APRIL, 1918. XANTHIUM AND SOLIDAGO MILLSPAUGH & SHERFF. 3 



Mus. cat. no. 430064); Dr. Arthur Schott, near Georgetown, D. C., 

 Sept. 6, 1863 (Herb. Field Mus. cat. no. 44074); /. M. Greenman 538, 

 along the river near Tygart Junction, Barbour Co., W. Va., Sept. 24, 

 1904 (Herb. Field Mus. cat. no. 345709); A. S. Hitchcock, Key West, 

 Fla., Mar. 28-30, 1906 (Herb. Field Mus. cat. no. 230307); anonymus, 

 Lake City, Fla. (Herb. Fla. Agri. Coll. no. 1279, Herb. Field Mus. cat. 

 no. 234909); Royal A. Diocon 40, Huntsville, Texas, June 3-12, 1908 

 (Herb. Field Mus. cat. no. 237976). 



A study of the specimens in the above list shows X. americanum 

 to have for its fruiting involucre a bur distinctly ovoid in shape, 1.2-1.5 

 cm. long (exclusive of the beaks), the beaks straight or nearly so, and 

 the entire body tending to be, aside from its prickles, more or less 

 glabrous; the prickles are straight from the base almost to the apex, 

 where they are usually hooked. On comparison with these specimens, 

 we find three sheets of material that show striking departures in certain 

 directions, and a fourth bearing material that is more properly com- 

 parable with X. pennsylvanicum Wallr., from which it differs, however, 

 in several important respects. As all four of these specimens are com- 

 pletely irreconcilable with any form of Xanthium known to us, they 

 are described herewith as representing new species: 



Xanthium leptocarpum Millspaugh & SherfE sp. nov. PL I, & Vff. i & 5. 



Herba annua, 3-5 dm. alta; caule inermi, superne scabro. Folia 

 alterna, circumambitu plus minusve deltoidea et trilobata, margine 

 dentata, basi triplinervia et cordata aut subtruncata, utrimque setulis 

 adpressis vestita, infra sed non supra minute reticulata, petiolata, 

 petiolis adjectis 7-19 cm. longa, petiolis tenuibus et laminis subae- 

 quantibus. Fructus multi, 4-12 simul congregati, anguste cylindrico- 

 fusiformi, badii, superne sensim angustati et in duo rostra arcuata 

 distantia producti, exteriore facie 18-40 aculeis (2-3 aut rare-4 mm. 

 longis) armati, pubescentes et numerosis punctis resinae punctati uti 

 bases aculeorum et rostrorum; rostris et aculeis ad apicem hamosis, 

 rostris crassioribus et paulo longioribus; fructus corpore (rostris non 

 adjectis) 1.3-1.6 cm. longo, 3.5-5 mm. crasso. Achaenia 2 ; maiore circum 

 1.8 cm. longo et 4 mm. lato, 3-costato, levi, base acuminate, rostro 

 abrupte mucronulato. 



L. R. Jones, Burlington, Vermont, September 12, 1896 (type in 

 Herb. Field Museum, cat. no. 430860). 



This species is very distinct in the appearance of its fruiting in- 

 volucres. These have a reddish-brown or chestnut color and are nar- 

 rowly cylindric-fusiform, not ovoid. The prickles are very few in 

 number (18-40) and noticeably far apart. 



