o8l 
+ + Valves very prominently toothed. 
10. R. obtusifolius L. Erect,6to9dm. high: stem usually and sometimes strongly 
papillate: leaves somewhat undulate, ample or the lowest very large, broadly ovate, 
cordate, frequently acute, the often purple veins papillate, especially beneath: 
flowering branches suberect, sparingly leafy below: lower whorls loose and rather 
remote; pedicels slender, about twice as long as the fruit, swollen-jointed toward 
the base: valves flexible, not very heavily veined, 2 to 3 by 4 to 5 mm, ovate-oblong, 
with 3to 5 thin triangular teeth on each side; callosities smooth, ovoid, scarcely 
reaching the middle of the valve, the largest one about Lim, broad, the other two 
usually very small: achene 1.3 by 2.2 mn.—Introduced every where in the east, and 
extending into Texas. 
PODOSTEMACER. (RIVER-WEED FAMILY.) 
Aquatics, growing on stones in running water, some with the aspect 
of sea-weeds, others of mosses or liverworts, with minute naked flowers 
bursting from a spathe-like involucre and producing a 2 or 3-celled 
many-seeded ribbed pod. 
1. PODOSTEMON Michx. 
Submerged plants with 2-ranked leaves, n sarly sessile solitary flowers, 
2 stamens (with 2-celled anthers) borne on the side of the stalk of the 
ovary with their long filaments united for more than half their length, 
® short sterile filaments (one on each side), 2 subulate stigmas, 8-ribbed 
9-celled 2-valved pedicellate pod, and very many minute seeds on a 
thick central placenta. 
1. P.ceratopnyllus Michx. A small olive-green plant of firm texture, resembling 
a seaweed, attached by fleshy disks: leaves rigid or horiy, dilated into a sheathing 
base, mostly forked into filiform linear lobes.—-Not rare in shallow waters, extend- 
ing into eastern Texas from the Atlantic States. 
ARISTOLOCHIEH. (Birrawort FAMILY.) 
Twining shrubs or low herbs, with petiolate mostly cordate entire 
leaves, pertect tlowers, conspicuous lurid calyx valvate in the bud and 
coherent (at least at base) with the 5 or 6-celled ovary which forms a 
many-seeded 5 or G-eelled pod or berry in fruit, 5 stamens more or 
less united with the style, and adnate extrorse anthers. 
1. ARISTOLOCHIA L. (Birruworrt.) 
Perennial herbaceous or frutescent somewhat climbing plants, with 
alternate leaves, solitary axillary flowers, unilabiate calyx-limb, 5 
stamens (the sessile anthers wholly adnate to the short and fleshy 
5-lobed or angled style), a 5-celled pod, and very flat seeds. 
1. A. brevipes Benth. Suifruticose, low, hirsute pubescent: stem branching 
from the base, with simple slender and diffuse branches: leaves small, reniform- 
cordate or subhastate-cordate, very obtuse, with rounded divergent auricles and 
short petioles: flowers small, short-peduneculate; bracts cordate: calyx-tube broadly 
arcuate, the limb lanceolate and obtuse: seed obcordate, punetate.—Chenate moun- 
tains; rare. 
