Aristolochia watsonii (Watson's Dutchman's pipe, southwestern pipevine, Indian root, snakeroot) is a perennial plant[1] in the birthwort family (Aristolochiaceae), found growing among plants of the Arizona Uplands in the Sonoran Desert.[2] The plant is inconspicuous,[2] small and hard to spot, but can be found by following the pipevine swallowtail (blue swallowtail, Battus philenor) which lays eggs on it.[1]
It grows as vine with scrambling stems that create a dense, tangled mat over the years when growing on open ground.[1] [2]
According to one source, stems are 6to long, with greenish-brown arrowhead-shaped NaNto leaves.[2] Another source states stems can reach 3feet, in dense mats that are 1to wide.[1] It drops its leaves in the fall and winter (cold-deciduous), and loses stems as well as leaves in a freeze.[1] In full sun and drought conditions, leaves turn from green to purple-brown.[1]
It has "bizarre" looking, musky-smelling flowers, which resemble the ear of a rodent.[2] It blooms from April to October. 1to flowers are shaped like a rodent's ear[1] [2] are green or burgundy-brown outside to the ear rim, then green speckled with burgundy-brown inside, with hairs on the opening ear rim.[2] Flowers last 1–2 days.[1]
Fruits are capsules having five vertical ribs with triangular-shaped flat and black seeds in each of five compartments.[1]
Flowers shaped and smelling like a rodent's ear attract small blood-sucking flies, which are deceived by the appearance and odor and get trapped in the convoluted flower form for a day, then escape to pollinate another plant.[1] [2] It attracts the pipevine swallowtail,[3] and is where the butterfly gets its distasteful toxins that protect the butterfly from predation.[1] The caterpillar may eat all of the leaves on a plant, but they then grow back.[1]
All parts of this plant are toxic to humans.[1] [4]
It is found from Arizona to western Texas, in mountains at elevations from 2000to.[2]
Native Americans believed it could be used to treat snakebites, hence its common names Indian root or snakeroot.[2] It is currently found in some nurseries that feature native plants as it is a good landscape plant in a butterfly garden.[5]