FLORA OF WASHINGTON AND VICINITY. 109 



Rumex verticillatus, L. 



Above Sandy Laudiug. Juue, July. 



t Rumex c?-ispu8, L. Curled Dock. 

 Juue. 



t Rumex ohtusifolius, L. Bitter Dock. 

 May to July. 



Rumex crispuaxobtusifolius, Gray, Manual, ed. 5, p. 421. 



This well-marked hybrid is this year abundant in the city reservation west of the 

 Capitol, between Four-and-a-half and Sixth streets, where it may be easily com- 

 pared with l)oth the parent species. It may be roughly described as having the nar- 

 row leaves of li. crisjJMS, though less wavy-margined, and the toothed valves of B. 

 obtusifoUus, this character being, however, less evident on the uon-grain-beariug 

 valves. The habit of the hybrid is quite distinct from either, beiug more symmet- 

 rical and less ugly. The tendency seen in li. ohtusifolius to exhibit red midribs and 

 speckles on the leaves is exaggerated in the hybrid. 



tRumex Acetosella, L. Field Sorrel. Horse Sorrel. 

 Last half of May. 



PODOSTEMACEiE. 



Eiver-weed Family. 



Podostemon ceratophyllus, Michx. River-weed. 



Rock Creek, below Lyon's Dam ; Difficult Run. June, July. 



ARISTOLOCHIACEiE. 



BiRTHwoRT Family. 



t Asarum Canadense, L. Wild Ginger. Asarabacca. 

 Last of April or first of May. 



t Aristolochia Serpentaria, L. Virginia Snakeroot. 

 Widely distributed, but nowhere abundant. June. 



PIPERACE-ffJ. 



f Saururus cernuus, L. Lizaed's Tail. 

 July. 



LAURA-CEiE. 



Laurel Family. 

 t Sassafras officinale, Nees. 



April. For an attempt to explain the significance of the rudimentary organs of 

 Sassafras, Lindera, and other Lauraceous plants, see my paper on " Homologies in 

 the Lauraceai," read before the A. A. A. S. at Saratoga, and published in the Scien- 

 tific American, Supplement, of Sef tember 20, 1879, p. 3083. 



t Lindera Benzoin, Meisner. Spice bush. Benjamin-bush, 

 March, April. 



THYMELEACEiE. 



Mezereum Family. 



Dirca palustris, L. Leather-wood. Moose-wood. 

 Second or third week in Aiiril. 



