VI, CRUCIFER, 23 
mences, but lengthen out as it advances, Sepals 4. Petals 4, 
equal, or 2 (on the outer side) larger. Stamens 6, of which 
2 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 generally separate 
at maturity; or, in a few genera, the pod is l-celled or in- 
dehiscent, or separates transversely into several joints. Seeds 
without albumen, attached, in each cell, alternately, 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 discrimination of the numerous genera into which they are distri- 
buted is a very difficult task. The characters are 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 its fruit ; 
and to examine the seed, it must be ripe; it should then be soaked, 
and the outer coating removed, in order to lay bare the embryo, and 
observe the position of the radicle on the cotyledons, which affords 
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 bisaccate when 
two of the sepals, a little outside the two others, are broader at the 
base, forming little protuberances or pouches. The pod is termed a 
silique or siliquose when linear, at least three or four times as long as 
broad ; a stlicule or siliculose when short and broad—not twice as long 
as broad ; and a lomentum or lomentose when it does not open its valves. 
Lhe nerves on the pod, often used as a generic character, can be best 
seen on dried specimens; they are sometimes quite imperceptible on 
the fresh pod. The seeds are said to be im 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. In 
the embryo the radicle is said to be accwmbent 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. 
Notwithstanding all these nice distinctions, the genera of Cructfers 
as at present defined are often as artificial as they are difficult, under 
which circumstances I have selected those adopted in the best modern 
Floras, or such as have appeared to me the most natural. The following 
table is founded, as much as possible, on less minute characters, but 
even in the few British species the examination of the seed cannot 
always be dispensed with. - 
xi Pod with a longitudinal partition, generally opening in 2 valves. 2 
Pod not dehiscent, with 1 seed, or with several seeds eee by tr ans- 
| verse partitions (LOMEN'TOS ®) ‘ : PA 
