| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Mayacaceae Kunth

Habit and leaf form. Creeping herbs (with a Lycopodium-like habit). Without conspicuous aggregations of leaves. Stem growth conspicuously sympodial. Hydrophytic to helophytic; rooted. Leaves submerged to emergent. Leaves small; alternate; spiral (in high phyllotaxies); imbricate; sessile; non-sheathing; simple. Lamina entire, or dissected (then apically bifid only); linear (or filiform), or lanceolate; one-veined. Lamina margins entire.

General anatomy. Plants without silica bodies.

Leaf anatomy. Stomata present; paracytic. Hairs absent (the plants glabrous save for ephemeral hairs in the leaf axils). Lamina without secretory cavities (but with longitudinal air channels). The mesophyll not containing mucilage cells; without crystals. Foliar vessels present (?), or absent (with ‘vessel tracheids’).

Axial (stem, wood) anatomy. Secondary thickening absent (typically with three vascular bundles, and an aerenchymatous cortex separated from the narrow central cylinder by an endodermis).

The vessel end-walls scalariform, or reticulately perforated.

Root anatomy. Root xylem with vessels; vessel end-walls reticulately perforated and scalariform.

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries absent.

Inflorescence, floral, fruit and seed morphology. Flowers solitary; terminal (but simulating lateral by sympodial growth of the shoots); bracteate (the bracts membranous); small (aerial); regular; 3 merous; cyclic; tetracyclic. Perigone tube absent. Hypogynous disk absent.

Perianth with distinct calyx and corolla; 6; free; 2 whorled; isomerous; different in the two whorls. Calyx 3; 1 whorled; polysepalous; regular; imbricate, or valvate (‘subvalvate’). Corolla 1; 1 whorled; polypetalous; imbricate; regular; pale pink to purple (rose), or white. Petals shortly clawed; entire.

Androecium 3. Androecial members free of the perianth; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 3; isomerous with the perianth; oppositisepalous; alternating with the corolla members; alterniperianthial (representing the outer whorl); filantherous (the filaments slender, glabrous). Anthers basifixed; non-versatile; dehiscing via pores to dehiscing via short slits (apically); bilocular (occasionally), or four locular; tetrasporangiate; appendaged (sometimes). The anther appendages when present, apical (the dehiscence being sometimes at the end of a tubular appendage). Endothecium not developing fibrous thickenings. Microsporogenesis successive. The initial microspore tetrads isobilateral and decussate. Anther wall initially with more than one middle layer; of the ‘basic’ type. Tapetum glandular. Pollen shed as single grains. Pollen grains aperturate; 1 aperturate; sulcate; finely reticulate; 2-celled.

Gynoecium 3 carpelled (the carpels alternating with the stamens). The pistil 1 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 1 locular; sessile. Gynoecium stylate. Styles 1; attenuate from the ovary; apical. Stylar canal present. Stigmas 1, or 3; when single, 1 lobed, or 3 lobed (capitate to trifid). Placentation parietal. Ovules in the single cavity 25–100 (‘many’); horizontal, or ascending; mainly biseriate; orthotropous; bitegmic; thinly crassinucellate, or tenuinucellate. Outer integument contributing to the micropyle. Embryo-sac development Polygonum-type. Synergids pear-shaped. Hypostase present (tanniniferous). Endosperm formation nuclear. Embryogeny onagrad.

Fruit non-fleshy; dehiscent; a capsule. Capsules three valvular (dehiscing midway between the placentae, i.e. each valve with a median placenta). Dispersal probably by water, floating via the air-filled exotesta. Seeds endospermic. Endosperm not oily (mealy, starchy and proteinaceous). Seeds with starch. Embryo rudimentary at the time of seed release. Embryo small, discoid-unipapillate, forming an apical cap on the endosperm at the micropylar end. Testa operculate (with a dorsal ‘embryostega’, cf. Commelinaceae, according to several sources), or non-operculate (Hamann 1961, who treats other reports as erroneous, suggesting that micropylar tissue merely disintegrates); without phytomelan.

Physiology, phytochemistry. Accumulated starch exclusively ‘pteridophyte type’. Not cyanogenic. Proanthocyanidins absent. Flavonols present; quercetin. Ellagic acid absent.

Geography, cytology. Holarctic, Paleotropical, and Neotropical. Sub-tropical to tropical. Southeast U.S.A., Central and tropical South America, tropical Southwest Africa.

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Commeliniflorae; Commelinales. APG III core angiosperms; Superorder Lilianae; commelinid Monocot. APG IV Order Poales.

Species 10. Genera 1; only genus, Mayaca.

Illustrations. • Mayaca kunthii, M. longipes, M. sellowiana and M. vandellii (tecnical details, Fl. Brasiliensis 1842–1871). • Mayaca vanellii: Lindley.

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’.

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