4.02 STATISTICS OF THE ORDER CRUCIFERZ. 
live only one year, and some for three years. But on this subject 
we will write more in detail on some future occasion. In this 
Order the plants that die after producing flowers and seed—the 
true idea of an annual or biennial—are about three times as many 
as those that live for some time at least after producing seeds, or 
in other words, those that flower and bear seeds oftener than once 
are but about one-third of the number that only perform this 
function of life for once and then perish. This fact materially 
affects the distribution of the species, as we shall see hereafter. 
All the Brassicas and Mustards, the Barbareas, Turritis, Arabis 
hirsuta, A. ciliata, and A. Turrita are annual or biennial. Of 
the Cardamines three are annual, viz. C. impatiens, C. hirsuta, 
and C. sylvatica. All the Sisymbriwms are annual; so are the 
Scurvy-grasses. Several of the Thlaspi, Hutchinsia, Teesdalia,. 
Lepidium campestre, L. ruderale, and L. sativum, Senebiera, Isatis, 
and Raphanus are of the same duration. Hesperis is reputed 
annual or biennial, but it has been known to grow up more than 
once from the same root (it usually lives and flowers two sea- 
sons). We suspect the Wallflower is not a longer-lived plant 
than the Hesperis is. The Stocks only flower once from the same 
root in our gardens. Do they really enjoy a longer existence in 
their native fastnesses ? 
Few plants in this Order have creepimg roots. Here the 
normal form of the root is tapering and vertical in its direction. 
Hence though some of them are exceedingly long-rooted, as the 
Hedge Mustard (Sisymbrium officinale), and even the Shepherd’s 
Purse, the Tower Mustard, and many others, yet their duration 
is only annual. Two of the Cardamines (C. pratensis and C. 
amara) have bulbous, toothed, and somewhat ereeping roots. Se- 
veral Nasturtia have creeping roots (N. sylvestre and N. amphi- 
bium). N. palustre, N. terrestre, Sm., has a tapering root, and 
» is by some botanists considered to be perennial; but probably 
_ this wants confirmation. The tapering-rooted plants of this 
Order, whether the root be ligneous, as in the Stock, or fleshy, 
as in the Turnip, etc., indicate a duration of not more than two 
years, or in other words, they live till they have produced seeds 
and no longer. To this rule Armoracia rusticana supplies a re- 
markable exception; but exceptio probat regulam, “there is no 
rule without an exception.”’? The root of Horse-radish is vertical, 
but-it is so full of vitality that a small bit of it, under any cir- 
