66 FLORA OF WASHINGTON AND VICINITY. 



tDraba verna, L. Whitlow-Grass. 

 February to April. 



Hesperis matronalis, L. Rocket. 

 Middle to end of May. 



t Sisymbrium officinale, Scop. Hedge-Mustard, 

 May to June. 



t Sisymbrium. Thaliana, Gay. Mouse-ear Cress. 

 Middle of March to end of April. 



Sisymbrium ^Hirtria, Scop. [Alliaria officinalis, Andrz. Erysimum Alliaria, L.] 



April. Abundant in the Georgetown College Grounds, and now extending west- 

 ward as far as Foundry Run. 



tErysimum. cheiranthoides, L. Worm-seed Mustard. 

 Rather rare. Third week iu June. 



t Camelina sa^iua, Crantz. False Flax. 



'Rather rare and apparently disappearing. Found in the city, in the vicinity of 

 Twentieth street and Virginia Avenue ; also above Georgetown and below Alexan- 

 dria. Second week in May. 



Brassica Sinapistrum, Boiss. Charlock. 

 Seldom seen. June to August. 



Brassica nifjra, Koch. Black Mustard. 



Virginia shore of the Potomac, below Chain Bridge. July. 



t Capsella Biirsa-pastoris, Moench. Shepherd's Purse. 

 March to June. 



tLepidium Virginicum, L. Wild Peppergrass. 



May. 



iliepidiura campestre, L. 



Often found far out in the woods, as if indigenous. May. 



Thlaspi arvense, L. Field Pennycress. Mithridate-Mustard. 



Formerly found near Jackson City, Va. (Dr. Vasey). Now exterminated. Pro- 

 fessor Chickering finds this plant on Sugar Loaf Mountain, Maryland. 



Raphanus sativus, L. Radish. 



Georgetown College Grounds, escaped. May. 



CISTACE^. 



Rock-Rose Family. 



t Helianthemum Canadense, IVIichx. Frost- weed. 



Found sparingly in Maryland. Second or third week in May. 



Lechea minor, Walt. Pin-weed. 



End of May. Radical leaves usually gone at flowering time. They may be col- 

 lected from December to April. 



