Aristolochia L.

2. Aristolochia L. View in CoL 1

Perennial herbs or woody climbers. Flowers axillary. Perianth zygomorphic, deciduous, the base swollen (utricle), the upper part narrower, more or less cylindrical (tube); limb unilateral and entire, rarely absent or 3-lobed. Stamens usually 6, in 1 whorl, connate with stylar column. Fruit a septicidal capsule.

A. durior Hill , Veg. Syst. 21: 57 (1772) ( A. sipho L’Hér. ) from North America is commonly cultivated for ornament, and may sometimes occur partly naturalized. It is a woody climber with leaves up to 30 cm and the perianth brownish with a 3-lobed limb.

Literature: P. H. Davis & M. S. Khan, Notes Roy. Bot. Gard.

Edinb. 23: 515-46 (1961).

1 Flowers 2 or more together in the axil of a leaf 6. clematitis

1 Flowers solitary

2 Stem usually climbing, woody; leaves evergreen, coriaceous

3 Ovary and pedicels pubescent 1. sempervirens

3 Ovary and pedicels glabrous 2. baetica

2 Stem not climbing, herbaceous; leaves not coriaceous

4 Perianth without conspicuous unilateral limb, the apex davate, with a small pore 13. microstoma

4 Perianthwithlarge conspicuous unilaterallimbat least£ as long as tube

5 Perianth-tube strongly curved, 10-20 mm in diameter; utricle oblong-cylindrical

6 Leaves not more than 5-5 x 6 cm; limb of perianth with auricles 2-5 mm long at base 3. eretica

6 Leaves up to 16 x 15 cm; limb of perianth with auricles up to 20 mm long at base

7 Leaves ovate-orbicular, cordate to reniform, about as long as wide 4. pontica 7 Leaves ± deflate to ovate-cordate, distinctly longer than wide 5. bodamae

5 Perianth-tube ± straight, less than 5 mm in diameter; utricle ± globose

8 Leaves with cartilaginous teeth or papillae on the margin and lower surface; tubers numerous, fasciculate, cylindrical 7. pistolochia

8 Leaves without cartilaginous teeth or papillae (rarely with the margin undulate or spinulose); tuber solitary, globose or cylindrical

9 Leaves ovate-orbicular, ± sessile, amplexicaul; flowers yellow, with dark brown limb 8. rotunda

9 Leaves petiolate, not amplexicaul 10 Leaves not more than 2(—3) x 1(—1-5) cm, ovate-oblong to ±triangular; flowers 1-3 cm, brownish-yellow,

with brown stripes and reddish limb 12. bianorii

10 Largest leaves at least 2 x 2 cm, ovate-triangular to ovate-reniform; flowers at least 2 cm, brownishgreen to pale yellow, with purplish or brownish stripes

11 Petiole 25 mm or more; leaves acute to acuminate

10. sicula

11 Petiole not more than 25 mm; leaves obtuse to subacute

12 Tuber globose; flowers green, yellow or pale brown,

with purplish or brownish stripes, the limb often darker 9. pallida

12 Tuber cylindrical; flowers brownish-green, the limb brownish-purple 11. longa