Bulletin - United States National Museum - Smithsonian Institution

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 westward
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 Alexandria.
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. Professor
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.