Aristolochia is formed from Greek words alluding to the shape of the flower resembling the position of the human foetus prior to birth. Plants are usually climbers, but maybe weakly climbing or trailing. Leaves are alternate, simple often with basal lobes. Flowers are irregular in shape, calyx is coloured and corolla-like, corolla usually reduced or absent, a fetid smell is often present. Fruit a capsule. Pollination by insects and by deceit, they are attracted to the smell and are then trapped and subsequently released to repeat the process. Native species of Aristolochia are host plants for the Cairns birdwing butterfly.