OF NORTH AIHEKICA. 41 



swelled obliqual reticulate or squamose. 3 sp. 

 Ahelicea cretica, sibirica, and aquatica our 

 own, 



573. PLEUROSTENA Raf. fl, tel. 413. 

 Calix rhomboidal 5fid unequal. Stamens 5 

 subequal, stigmas 3 sessile. Seed conical lon- 

 ger than calix, unequal trigone, one side nar- 

 rower. Floicers axillary polygamous. One 

 of the 20 Genera blended in Polygonum, re- 

 vised by me in fl. tel. The type of this is a 

 small western shrub. The name means nar- 

 row side. 



574. Pleurostena serotina Raf. Polyg. do 

 Raf. An nat. 93. Suffruticose, stem striate 

 much branched, branches angular virgate, 

 leaves nearly sessile ovatoblong acute smooth, 

 sheaths split lacerated, flowers axillary fasci- 

 culate — discovered and published in 1820, a 

 small shrub 2 or 3 feet high woody only at the 

 base^ quite autumnal blossoming late in Octo- 

 ber, growing in fields and glades in Kentucky. 

 Leaves quite small, flowers green 2 to 5 to- 

 gether on short peduncles, often polygamous 

 by the abortion of stamens. Different from 

 Stopinaca fl. tel. 405 or Polygonella of Mx. 

 which I have also. 



575. SPERMAULAXEN Raf. fl. tel. 416. 

 Monoical, male fl. campan. 4-5fid, segments 

 subequal obtuse colorate. Stam 4-5 very short, 

 female fl. similar larger more unequal, seg- 

 ments erect obovate, stigmas 2-3sessile. Seed 

 pyramidal double of calix trigone, base con- 

 crete, one side concave canaliculate. Shrub- 

 by fl, spiked — another very distinct G. of same 

 tribe akin to the last, to which perhaps belong 

 also the exotic sp. blended as Polyg. ochreatum 



6 



