Skip to main content

Service Notice

The Western Australian Herbarium’s collections management system, WAHerb, and DBCA’s flora taxonomic names application, WACensus, have been set to read-only mode since 1 October 2025. Recent taxonomic changes are not currently being reflected in Florabase, herbarium collections, or the census. Due to the rapidly approaching holiday season and associated agency and facility soft closures, along with the substantial work involved in data mapping, cleaning, and verification, the migration to the new collection management software is not expected to occur before 1 March 2026, when a further update will be provided. Please reach out to us if you have any questions or concerns.

The notice period started at 9:45 am on Friday, 12 December 2025 +08:00 and will end at 12:00 pm on Monday, 2 March 2026 +08:00.

Advanced Search

Hydatellaceae U.Hamann

Reference
New Zealand J.Bot. 14:195 (1976)
Name Status
Current
Image

Scientific Description

Common name. Hydatella Family.

Family Sometimes included in Centrolepidaceae.

Habit and leaf form. Aquatic herbs. Glabrous annual; plants with a basal concentration of leaves (the stems very short). Hydrophytic to helophytic; rooted. Leaves submerged and emergent; alternate; spiral; sessile; sheathing. Leaf sheaths not tubular; with free margins. Leaves simple; epulvinate. Leaf blades entire; sub- solid, or flat; linear; parallel-veined. Leaves eligulate; presumably with a persistent basal meristem, and basipetal development. Vegetative anatomy. Plants without silica bodies. Stem anatomy. Secondary thickening absent.

Reproductive type, pollination. Fertile flowers functionally male and functionally female. Unisexual flowers present. Plants monoecious (the heads mixed in Trithuria, mostly unisexual in Hydatella). Floral nectaries absent (nectaries lacking). Autogamous or pollinated by water.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in heads; more or less in ‘spikelets’. Inflorescences usually more or less scapiflorous; terminal; with involucral bracts; pseudanthial. Flowers bracteate; ebracteolate; small; 1 merous. Hypogynous disk absent. Perianth absent. Fertile stamens present, or absent (female flowers). Androecium 1 (i.e. the male flower consisting of a single stamen). Androecium exclusively of fertile stamens. Stamens 1. Anthers basifixed; non-versatile; dehiscing via longitudinal slits; bilocular; tetrasporangiate. Fertile gynoecium present, or absent (male flowers). Gynoecium ostensibly 1 carpelled. The pistil 1 celled. Gynoecium monomerous, or syncarpous (perhaps pseudomonomerous, depending on interpretation); of one carpel, or eu-syncarpous; superior. Carpel 1 ovuled. Placentation apical. Ovary (if considered pseudomonomerous) unilocular; 1 locular; shortly stipitate. Gynoecium non-stylate (if a tuft of filamentous structures represents stigmas), or stylate (if it is stylar). Styles free; apical. Placentation apical. Ovules non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy. The fruiting carpel (if considered monomeric) dehiscent, or indehiscent; a follicle, or an achene (Hydatella). Fruit if considered syncarpous dehiscent, or indehiscent; a capsule, or achene-like. Capsules three valvular (Trithuria). Seeds ‘almost’ non-endospermic. Perisperm present (starchy). Seeds with starch. Embryo rudimentary at the time of seed release. Testa operculate. Seedling. Germination hypogeal (seed remnant visible at the base of the plant).

Geography, cytology, number of species. World distribution: Western Australia, New Zealand. 3 species.