POLYPETALOUS EXOGENOUS PLANTS. 195 



fertile plant, and elliptical, obtuse, or emarginate on the 

 sterile, slightly crenulate, and like the cymose panicle 

 stellate-pubescent ; stamens 4-5 ; carpels 1-2, obovate, stipu- 

 late ; seed solitary, obovate, black and shining. Leaves l'-2' 

 long. Cyme sessile, divided into three primary branches. 

 Flowers minute. 



Z. Pie ROTA. Branches zigzag, armed with short curved 

 prickles ; 2^etiole winged, jointed ; leaflets 7-9, small, obo- 

 vate, coriaceous, crenate above the middle, sessile ; flowers 

 in axillary clusters, which are single or by pairs, as long 

 as the first joint of the petiole; stamens ^\ ovaries 2; car- 

 pels solitary, globose, pitted, distinctly stipitate ; leaflets 

 J'-J' long, those on the fertile plant narrower and smaller ; 

 carjjels small, dotted. 



Z. HiRSUTUM, Buckley. Young branches and peti- 

 oles prickly and strongly hirsute; leaves pinnate, 

 2-3-paired ; leaflets ovate - lanceolate, crenate, obtuse ; 

 flowers axillary or terminal, shortly paniculate; carjyels 

 subcordate, 1-2-seeded ; seeds subovate. — Tree about 25 

 feet high, and 8-12 inches in diameter ; branches armed 

 with stout recurved prickles ; leaflets opposite or sub- 

 alternate ; trunk and old branches gray and smooth. 

 Near Corpus Christi. 



PTELEA, L. Hop Tree. 



Floioers polygamous ; sepals and petals 4-5, imbricated 

 in the bud, deciduous ; stamens 4-5 ; ovanj 2-celled, 

 with two ovules in each cell ; style short ; stigma 2-lobed ; 

 capsule 2-celled, 2-seeded, surrounded by a broad, circular, 

 reticulated Aving. — Unarmed shrubs, witli trifoliate leaves, 

 and small greenish /o^^^ers in a terminal cijme. 



P. TRiFOLiATA. Pubesceut ; leaves long-petioled; leaf- 

 lets oval or oblong, mostly acute, obscurely crenulate, 

 paler beneath, the lateral ones unequal-sided ; filaments 



