[ 1 6 3 1 ]
SISYMBRIUM Irio,
London Rocket.
l/b
TETRADYNAMIA Siliquosa.
Gen. Char. Pod cylindrical, bursting with nearly
straight valves. Cal. and Cor. spreading.
Spec. Char. Leaves runcinate, toothed, naked. Stem
smooth. Pods erect.
Syn. Sisymbrium Irio. Linn. Sp. PL 921. Sm. FI,
Brit. 705. Huds. 297. With. 583. Hull. 150.
Relh. 258. Sihth. 207. Curt. Lond. fasc. 5,
t. 4 8 . Jacq. Austr. t. 322,
Erysimum latifolium neapolitanum. Raii Syn. 298,
T h i s species of Sisymbrium is chiefly known in waste
ground about London near the Thames, In Chelsea garden,
and all that neighbourhood, it is a troublesome weed. I he
root is annual, the flowers are produced from May to August,
and the seeds ripened during most of that period in great profusion.
After the fire of London it is said to have been peculiarly
abundant; whence some botanists of that time, not
being able to trace its origin, deduced an argument in favour
of spontaneous generation: an argument as unnecessary to be
refuted now, as some opinions concerning sky-fallen stones
may be a century hence.
The herbage of this plant is generally quite smooth, yet not
so completely as Mr. Curtis mentions, for the upper part of
the stem is often downy, and the calyx hairy. Stem about
2 feet hiffh, branched, round. Leaves alternate, pinnatifid;
the lobes recurved, toothed chiefly at the upper edges. Flowers
small, yellow. Pods numerous, long, slender, rugged when
ripe. ’ Taste of every part like mustard.
I beg leave here to mention that my worthy friend Dr. Cray
of the British Museum has very properly reminded me of his
having many years ago shown me specimens of b.murale,
which, at p. 1090 of this work, is mentioned as a more recent
discovery. We then judged it a variety of S. tenuifolmm, and
it escaped my recollection. Other botanists, indeed, have shown
me real varieties of tentcifolium for murule,