The plantain family as traditionally circumscribed consisted of only three genera:
Bougueria,
Littorella, and
Plantago. However phylogenetic research has indicated that Plantaginaceae
sensu stricto (in the strict sense) were nested within
Scrophulariaceae (but forming a group that did not include the type genus of that family,
Scrophularia). Although Veronicaceae (1782) is the oldest family name for this group, Plantaginaceae (1789) is a conserved name under the
International Code of Botanical Nomenclature (ICBN) and thus has priority over any earlier family name for a family including
Plantago. Furthermore, the ICBN does not consider family names published before 1789 to be names eligible for conservation, thus ruling out Veronicaceae. The name
Antirrhinaceae has been proposed for conservation over Plantaginaceae. In the meantime, the Angiosperm Phylogeny Group has accepted the name Plantaginaceae. However, Olmstead (2003) chose to use the name Veronicaceae, a later synonym. The Plantaginaceae is additionally called the veronica family in English. A group of genera including
Lindernia has now been
segregated as the family
Linderniaceae, which is recognized by Haston
et al. 2007 (also known as LAPG II) as "Post-APG II family." Plantaginaceae
sensu lato (in the broad sense) are a diverse,
cosmopolitan family, occurring mostly in temperate zones. The group consists of
herbs,
shrubs and also a few
aquatic plants with
roots (such as the genus
Callitriche). As the family is so diverse, its circumscription is difficult to establish. The
leaves are spiral to opposite and simple to compound. Unusual in Lamiales is the absence of vertical partitions in the heads of the
glandular hairs. The structure and form of the
flowers is variable. Some genera are
4-merous (i.e., with 4
sepals and 4
petals), such as
Aragoa (but this one has 5 sepals); others are 5- to 8-merous, such as
Sibthorpia. The flowers of most genera are polysymmetric. The
corolla is often two-lipped. In some taxa, the
androecium is formed before the corolla. The
fruit is a loculicidal
capsule,
dehiscing through the partitions between the cells. ==Genera==