26 American Midland Naturalist Monograph No. 7 



Section 10. Plants Twining or Climbing; or Cacti 



1. Cactus plants, with conspicuously jointed stems, the internodes flattened, 

 succulent, bristly or spiny; leaves none, or reduced to bristles; flowers 

 perfect, regular, solitary, showy ; sepals, petals, and stamens numerous 



79. Cactaceae 



1. Not cactus plants; stems twining or climbing; plants sometimes with tendrils. 

 2. Plants with tendrils. 

 3. Leaves entire. 



4. Flowers in umbels; perianth 6-parted; stamens 6; stigmas thick, 

 almost sessile; fruit a berry; leaves with 3 or more principal veins 

 from the base Smilax in 130. Liliaceae 



4. Flowers in slender axillary and terminal racemes; calyx 5-parted; 



stamens 8 ; styles 3 ; fruit an obtusely triangular achene enclosed in 



the indurated calyx; leaves with 1 main vein 



Brunnichia in 32. Polygonaceae 



3. Leaves lobed or toothed, or compound. 



5. Flowers solitary, perfect; petals separate; stipules present 



78. Passifloraceae 



5. Flowers unisexual, in racemes or corymbs. 



6. Petals united; fruit a pepo 81. Cucurbitaceae 



6. Petals separate; fruit an inflated capsule 45. Sapindaceae 



2. Plants without tendrils. 



7. Leaves somewhat peltate, the petiole attached on the underside of the 

 blade near the margin, the blades usually angled or lobed; fruit 



juicy, 1-seeded; flowers small, in axillary panicles 



10. Menispermaceae 



7. Leaves not peltate. 



8. Leaves opposite or whorled. 

 9. Leaves entire. 



10. Plants with milky juice: petals 5, united; fruit a follicle; seeds 

 with silky hairs. 

 11. Stamens distinct; flowers cymose 99. Apocynaceae 



11. Filaments united into a tube enclosing the pistil, the an- 



thers adnate to the stigma, and the pollen cohering in 



masses 100. Asclepiadaceae 



10. Plants without milky juice. 



12. Sepals 4, petal-like; petals 0; stamens numerous; style per- 



sistent on the achene, often pubescent 



Clematis in 3. Ranu.nculaceae 



12. Flowers otherwise. 



13. Perianth 6-parted; stamens 6; plants dioecious; fruit a 



3-angled capsule 137. Dioscoreaceae 



13. Sepals 5; petals 5; stamens 5; flowers perfect; fruit a 



follicle; seeds with a tuft of hairs 



Ampelamus in 100. Asclepiadaceae 



9. Leaves toothed or lobed. 



14. Leaves triangular-hastate; flowers pink, in small heads 



Mikania in 125. Compositae 



14. Leaves not triangular-hastate; flowers green, unisexual, in cat- 

 kins or panicles 72. Cannabinaceae 



8. Leaves alternate, or reduced to inconspicuous scales. 



15. Plants with chlorophyll, not parasitic; leaves not reduced to 

 scales. 



