PLANTS OF SOUTHERN: NEW JERSEY. 519 



ZANTHOXYLUM L. 

 Zanthoxylum americanum Mill. Prickly Ash. 



Zantholoxylum americanum Miller, Gard. Diet. Ed. 8. No. 2. 1768 [South 



Carolina]. 

 Xanthoxylon America,niini Britten 74.— Keller and Brown 209. 



Locally common in the northern counties, but very rare in 

 our region; reported but once within our limits — Freehold, on 

 authority of Willis. 



PTELEA L. 

 Ptelea trifoliata L. Three-leaved Hop Tree. 



Ptelea trifoliata Linnaeus, Sp. PI. 118. 1753 [Virginia].— Britton 74. 



Woodlands in the Delaware Valley; rare. Found on Ridge's 

 Island, Hunterdon County, and on the banks of Crosswick's 

 Creek, both in Mercer County, by C. C. Abbott (Britton's 

 Catalogue) and Burlington by A. C. Apgar, who collected a speci- 

 men near Bordentown, which is now in the N. J. Geological 

 Survey herbariumi at New Brunswick. This tree has almost 

 precisely the samle distribution as the Judas, both of them south- 

 ern species, which find their northern limit in these river valleys, 

 but which cannot establish themselves below the head of tide- 

 water, probably on account of the lack of steep, wooded banks. 



Fl. — Late May to mid-June. Fr. — September to October. 



Middle District. — Bordentown (NB). 



Famiily POLYGAiLACE^. Milkworts. 



Key to the Species, 

 a. Flowers in spikes or spike-like racemes at the summit of the stem or its 

 branches. 

 b. Basal leaves spatulate, flowers orange yellow. Polygala lutea, p. 520 

 bh. Basal leaves inconspicuous or wanting, flowers not yellow. 

 c. Leaves, some at least verticillate. 

 d. Spikes 4-6 mm. thick. 



e. Most of the leaves in whorls, flowers greenish white. 



P. verticillata, p. 522 

 ee. Most of the leaves alternate, only the lowest in whorls, 

 flowers usually slightly pink tinted. P. ambigua, p. 522 



dd. Spikes 8-18 mm. thick. 



e. Spikes sessile or nearly so, wings deltoid, flowers purple 



or greenish white. P. cruciata, p. 521 



ee. Spikes peduncled, leaves less regularly verticillate, wings 



lanceolate ovate, flowers purple. P. brevifolia, p. S21 



cc. Leaves all alternate. 



