| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Limnanthaceae R. Br.

Habit and leaf form. Small, weak marsh herbs. Plants (sub-) succulent. Annual. Helophytic. Leaves alternate; petiolate; simple, or compound; when compound, pinnate, or bipinnate; when pinnate, imparipinnate. Lamina when simple, dissected; pinnatifid, or much-divided; pinnately veined. Leaves exstipulate.

Leaf anatomy. The leaf lamina dorsiventral. Hydathodes commonly present (at the tip of each leaf). Stomata present; on both surfaces (but more numerous below); anomocytic. Minor leaf veins without phloem transfer cells (Limnanthes).

Axial (stem, wood) anatomy. Primary vascular tissues comprising a ring of bundles (with no interfascicular cambium, and lacking the lignified pericyclic ring characteristic of Geraniaceae); collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening absent.

The vessels without vestured pits.

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the androecium (from glands internal and adnate to the antesepalous stamens).

Inflorescence, floral, fruit and seed morphology. Flowers solitary; axillary (on long pedicels); ebracteate; ebracteolate; regular; (4–)5 merous (Limnanthes), or 3 merous (Floerkea); cyclic; tetracyclic, or pentacyclic. Free hypanthium present. Hypogynous disk absent.

Perianth with distinct calyx and corolla; 6–10; 2 whorled; isomerous. Calyx (4–)5 (Limnanthes), or 3 (Floerkea); 1 whorled; polysepalous, or gamosepalous (no more than slightly so). Calyx lobes markedly longer than the tube. Calyx regular; slightly imbricate (Floerkea), or valvate (Limnanthes). Corolla (4–)5, or 3; 1 whorled; polypetalous; contorted; persistent.

Androecium 3 (sometimes, in Floerkea), or 6, or 8, or 10 (persistent). Androecial members free of the perianth; free of one another; 1 whorled (sometimes, in Floerkea), or 2 whorled. Androecium exclusively of fertile stamens. Stamens 3, or 6, or 8, or 10; isomerous with the perianth (sometimes, in Floerkea), or diplostemonous (usually); oppositisepalous; filantherous (the antesepalous members with an internal, adnate nectariferous gland). Anthers dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate. Anther wall initially with more than one middle layer (2). Tapetum glandular. Pollen shed as single grains. Pollen grains aperturate; 2–4 aperturate; colpate (syncolpate), or colporate; 2-celled.

Gynoecium opposite the sepals, (4–)5 carpelled (Limnanthes), or 2–3 carpelled (Floerkea). Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil when considered syncarpous, (2–)3–5 celled. Gynoecium apocarpous (almost), or syncarpous; synstylovarious to eu-syncarpous, or synstylous (very deeply lobed, the almost-separate carpels united by the style, becoming free when ripe); superior to partly inferior (the petals and stamens slightly perigynous). Carpel 1 ovuled. Placentation basal. Ovary if treated as syncarpous, (2–)3–5 locular (but deeply lobed). Gynoecium stylate. Styles 1 (but sometimes more or less deeply cleft); from a depression at the top of the ovary; ‘gynobasic’. Stigmas (2–)3–5; dry type; papillate. Placentation basal. Ovules 1 per locule; ascending; apotropous (the micropyle facing outwards and downwards); with ventral raphe; anatropous; unitegmic; tenuinucellate. Embryo-sac development Drusa-type (with unusual ontogeny, tetrasporic, 4-nucleate in Limnanthes, 6-nucleate in Floerkea). Synergids hooked (large, with or without filiform apparatus). Endosperm formation nuclear. Endosperm haustoria at least sometimes present; lateral (in Floerkea). Embryogeny onagrad.

Fruit non-fleshy; more or less an aggregate, or not an aggregate (if interpreted as syncarpous); interpreted as syncarpous, a schizocarp. Mericarps (2–)3–5; comprising nutlets. Dispersal unit the mericarp. Seeds non-endospermic; with amyloid. Embryo well differentiated. Cotyledons 2 (large); fleshy, cordate. Embryo chlorophyllous; straight.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. Mustard-oils present. Not cyanogenic. Saponins/sapogenins absent. Proanthocyanidins present; cyanidin and delphinidin. Flavonols present; kaempferol, quercetin, and myricetin.

Geography, cytology. Holarctic. Temperate. Temperate North America. X = 5.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Violiflorae; Capparales (re-assigned here, cf. Gadek et al. 1992). Cronquist’s Subclass Rosidae; Geraniales. APG III core angiosperms; core eudicot; Superorder Rosanae; malvid. APG IV Order Brassicales.

Species 11. Genera 2; Floerkea, Limnanthes.

Illustrations. • Le Maout and Decaisne: Limnanthes, Floerkea. • Limnanthes douglasii: Bot. Reg. 20 (1835). • Limnanthes douglasii: Bot. Mag. 64 (1837). • Limnanthes bakeri, photos: © Zoya Akulova (2018). • Limnanthes bakeri, fruiting: © Zoya Akulova (2016).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 8th June 2026. delta-intkey.com’.

Contents