AKISTOLOCHIACE.^. (bIRTHWOKT FAMILY.) 391 



bracts shorter than the flower ; lobes of the corolla rounded ; capsule 2-seeded. 



— Nashville, Tennessee (Gattinger), and westward. 



Var. aristata, Gray. Leaves linear-lanceolate ; spike linear, the filiform 

 bracts 3-6 times the length of the flower. — Waste ground, Georgia, and 

 westward. — Scape 1° or less high. 



5. P. lanceolata, L. Smooth or pubescent ; leaves lanceolate, acute, 

 denticulate, 3 - 5-ribbed, loug-petioled ; spikes dense, ovate or oblong ; capsule 

 2-seeded. — Pastures and waste ground. Introduced. — Scape 1°- 2° high. 

 Spikes V-2' long. 



6. P. sparsiflora, Micli.x. Leaves smooth, lanceolate, toothed or en- 

 tire, narrowed into a long petiole ; scape much longer than the leaves, pubes- 

 cent below; spike long, loosely flowered ; bracts ovate; calyx lobes obtuse; 

 capsule 2-seeded. — Moist pine barrens, Georgia and South Carolina. June - 

 Sept. — Spikes 6'- 9' long. 



* * Flowers dicecious : annuals. 



7. P. Virginica, L. Pubescent ; leaves lanceolate or oblong, toothed 

 or entire, 3 - .5-ribbed, on rather short petioles ; spike cylindrical, densely 

 flowered ; stamens 4 ; capsule 2 - 4-seeded. — Low sandy soil, very common. 

 April -June. — Scape 1' (and then 2-4-flowered)-l° high. Leaves -J^'-G' 

 long. 



8. P. heterophylla, Nutt. Smooth or pubescent ; leaves somewhat 

 fleshy, linear, entire, or with scattered spreading teeth; spikes linear, closely 

 flowered ; the lower flowers scattered ; stamens 2, exserted ; capsule many- 

 seeded, twice the length of the calyx. — Waste places and fields. April - 

 May. — Scape 2' -6' high, commonly longer than the leaves. 



9. P. pusilla, Nutt. Small (r-2' high), slightly pubescent; leaves 

 narrow-linear, entire ; capsule ovoid, rather longer than the calyx, 4-seeded. 



— Tennessee, and northward. 



Division IIL APETALOUS EXOGENOUS PLANTS. 



Floral envelopes single, consisting of a calyx only, or 

 altogether wanting. 



Order 104. ARISTOLOCHIACE^. (Birthwort Family.) 



Herbs or woody vines, with alternate petioled mostly cordate and 

 entire leaves, and solitary peduncled dull-colored flowers. — Calyx ad- 

 herent to the 5 - 6-celled ovary, tubular, valvate in the bud. Stamens 

 5-12, more or less united with the styles: anthers adnate, extrorse. 

 Fruit 5 -6-celled, few - many-seeded. Seed anatropous. Embryo 

 minute, at the base of fleshy albumen. 



1. ASARUM, Tourn. Asarabacca. 



Calyx regular, 3-lobed. Stamens 12, the filaments partly united with the 

 style, and usually prolonged beyond the anthers. Capsule fleshy, globose, 



