30 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. IV. 



to be strongly cleft or 2-valved (sometimes more or less malformed), 1 

 and in various other characters are too close to admit of any taxonomic 

 separation. 



The specimens collected by Deane in Massachusetts have the nu- 

 merous burs identical with those on Piper's plant from Washington, 

 but the leaves differ noticeably in being sharply lobed and dentate. 

 Our knowledge of the genus, however, convinces us that the foliage 

 characters are entirely too unstable to warrant satisfactory segregation 

 of forms when unaccompanied by definite characters of the fruits. 

 Hence we must refer the Massachusetts plants to this species. 



10. Xanthium cenchroides, sp. nov. 



Caulis longitudinaliter plus minusve purpureo-maculatus, supra 

 subscabridus. Folia non crassa, dentata, supra scabrida, infra scabra et 

 minute reticulata. Fructus (PI. VII, f. 10; PL VIII, ff. 37-39) ovati, 

 superne in duo rostra producti; exteriore facie glanduloso-hispida et 

 circum 25 aculeis armata; corpore (rostris non adjectis) 1.5-1.7 cm. 

 longo et 6-7 mm. lato; rostris arcuatis, infra hispidis, supra glabratis 

 et ad apicem hamosis, circum 8 mm. longis; aculeis rectis aut subrectis, 

 infra hispidis, supra glabris et ad apicem hamosis, 8-10 mm. longis. 



DISTRIBUTION : Texas. 



SPECIMENS EXAMINED: TEXAS: near Ferris, J. Reverchon 2332 

 (type in Hb. Mo. 85563; additional material, ibid., on sheet no. 85564). 



The type material is very fragmentary, the leaves nearly all having 

 been destroyed by worms. The fruiting burs, however, are present in 

 fair quantity and are very distinct from those of any other Xanthium 

 known to us. In their small number of prickles, the burs resemble those 

 of X. Wootoni Cockll., but in size of body, length of prickles etc., there 

 are very pronounced differences. The burs suggest very strongly the 

 fruiting involucres of Cenchrus carolinianus Walt., although of course 

 much larger. 



11. XANTHIUM INFLEXUM Mack, and Bush, Rept. Missouri Bot. Gard. 



16: 106. 1905. 



Caulis glabratus aut superne setulis albis plus minusve scabridus, 

 ramosus, 11.5 m. altus. Folia cordata aut ovato-cordata, tri-aut sub- 

 quinquelobata, irregulariter serrata aut dentata, infirme aut valide 

 scabrida, petiolis adjectis 0.8-2.5 dm. longa, petiolis laminis subaequan- 

 tibus. Fructuum (PL VII, f. n; PL IX, ff. 1-4) corpus oblongo-ellip- 

 ticum aut ovato-oblongum, exteriore facie non paucis aculeis armatum, 

 aliter glabrum aut sparsim glandulosum, 1.3-1.7 (-2) cm. longum et 

 6-7.5 rnm. crassum; rostris validis, maturis ad medium abrupte flexis, 

 valde incurvatis, ad apicem hamosis, saepe mutuo contingentibus, infra 



1 The specimen collected by Piper has several burs with the achenes protruding 

 at the top. 



