THE CHARLOCK— continued. 
flowers, long pods with partitions across their wider diameters, either not compressed 
or compressed parallel to the septum, with their seeds in one or two rows, and with 
the cotyledons folded conduplicately or lengthwise so as to clasp the incumbent radicle. 
The genus Diplotaxis is distinguished by its compressed pods and two-ranked seeds ; 
whilst Brassica and Sinapis are, as we have said, distinguished only by the direction of 
their sepals. 
It is not surprising that several allied yellow-flowered Crucifers are often 
confused under the name of Charlock, including its more useful congeners the Black 
and White Mustards {Sinapis nigra Linn6 and S. alba Linn6). The seedlings 
of Charlock can be distinguished from those of the Turnip {Brassica Rapa Linne) by 
the first foliage-leaves, the cotyledonary leaves being nearly identical. The Turnip 
has a long-stalked round leaf ; the Charlock an almost stalkless obovate one of a 
darker green. From the other Mustards the best distinctions are the pods. Charlock 
has a slightly angular, straight-sided pod ending in a conical beak which sometimes 
contains one seed ; whilst White Mustard has a shorter pod constricted into several 
bead-like portions and ending in a curved sword-like beak which is longer than the 
rest of the pod and is also sometimes one-seeded ; and Black Mustard has a four- 
sided pod, closely pressed against the stem and ending in a short subulate seedless 
beak. 
The dark brown seeds of the Charlock are unfortunately hardly distinguishable 
from those of the Turnip and retain their power of germination for several years if 
deeply buried, thus coming up at irregular times. Though an annual, the plant is 
thus a serious pest on light soils, especially calcareous loams. The most effective 
remedy against It is spraying with copper-sulphate. Charlock has a rough stem, 
one to two feet high, and branched ; stalked lyrately-lobed lower leaves and sessile, 
lanceolate, irregularly serrate upper ones. Though not as large as those of the 
Cabbage, its flowers are larger than those of the allied Mustards, being often three- 
quarters of an inch across. The pods spread outwards from the stem and are 
from one to two inches long. 
The seeds contain some fixed or fatty oil, so that they occur as an impurity or 
adulterant in Rape or Colza oil-cake ; but their ground flour does not form on being 
moistened the pungent volatile oil of mustard, which in Black and White Mustard is 
the result of a complex fermentation set up by the action of a ferment or enzyme 
known as myrosin upon certain glucosides. Household mustard is prepared from 
an admixture of Black and White Mustard seed, to which Wheat-flour and Turmeric 
are often added ; but the Mustard of the Pharmacopoeia is 5. nigra Linne. 
