AMMIACEAE. 



Vol. IL. 



I. Oxypolis filiformis (Walt.) Britton. 

 U.xypolis. Fig. 3130. 



Oenaiilhe filiformis Walt. Fl. Cai. 113. 1788. 

 Ocnaiithe teretifolia Mulil. Cat. 31. 1813. 



Tiedcmatutia tcrclifolia DC Mem. Omb. 51. pi. /.. 1829, 



Oxyfolis filiformis Britton, Mem. Torr. Club 5 : 239. 1894. . 



Stem hollow, 2-6 high. Leaves reduced to linear 

 hollow usually jointed acute phyllodia l'-i8' long^ 

 involucre of several linear-subulate bracts; umbels 

 2-4' broad, 6-iS-rayed; rays slender, i'-2' long; 

 pedicels 2"-4" long; fruit oval, 01 slightly obovate, 

 2"-3" long; oil-tubes large. 



In ponds and swamps, southern Virginia to Florida, 

 west to Louisiana. Aug.-Sept. Plants collected in Dela- 

 ware, referred to this species, differ in having broadly 

 oval corky-winged fruit, an inconspicuous disk, slender 

 conic stylopodium and smaller oil-tubes. Water-dropwort.- 



2. Oxypolis rigidius (L.j Raf. Cow- 

 bane ' liemlucl-; or Water Dropwort. 

 Fig- 3131- 



Slum rigidius L. Sp. PI. 251. 1753. 



O. rigida Raf.: Scr. Bull. Bot. 218. 1830. 



O. hiigifolius Britton, Mem. Torr. Club 5 : 239 



1894. 

 Slum longifolium Pursh, Fl. Am. Sept. 194. 1S14. 



Rather slender, 2-6 high. Leaves simply 

 pinnate, the lower often i long or more; 

 leaflets thick, ovate-lanceolate, lanceolate-linear 

 or oblong, entire, or remotely dentate, 1V-3 

 long, 3"-i2" wide; umbels 2'-4' broad, 7-25- 

 rayed; rays slender, i'-4' long; pedicels 2"-9" 

 long; fruit oval, 2i"-3" long, iV'-2" broad; 

 oil-tubes small. 



In swamps, New York to Florida, Minnesota, 

 Missouri and Louisiana. Aug.-Sept. Pig-potato. 



21. IMPERATORIA [Tourn.] L. Sp. PI. 259. 1753. 



Tall perennial herbs, with large ternately divided or 2-pinnate leaves, sheathing petioles,, 

 and compound umbels of white flowers. Calyx-teeth obsolete. Petals ovate, mostly emar- 

 ginate. Fruit much flattened dorsally, broadly oval, to nearly orbicular, cordate at both ends, 

 the lateral ribs broadly winged all around, the intermediate and dorsal ribs slender, wingless; 

 oil-tubes solitary in the intervals and 2 on the commissural side. Styles and conic stylo- 

 podium short. Seed-face Art. [Named for its supposed forceful medicinal properties.] 



About 10 species, natives of the Old World, the following typical. 



I. Imperatoria Ostriithium L. ]\Iaster- 

 wort. Pellitory of Spain. Fig. 3132. 



Imperatoria Oslrulhium L. Sp. PI. 259. 1753. 



Glabrous, or sparingly pubescent : stem stout, 

 hollow, erect, 2-$ tall. Leaves ternately divided 

 into very broad stalked ovate to obovate seg- 

 ments, which are often 3-parted nearly or quite 

 to, the base, sharply and unequally serrate and 

 often incised, the segments of the long-petioled 

 lower leaves often 5' broad; rays of the umbels 

 and pedicels very numerous, slender ; involucre 

 none, or of i or 2 lanceolate bracts; involucel- 

 bracts few, narrow, deciduous ; fruit broadly oval, 

 about 2" long. 



In fields, Pocono plateau of Pennsylvania, and 

 Michigan. Reported from Newfoundland. Natu- 

 ralized or adven'ti\'e from Europe. Broad-leaved 

 hog's-fennel. Felon-grass. Imperial masterwort. Fel- 

 onwort. May-July. 



