VI. OCRUCIFERA. 23 
very short or reduced to a corymb when the flowering com : 
mences,. but lengthen out as it advances. Sepals 4. Petals 4, 
equal, or two (on the outer side) larger. Stamens 6, of which 
two are generally shorter or very rarely deficient. Ovary 
solitary, 2-celled. Style single, often very short or almost 
none, with a capitate or 2-lobed stigma. Fruit a pod, divided 
into 2 cells by a thin partition, from which the valves gene- 
rally separate at maturity ; or, in a few genera, the pod is one- 
celled or indehiscent, or separates transversely into several 
joints. Seeds without albumen, attached, in each cell, alter- 
nately, to the right and left edges of the partition. 
An extensive and very natural family, widely spread over the globe, but 
chiefly in the northern hemisphere; scarce within the tropics, and in some 
districts entirely unknown. The number of sepals, petals, and stamens 
readily distinguish Crucifers from all other British plants, but the discri- 
mination of the numerous genera into which they are distributed is a much 
more difficult task. The characters are necessarily derived chiefly from the 
pod and the seed, and are often very minute. It is therefore absolutely 
necessary, in order to name a Crucifer, to have the specimen in fruit, and, 
to examine the seed, it must be ripe; it should then be soaked, and the 
outer coating carefully taken off, in order to lay bare the embryo, and 
observe the position of the radicle on the cotyledons, which is now considered 
as the most essential among the generic characters. 
A few terms specially made use of in describing plants of this family 
may require some explanation. The calyx is said to be d¢saccate when two 
of the sepals, a little outside the two others, are broader at the base, form- 
ing little protuberances or pouches. The pod is termed a szlique or siliquose 
when linear, at least three or four times as long as broad; a silicule or sili- 
eulose when short and broad—not twice as long as broad; and a lomentum 
or lomentose when it does not open its valves. The nerves on the pod, 
often used as a generic character, can be best seeh on dried specimens; 
_ they are even sometimes quite imperceptible on the fresh pod. The seeds 
are said to be 7m one row when, from the narrowness of the pod or the 
length of the seed-stalk, they occupy the centre of the cell, the two rows 
being as it were blended into one; or in two rows, when the two rows are 
distinct without overlapping each other. Inthe embryo, the radicle is said 
to be accumbent when it is bent down on the edges of the cotyledons, 
incumbent when bent over the back of one of them; in the latter case the 
cotyledons are either flat or conduplicate, that is, folded longitudinally over 
the radicle. 
It must be admitted, however, that, notwithstanding all these nice dis- 
tinctions, the genera of Crucifers as at present defined, are often as artificial 
as they are difficult. But as the remodelling them is not a work to be 
undertaken in a local Flora, I have selected, from those adopted in the best 
modern Floras, such as have appeared to me the most natural. The follow- 
ing Table is founded, as much as possible, on less minute characters, but, 
even in the few British species, itis feared that the examination of the seed 
cannot always be wholly dispensed with. 
