86 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
more or less imbedded in the seed and adhering to it, 2 on the com- 
missural side, Seed face plane or somewhat concave. 
Glabrous annuals, with thin pinnately decompound leaves and linear 
segments, lateral few-rayed umbels opposite the leaves, involucre and 
involucels of few linear entire or divided bracts, and white flowers. 
A monotypic genus belonging to the southern prairie region of the 
United States. 
1. Trepocarpus aethusae Nutt. in DC. Coll. Mém. 5: 56. pl. 14. 1829. 
Fia. 18. 
From 1 to 9 dm. high; umbels 2 to 5-rayed; umbellets few-flowered, 
with very short pedicels; fruit 8 to LO mm, long. 
Type locality, ‘* territoire d’Arkansa”; collected by Vuétall, type 
in Herb. DC., duplicate in Herb. Philad. Acad. 
Prairies of Arkansas and Indian Territory to Alabama and Texas. 
Specimens examined: 
Arkansas: Fort Smith, Bigelow, in 1853-54; near Little Rock, Coville 25, July 8, 
1887; same station, Mrs. Tu/t, in 1888. 
InpIAN TeRRITORY: Sans Bois Mountains, Sheldon 101, July 6, 1891. 
ALABAMA: Near Mobile, Mohr. 
Mississippr: Starkville, Phares, May, 1885. 
Texas: Hempstead, all 258, June 10, 1872; near Dallas, Reverchon, June, 1879, 
1880, and 1881; Thurow, in 1889. 
20. APIUM L. Sp. Pl. 1: 264. 1758. 
Calyx teeth obsolete. Fruit flattened laterally, ovate or broader 
than long, glabrous. Carpel with prominent obtuse nearly equal 
corky ribs and no strengthening cells. 
Stylopodium wanting or depressed. Oil 
tubes solitary in the intervals, 2 on the 
commissural side. Seed section round. 
b Erect or prostrate glabrous herbs with 
pinnately or ternately divided leaves and 
umbels of white flowers opposite the leaves. 
Kirst species cited is A. petroselinwm Li, 
which isa Petroselinum, the second species cited is A. graveolens L. 
A group of about 20 species chiefly dispersed through the Eastern 
Hemisphere and represented in our native flora by a single widely 
distributed species. 
1. Apium ammi (L.) Urban, FL Bras. 11': 341. pl. 91. 1879. 
Fic. 19. 
Sison ammi L. Sp. Pl. 1: 252. 1753; Jaeq. Hort. Vindob, 2: 95, pl. 200. 1772. 
A, leptophyllum F. Muell. in Benth. Fl. Austral. 3: 3872. 1866. 
Fria. 19.—Apium ammi: 
a, ~ 10; b, x 12. 
From 1 to 6 dm. high; leaves ternately divided into filiform seg- 
ments; umbels sessile or short pedunculate; fruit 2 mm. long. 
Type locality, ‘tin Apulia, Aigypto.” 
In wet ground from North Carolina to Florida, westward to Texas 
and California; also extending into Mexico and South America. 
