BIRTHWORT FAMILY (Aristolochiaceae)
This is a family of flowering plants with 7 genera and about 400 species of mostly perennial, herbaceous plants, shrubs, woody vines or lianas.
The heart-shaped leaves have the leaf stem (petiole) attached to the cleft and grow alternately along the stem. The margins are commonly smooth (entire).
The bizarre flowers are large to medium-sized, growing in the leaf axils. They are bilaterally or radially symmetrical.
Many members of the genus 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.
Some butterflies, including the southern Festoon Butterfly (Osterluzeifalter) found in the Lobau, (also certain swallowtail butterflies), lay their eggs exclusively on these plants. The larvae feed on the toxic leaves but are unaffected themselves. The toxin offers the caterpillar, and later the adult butterfly, protection against predators.
(source: Wikipedia)
White
Yellow
Blue
Red
Other
• Backwater
• Marsh
• Damp Grasslands
•Scrub
• Cultivated Fields
• Wayside 
• Dry Grasslands
• Woodland
This plant is poisonous!
It originates in the Mediterranean and has spread to warmer parts of central Europe where it is considered to be a relatively rare species, in some parts endangered.
Stems unbranched, may use surrounding plants for support. Leaves 6 – 10cm long with unusual shape; pointed at tip (typical for pinnate leaves) but with palmate arrangement of main veins, (spreading like the fingers of a hand and connected by network veins). Around the leaf stalk (petiole) the heart-shaped lobes are large and may even overlap.
The ‘Osterluzeifalter’ (‘Southern festoon’ (Zerynthia polyxena) black and cream markings with red spots on the back wings) lays its eggs exclusively on the leaves of this plant. The poison contained in the leaves renders the caterpillars inedible to most predators and this protection is extended to the adult butterfly too.
The yellowish flowers are swollen at the base, have a long tube and funnel- shaped opening with a single point. Small insects slip into the tube and get trapped in the bulbous base, unable to climb out again on account of downward-facing hairs in the tube. They wander about in their trap, brushing against the male and female parts of the flower as they go and feeding on nectar. When pollination is completed, the hairs wilt and they are able to climb out again and visit other flowers where the same thing happens and the process of cross pollination continues. The flowers are able to self-pollinate too if all else fails!
The 1 – 2cm long fruit capsule develops below the bulbous base of the flower, first green and then black and containing many small seeds.