j6 THALAMIFLORiE 



Natural Order VI 

 CRUCIFERZE.— The Cruciferous Tribe 



A very large and important Order, well described by the name cruci- 

 ferous, or cruciform, there being invariably 4 petals, which are placed 

 cross-wise ; stamens 6, of which two opposite ones are 

 shorter than the rest ; seed-vessel either a long pod, 

 ^ a silique, composed of two valves and a central par- 

 ^ tition, or a shorter pod called silicle, or pouch, which 

 is for the most part, but not alwaj's, similarly con- 

 structed. At the base of the stamens are generally 

 two green glands, which secrete honey. Most of the 

 plants of this Order possess, in their wild state, 

 stimulant properties, and ari acrid flavour, though 

 none of them are poisonous ; in medicine they afford 

 a valuable remedy for scurvy. Under cultivation 

 many of them assume a succulent habit of growth, 

 and hold the first rank among esculent vegetables. The various 

 kinds of cabbage, kale, broccoli, turnip, radish, and cress are the 

 most remarkable examples. They contain a great deal of nitrogen 

 gas, to the presence of which is to be attributed their unpleasant 

 odour when rotting. Some contain a large portion of sulphur. 

 Oil is contained in the seeds of many, in such quantities as to be 

 a valuable article of commerce. There are some twelve hundred 

 species, distributed chiefly over the northern hemisphere, par- 

 ticularly in the cold and temperate regions. Upward of two hundred 

 grow in the frigid zone, where they form a large proportion of the 

 vegetation. In the tropics they are uncommon, and in certain 

 districts the Order is quite unrepresented. This Order contains all 

 the plants which were placed by Linnseus in the class Tetradynamia, 

 that is, all such as are distinguished by having 6 stamens, 4 long and 

 2 short. Modern botanists found the main distinctions of the 

 genera on the position of the radicle or embryo root, with relation 

 to the cotyledons, or seed-lobes ; but as this arrangement presents 

 difficulties to the young student in botany, it is not considered 

 advisable to adopt it here. 



Seed-vessel, a pouch (silicle) or short pod. Pouch 2-valved, 

 ivith a central vertical partition. 



1. Thlaspi (Penny Cress).— Po/rA rounded, flat, notched ; 

 valves boat-shaped, winged at the back ; seeds nmnerous. (Name 

 from the Greek, thlao, to flatten.) 



2. Capsella (Shepherd's Purse).— P»//(7;. inversely heart-shaped, 

 flat ; valves boat-shaped, keeled, but not wmged ; seeds numerous- 

 (Name, a little capsa, or seed case.) 



