Greene — Revision of the Genus Wislizenia. 129 



Valves pyriform, neither obviously lineolate nor at all 



tuberculate, usually quite smooth. 2. W. melilotoides. 



Valves sliorter, obovoid, with few low ribs, an obscure reti- 

 culation, and a few low tubercles at summit. 



3. W. Californica. 

 Valves pyriform, closely and sharply lineolate, and with 



a crown of more prominent but low tubercles. 



4. W. divaricata. 

 Valves round-ol)ovoiil, with 5 prominent ribs and some 



reticulation, the summit with a few low tubercles. 



5. W. pacalis. 

 Valves short, almost subcylindric, prominently both 

 ribbed and reticulate and with a low tuberculation. 



6. W. scabrida. 

 Valves mostly subpyriform, but summit less rounded, usually quite trun- 

 cate, in most species conspicuously mamillate-tuberculate. 



Valves pyriform, closely and sharply lineolate and with 

 some elongated reticulation, the summit crowned 

 with a circle of 5 spreading mammiform tubercles. 



7. W. fruticosa. 

 Valves long, subturbinate-pyriform, strongly striate, near 



the summit fenestrate-reticulate, the summit with a 



circle of long connivent tubercles. 8. W. Palmeri. 



Valves short subquadrate-obovate, the lower half strongly 

 ribbed and closely striate, the broad summit traversed 

 by a few elevated ridges. 9. W. costellata. 



Valves subturbinate above a short cylindric base, the whole 

 ribbed and lineolate, hardly reticulate, the summit 

 with large mammiform tubercles. 10. W. mamillata. 



1. Wislizenia refracta Engelm. 



Widhenia refracta, Engelm. Wisliz. Mem. 99. 



, Gray, PL Wright. 1. 11, t. 2. 



, Gray, Syn. Fl. 1. 186 in part. 



Tall and rather lax not stout glabrous annual : leaflets elliptic or oblong- 

 elliptic, acute at both ends, mostly 2.5-3 cm. long ; fruiting racemes slender, 

 5-10 cm. long: carpels pyriform, marked with a few low ribs or striae and 

 much intervening reticulation, especially toward the rounded summit, this 

 part sometimes with a few low tubercles by no means conspicuous. 



Originally from the valley of the Rio Grande about El Paso, Texas, and 

 in adjacent New ]\Iexico; and no specimens yet seen from more westerly 

 stations, to which it might be expected to migrate after the advent of the 

 railways, and where it may yet be found; but, I apprehend, only as a 

 migrant; all western plants at present known exhibiting characters as 

 distinct. 



