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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. The Herbarium team, working with the Biodiversity Information Office, now have the Nomos-hosted WACensus in production, and we will begin to update the flora and fungi for WA within the system soon. The Specify project team continues to test and streamline the new collections management system, and we expect this to be online in October. 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 Thursday, 1 October 2026 +08:00.

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Ammannia L.

Reference
Sp.Pl. [Linnaeus] 1:119 (1753)
Name Status
Current

Scientific Description

Family Lythraceae.

Habit and leaf form. Herbs. Annual. Young stems tetragonal. Helophytic to xerophytic. Leaves opposite; usually decussate, or not decussate; subsessile, or sessile; gland-dotted, or not gland-dotted; simple. Leaf blades entire; elliptic, or oblong, or ovate, or obovate, or linear; pinnately veined; cross-venulate; auriculate at the base, or cordate (or attenuate). Leaves without stipules. Leaf blade margins entire. Leaves without a persistent basal meristem. Stem anatomy. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants homostylous, or heterostylous. Entomophilous.

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; in cymes, or in heads, or in umbels, or in fascicles (or clusters). The terminal inflorescence unit cymose, or racemose. Inflorescences axillary. Flowers pedicellate; bracteolate; minute to medium-sized; regular; 4 merous; pentacyclic. Floral receptacle developing an androphore, or with neither androphore nor gynophore. Free hypanthium present; usually campanulate, or urceolate; usually faintly 8-ribbed and glabrous; sinus appendages present or absent. Hypogynous disk present, or absent. Perianth with distinct calyx and corolla; (3–)8–16(–32); 2 -whorled; isomerous. Calyx present; 4; 1 -whorled; gamosepalous; blunt-lobed; lobes valvate; tubular, or campanulate, or urceolate; unequal but not bilabiate, or regular; persistent. Epicalyx present, or absent. Corolla present, or absent; 4; 1 -whorled; polypetalous; plicate; unequal but not bilabiate, or regular; white, or red, or pink, or purple. Petals elliptic, or obovate, or orbicular; sessile. Androecial members definite in number. Androecium 4–8. Androecial sequence determinable, or not determinable. Androecial members free of the perianth; all equal; free of one another; 1–3 -whorled (or several). Androecium exclusively of fertile stamens. Stamens 4–8; attached inside the hypanthium; all more or less similar in shape; reduced in number relative to the adjacent perianth to isomerous with the perianth to polystemonous; alternisepalous, or oppositisepalous; inflexed in bud, or erect in bud. Anthers dorsifixed; versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate. Gynoecium 2–4(–6) carpelled. The pistil (1–)2–4 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary unilocular, or plurilocular; (1–)2–4 locular; sessile to stipitate. Gynoecium stylate. Styles 1; apical. Stigmas 1; capitate. Placentation rarely (i.e.when unilocular), parietal; axile. Ovules (1–)5–50 per locule; ascending, or horizontal; non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule. Capsules splitting irregularly to circumscissile, or septicidal to valvular. Seeds non-endospermic; wingless. Cotyledons 2. Embryo straight.

Etymology. After Johannes Ammann (1797–42), German professor of botany at Leningrad (then St Petersburg); or (less likely) Paul Ammann (1634–91), professor at Leipzig.