Callitriche

Callitriche is a genus of largely aquatic plants known as water-starwort. Previously, it was the only genus in the family Callitrichaceae. However, according to the APG II system this family is now included in the Plantaginaceae (plantain family). The family name Callitrichaceae retains its status as nomen conservandum (name to be retained).

Species

 * Callitriche antarctica, Antarctic water-starwort
 * Callitriche brutia, pedunculate water starwort
 * Callitriche christensenii
 * Callitriche fassetti, Fassett's water starwort
 * Callitriche hamulata, intermediate water starwort
 * Callitriche hermaphroditica, autumn water starwort
 * Synonym  Callitriche autumnalis
 * Callitriche heterophylla, differentleaf water starwort
 * Synonym  Callitriche anceps, Callitriche bollanderi
 * Callitriche intermedia, narrowleaf water starwort
 * Callitriche japonica
 * Synonym  Callitriche nana
 * Callitriche longipedunculata, longstalk water starwort
 * Callitriche marginata, winged water starwort
 * Synonym  Callitriche sepulta
 * Callitriche muelleri
 * Callitriche obtusangula, blunt-fruited water starwort
 * Callitriche palustris, spiny water starwort
 * Synonym  Callitriche verna
 * Callitriche pedunculosa, Nuttall's water starwort
 * Synonym  Callitriche nuttallii
 * Callitriche peploides, matted water starwort
 * Callitriche petrieri
 * Callitriche platycarpa, various-leaved water starwort
 * Callitriche pulchra, beautiful water starwort
 * Callitriche sonderi
 * Synonym  Callitriche capricorni
 * Callitriche stagnalis, pond water starwort
 * Callitriche terrestris, terrestrial water starwort
 * Synonym  Callitriche austinii, Callitriche deflexa
 * Callitriche trochlearis, effluent water starwort
 * Callitriche truncata, short-leaved water starwort
 * Callitriche umbonata
 * Callitriche verna

Phylogeny and evolution
The first molecular phylogeny of the aquatic genus of 50 species discerned three clades: Clade A (three species, widespread); Clade C (10 species, New World); Clade D (six species, Europe). The parsimony analyses revealed that aneuploid reduction (n=5 to 4) and polyploidy (n=5 to 10) have evolved at least twice in the genus, whereas the obligately submersed growth habit and hypohydrophily have evolved once.