ADDISONIA 3 
(Plate 162) 
DIPLOTAXIS TENUIFOLIA 
Wall-rocket 
Native of Europe 
Family BRASSICACEAE MustTarp Family 
Sisymbrium tenuifolium 1,. Cent. Pl. 1: ome $753; 
Diplotaxis tenuifolia DC. Syst. 2: 63. 182 
In 1916, plants of a = eee character were grown at the 
New York Botanical Garden from seed received from the Zurich 
botanical garden, and they proved to be Diplotaxis tenuifolia. The 
pale green foliage and light yellow flowers made a rather pleasing 
combination of color, and the fragrance of the blooms was not 
unpleasant. The branching and floriferous habit suggested pos- 
sible value as a flower garden subject, and the following year plants 
were raised from collected seed and placed in the flower borders 
near Conservatory Range 1. From these plants our illustration 
was taken. 
The wall-rocket has inclined to spread over more than its allotted 
share of ground, and to become weedy in habit, but it has a long 
blooming season, and a plentiful supply of small flowers, giving, 
with the gray-green leaves, the same general color effect as the 
yellow alyssum, Alyssum saxatile compactum. It must be kept 
within bounds, especially by discarding seedlings which spring up 
within several yards of the old plants. The plant may readily be 
propagated by seeds. 
The wall-rocket, so called because it is found so often on old 
walls in England, with other related species, is the Sisymbrium 
tenuifolinm of older botanies, described by Linnaeus in 1755, but 
later separated into the genus Diplotaxis, of which tenuzfolia is the 
type species. It differs from Sisymbrium in having a flattened 
pod, and in the arrangement of the cotyledons in the seed; and 
from Brassica in having the seeds in two rows in each half of the 
pod. In this country it is adventive from Europe, occurring near 
the sea-coast in the northeastern States and California. 
The wall-rocket is an annual or biennial herb, one to two feet 
high, bushy and branching, with smooth somewhat glaucous 
stems. The leaves are slightly glaucous, gray-green in color, 
pinnatifid, the lobes sinuately toothed, the lower ones three to four 
inches long, alternate, and sessile, the upper smaller and more 
