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Aristolochia watsonii (Watson's Dutchman's pipe, southwestern pipevine, Indian root, snakeroot) is a perennial plant in the birthwort family (Aristolochiaceae), found growing among plants of the Arizona Uplands in the Sonoran Desert.:138 The plant is inconspicuous,:138 small and hard to spot, but can be found by following the pipevine swallowtail (blue swallowtail, Battus philenor) which lays eggs on it.
Roots, stems, and leaves
According to one source, stems are 6 to 18 inches (15 to 46 cm) long, with greenish-brown arrowhead shaped 1⁄4 to 2 1⁄2 inches (0.64 to 6.35 cm) leaves.:138 Another source states stems can reach 3 feet (0.91 m), in dense mats that are 1 to 2 feet (0.30 to 0.61 m) wide. It drops its leaves in the fall and winter (cold-deciduous), and losing stems as well as leaves in a freeze. In full sun and drought conditions, leaves turn from green to purple-brown.
Inflorescence and fruit
It has "bizarre" looking, musky smelling flowers, which resemble the ear of a rodent.:138 It blooms from April to October. 1 to 1 1⁄2 inches (2.5 to 3.8 cm) flowers are shaped like a rodent's ear:138 are green or burgundy-brown outside to the ear rim, then green speckled with burgundy-brown inside, with hairs on the opening ear rim.:138 Flowers last 1–2 days.
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.:138 It attracts the Pipevine Swallowtail, and is where the butterfly gets its distasteful toxins that protect the butterfly from predation. The caterpillar may eat all of the leaves on a plant, but they then grow back.
Habitat and range
- "Aristolochia watsonii Wooton & Standl.". The Plant List. Royal Botanic Gardens, Kew and Missouri Botanical Garden. Retrieved 28 August 2014.
- Aristolochia watsonii: Watson's Dutchman's Pipe / Desert Pipevine, Garden Oracle, Gardening in Tucson, Phoenix, and the Desert Southwest, 
- Sonoran Desert Wildflowers, Richard Spellenberg, 2nd ed., 2012, ISBN 9780762773688
- Naturewide Images, Robert A. Behrstock, ATTRACTING WILDLIFE I
- Pipevine Swallowtail, Battus philenor, Fairfax County Public Schools