspicuous even when the rest of the plant remains difficult to distinguish from its surroundings.
Name and classification
The accepted name is Utricularia benthamii P.Taylor. The Australian Plant Census record served through the Atlas of Living Australia gives its publication as Kew Bulletin 41: 3, in 1986. APC name record.
Its placement in this series is section Pleiochasia, subgenus Polypompholyx, following the dated species table used for the section guide. Supplementary classification table.
The three-lobed flower
Florabase describes an affixed aquatic annual about 10–25 cm high. The flowering stalk is erect, the calyx has two lobes, and the lower lip is broadly semicircular with three lobes at its tip. Flower colours are recorded as yellow with purple or violet. Western Australian Herbarium: Florabase.
Ng's field account describes flowers reaching roughly 2–3 cm across, with a creamy upper lip and a raised yellow palate above the purple lower lip. The lower lobes form a distinctive T-like outline. He notes smaller lower lips in eastern populations than in western ones. Ng, 2022.
Those observations make a measured photograph more useful than a colour-only comparison. Include the front view for the lower-lip outline and a side view for the spur. A pressed, folded or partly opened flower may not show the same silhouette as a fully open bloom.
Habitat and seasonal timing
Florabase places the plant in clay or peat, in swamps and wet flats, and records flowering in October and November. Its Western Australian distribution includes the Esperance Plains, Jarrah Forest and Warren regions. Florabase habitat and distribution.
Ng describes shallowly flooded swamps and creek systems, generally with clayey substrates, along the south coast and adjacent ranges, with a separated occurrence at Cape Le Grand. Flowering accompanies spring's lengthening days and falling water. Field habitat account.
The important cultivation question is therefore how the accession moves through a wet growing season and a reproductive phase. Its natural setting should be read as a changing water regime, rather than reduced to the single label “aquatic”.
Comparison with Utricularia paulineae
Some U. paulineae flowers share the purple, yellow and cream combination. Ng distinguishes U. benthamii by its clearly three-lobed lower lip, compared with the more continuous outline in U. paulineae. Field comparison.
Retain the identification evidence with the accession. A similar palette does not establish that two plants are the same species, and it should not lead to their seed or divisions being combined.
Reported cultivation from seed
Spence successfully grew U. benthamii from seed using equal peat and sand, cool germination conditions and surface-level water, followed by shallow flooding and a later water recession. He used hand pollination for seed production. VCPS 78, 2005.
Keep the distinction between a documented successful method and an exact physiological requirement. The account does not establish a universal temperature, water depth or light measurement for every accession. When adapting it, record the conditions at germination and flowering, and preserve the seed harvest separately from unsown material.
For an annual, success includes the next seed generation. A flowering pot is one stage of that process. Follow capsule development and label the resulting seed with its source and harvest date so that the next sowing remains traceable.
Reviewed 23 September 2026. Florabase's descriptive record was read directly; the site currently notes a delay in reflecting recent taxonomic changes.
