Haloragaceae (the watermilfoil family) is a eudicot flowering plant family in the order Saxifragales, based on the phylogenetic APG system. In the Cronquist system, it was included in the order Haloragales.
Description
The Haloragaceae (alternate spelling Halorrhagidaceae) are very diverse in habit, including both small trees and submerged aquatics. Most members of the Haloragaceae are herbaceous, and most of those in turn are perennials, though some species are annuals. In contrast however, members of the genus Haloragodendron are woody. Most species of Myriophyllum are monoecious while most other taxa have hermaphrodite flowers. The flowers are usually small and inconspicuous, but some genera can have more "showy" conspicuous flowers (Haloragodendron, Glischrocaryon). Flowers are usually radially symmetrical, and unusual for core eudicots, merosity is (2-3)-4 parted. Petals are usually keeled or hooded when present. In Myriophyllum, female flowers usually lack a perianth. They have (2-)4-8 stamens and an inferior ovary of (2-)4 carpels. In Myriophyllum, the fruit is a schizocarp of 1-seeded 'nutlets'. Other genera can have nuts or drupes that can be winged or inflated. The genus Gunnera, formerly included here, are now in the separate family Gunneraceae.
Taxonomy
Molecular phylogenetic studies, in particular, the APG system, placed the Haloragaceae within the core eudicot order, Saxifragales. Earlier versions of the APG had allowed either the broader circumscription (Haloragaceae s.l.) or a narrower Haloragaceae s.s..
Cladogram of Saxifragales families
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Saxifragales
