Aristolochia gigantea aka Duckflower

Aristolochia gigantea is a woody vine in the birthwort family. Its names include Brazilian Dutchman's pipe and giant pelican flower. It comes from humid forests in Central America and Brazil. Its range includes Costa Rica, El Salvador, and Panama. This fast-growing evergreen climbs by twining around a support. Garden plants often reach 15–20 feet [4.6–6.1 metres] tall. Their spread is about 3–6 feet [0.9–1.8 metres]. RHS gives larger sizes: 26–39 feet [8–12 metres] tall, with spreads beyond 26 feet [8 metres].

Older stems have corky bark with deep grooves. The pale green leaves have a heart shape. They grow in an alternate pattern and have smooth edges. Fine, pale hairs cover the undersides of the leaves. Leaves can reach 0.5 feet [0.15 metres] in length. Their width is about 0.33 feet [0.1 metres]. The dense growth can form a screen on a support.

The huge flowers hang alone and form a pouch. Each bloom can reach 2 feet [0.61 metres] long. Its width can reach 1 foot [0.3 metres]. The surface looks like dark red-purple velvet with pale veins. The coloured part is a calyx, rather than petals. The strong, foul scent draws flies, which pollinate the flowers. Missouri Botanical Garden lists bloom time as June to July. In its home range, flowering lasts from summer into winter. The long seed capsules turn from green to brown. They become papery and split, releasing seeds into the wind.

Grow this vine in moist soil that drains well. Loam with a neutral pH suits it. Give it full sun or some shade. Shade helps in sites with intense inland heat. It needs a strong trellis, arbor, or other climbing frame. It also grows in pots, greenhouses, and conservatories. Prune in late winter or early spring when needed. Sources list USDA zones 10–12 and UK hardiness H1B. Temperatures below 30°F can kill the vine.

Sources report few serious pest or disease problems. RHS notes possible honey fungus risk, but the evidence remains limited. This plant is not food and is highly poisonous. Eating any part may cause lasting kidney failure. RHS also warns that it poisons dogs when eaten. Its leaves can kill pipevine swallowtail larvae within three days. It is therefore a poor choice for supporting that butterfly.