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The families of flowering plants

L. Watson and M.J. Dallwitz

Lacandoniaceae E. Martinez & C.H. Ramos

~ Triuridaceae.

Habit and leaf form. Slender achlorophyllous, leafless herbs (with simple stems). Leaves absent. Plants with roots; parasitic; mycoheterotrophic; not green. Perennial; rhizomatous.

Axial (stem, wood) anatomy. Secondary thickening presumably absent.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’. The ultimate inflorescence units cymose (sympodial). Inflorescences terminal; lax, racemelike but sympodial, the flowers spiralled, the pedicels long and ascending. Flowers bracteate (the bracts small, trilobed); ebracteolate; small (4–5 mm in diameter); regular (but with very peculiar organization, the androecium being inserted internally to the carpels); uniquely organized, with the stamens inserted internally to the gynoecium; more or less 3 merous; probably partially acyclic. Probably the gynoecium acyclic. Floral receptacle centrally depressed, with the carpels surrounding the stamens outside the depression. Perigone tube present (short).

Perianth of ‘tepals’; (4–)6 (the members acuminate to caudate tips); joined; without spots.

Androecium (2–)3(–4). Androecial members free of the perianth; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens (2–)3(–4) (inserted on the side of the receptacular depression, persistent); very shortly filantherous (the anthers about 0.3 mm long, the filaments about 0.1 mm). Anthers dorsifixed to basifixed (‘sub-basifixed’); dehiscing via longitudinal slits (the locules dehiscing by a single, common slit); introrse; bilocular; seemingly bisporangiate. Endothecium developing fibrous thickenings. The endothecial thickenings probably girdling. Anther epidermis persistent. Anther wall initially with one middle layer. Pollen grains nonaperturate (and intectate); verrucate; 3-celled.

Gynoecium (50–)60–80 carpelled. Carpels increased in number relative to the perianth. Gynoecium apocarpous; eu-apocarpous (the carpels densely papillose); superior. Carpel stylate; with a lateral style (the styles persistent); 1 ovuled. Placentation basal. Ovules anatropous; bitegmic. Outer integument not contributing to the micropyle. Endosperm formation nuclear.

Fruit non-fleshy; an aggregate. The fruiting carpel indehiscent; an achene. Seeds endospermic; ellipsoid with reticulate ornamentation, distally thickened, with a short basal projection. Embryo rudimentary at the time of seed release, or weakly differentiated.

Geography, cytology. Neotropical. Tropical. Mexico.

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Triuridiflorae (?); Triuridales (?). APG III core angiosperms; Superorder Lilianae; non-commelinid Monocot. APG IV Order Pandanales (as a synonym of Triuridaceae).

Species 1 (Lacandonia schismatica). Genera 1; only genus, Lacandonia.

General remarks. Data encoded here from the original, deficient description and fairly unsatisfactory illustrations: Martinez and Ramos (1989), Máquez-Gusmán et al. (1989). In addition to the transposition of androecium and gynoecium (convincingly confirmed subsequently to the original publication by vertical sections of flowers), Lacandonia differs from Triuridaceae only in the conventional, contracted receptacle and the introrse anthers.

Illustrations. • Lacandonia schismatica: Martinez and Ramos, Ann. Miss. Bot. Gard. 76 (1989). • Lacandonia schismatica (Internet compilation). • Lacandonia schismatica, detailed structure of flower including LS (Martinez and Ramos, Am. J. Bot. 2006).

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: 15th April 2018.’.