Aristolochiaceae
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 Calico Flower (Aristolochia littoralis), about to open
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The Aristolochiaceae, or the Birthwort family, are a family of flowering plants with 7 genera and about 400 species belonging to the order Piperales. The type genus is Aristolochia L.
The Aristolochiaceae are basal dicots (paleodicots), most closely related orders Magnoliales, Laurales, Canellales, and Piperales, which form a clade called the Magnoliids.
Some newer classification schemes, such as the Update of the Angiosperm Phylogeny Group, place the family Aristolochiacea in the order Piperales, but it is still quite common, though superseded, for the Aristolochiaceae to be assigned their own order (Aristolochiales).
They are mostly perennial, herbaceous plants, shrubs, woody vines or even lianas.
The membranous, cordate simple leaves are spread out, growing alternately along the stem on leaf stalks. The margins are commonly entire. There are no stipules.
The bizarre flowers are large to medium-sized, growing in the leaf axils. They are bilaterally or radially symmetrical.
Many members of Aristolochia and some of Asarum contain the toxin aristolochic acid, which discourages herbivores and is known to be carcinogenic in rats. Aristolochia itself is carcinogenic to humans.
Pipevine swallowtail butterflies lay their eggs on pipevine (Aristolochia species), and the larvae dine on the plant but are not affected by the toxin, which then offers the adult butterfly protection against predators.
[edit] Genera
- Apama
- Aristolochia : Pipevine
- Asarum : Wild ginger
- Euglypha
- Holostylis
- Saruma
- Thottea
