Herbs [subshrubs], annual or perennial, not fleshy [fleshy], autotrophic. Stems prostrate or repent to ascending or erect, often rooting at nodes, 4-angled or weakly so (Micranthemum). Leaves cauline, or basal and cauline [basal], opposite, rarely whorled, simple; stipules absent; petiole present or absent; blade not fleshy [fleshy], leathery or not, margins entire, undulate, or toothed. Inflorescences terminal, racemelike, or axillary, flowers solitary (Micranthemum). Pedicels present; bracteoles absent. Flowers bisexual, perianth and androecium hypogynous; sepals 4 or 5, connate or partially so proximally, calyx radially or bilaterally symmetric; petals 4 or 5, connate, corolla bilaterally symmetric, bilabiate or unilabiate, cylindric, campanulate, or rotate; stamens 2 or 4, adnate to corolla throat, didynamous or equal, abaxial filaments geniculate; staminodes 0 or 2; pistil 1, 2-carpellate, ovary superior, 2-locular (sometimes incompletely in Micranthemum), placentation axile; ovules orthotropous, unitegmic, tenuinucellate; style 1; stigma 1, 2-lobed, capitate or clavate or neither (Micranthemum). Fruits capsules, dehiscence septicidal, poricidal (later septicidal and loculicidal), or irregular. Seeds 15–600, white, yellow, or gold, cylindric, ellipsoid, oblong to narrowly obconic, or irregularly angled, wings absent; embryo straight, endosperm rudimentary.
North America, Mexico, West Indies, Central America, South America, Europe, Asia, Africa, Pacific Islands, Australia, pantropical to temperate, mostly Old World.
Genera 20, species ca. 250 (3 genera, 10 species in the flora).
The genera here included in Linderniaceae were placed traditionally in Scrophulariaceae tribe Gratioleae D. Don (for example, F. W. Pennell 1935 and most subsequent authors). Molecular analyses by D. C. Albach et al. (2005), B. Oxelman et al. (2005), and R. Rahmanzadeh et al. (2005) have contributed to the redefinition of Scrophulariaceae and to the recognition of Linderniaceae, including Micranthemum.
E. Fischer et al. (2013) presented a phylogeny for Linderniaceae based on broad taxon sampling and concluded that, while the family is monophyletic, realignments within the family are necessary. As an example, some species placed traditionally in Lindernia (including three of those occurring in the flora area) were found to be included within segregated genera.
In addition to the molecular data supporting the monophyly of this clade, Linderniaceae are recognized morphologically as a distinct lineage in the Lamiales by possessing abaxial geniculate filaments, expressed in the species of the flora area either in stamens or staminodes. They also lack iridoid compounds and a type of protein body present in the genera previously allied with those now in Linderniaceae (D. C. Albach et al. 2005; R. Rahmanzadeh et al. 2005; D. C. Tank et al. 2006).