Aristolochia Linnaeus 1753

Key to the species of Aristolochia from Laos 1. Perianth strongly curved; utricle slightly differentiated; tube U- or horseshoe shaped (in side view); gynostemium 3-lobed........................................................................................................................................................................................ 2 (subgen. Siphisia) - Perianth straight or slightly curved; utricle well-developed; tube rectilinear or slightly curved (in side view); gynostemium 6- lobed..............................................................................................................................................................4 (subgen. Aristolochia) 2. Limb cylindric or saccate-shaped …............................................................................................................................... 1. A. laotica - Limb trumpet-shaped, or discoid or nearly so................................................................................................................................... 3 3. Leaf lamina broadly ovate to cordate. Cymes 3–4-flowered, formed in old woody stems, in clusters of 6–8(–10); limb trumpetshaped….............................................................................................................................................................. 2. A. faviogonzalezii - Leaf lamina narrowly elliptic to lanceolate-elliptic. Cymes 1–2-flowered, axillary, solitary or paired; limb discoid or nearly so.......................................................................................................................................................................................... 3. A. versicolor 4. Leaves deeply 3-lobed.....................................................................................................................................................4. A. pothieri - Leaves entire.......................................................................................................................................................................................5 5. Stems zigzag. Petiole less than 0.5 cm long......................................................................................................... 5. A. harmandiana - Stems not zigzag. Petiole more than 1 cm long.................................................................................................................................6 6. Leaf base cuneate. Seeds not winged................................................................................................................................ 6. A. indica - Leaf base slightly to deeply cordate. Seed winged.............................................................................................................................7 7. Leaf blade broadly ovate, twice as long as broad, glabrous on both sides. Seeds warty on one side....................... 7. A. acuminata - Leaf blade narrowly oblong-lanceolate, three-four times longer than broad; puberulous on abaxial leaf surface. Seeds warty on both sides.......................................................................................................................................................................... 8. A. pierrei
Published as part of Do, Truong Van, Hoang, Thao Thi, Wen, Fang, Wanke, Stefan, Forbes, Malcolm & Souladeth, Phetlasy, 2023, Aristolochia laotica (subgen. Siphisia), a new species from Northeastern Laos, pp. 155-163 in Phytotaxa 591 (2) on page 161, DOI: 10.11646/phytotaxa.591.2.7, http://zenodo.org/record/7797540