452 SYSTEMATIC BOTANY. 



often 1 -celled, owing to the absence of the replum. Ex- 

 ample : — Isatis. 



Sub-order 5. SeptulatcE. — The valves of the fruit opening 

 longitudinally, and bearing transverse septa in their interior. 

 No examples among British plants. 



Sub-order 6. Lomentacece. — Fruit a siliqua or silicula, dividing 

 transversely into 1-seeded portions, the true siliqua sometimes 

 barren ; the beak placed above it containing one or two seeds. 

 Examples : — Cakile, Raphanus. 



These sub-orders are further sub-divided into Tribes, accord- 

 ing to the mode of folding of the embryo. 

 The sub-orders founded on the mode in which the embryo 



is folded, which was first adopted by De Candolle, and which 



is more generally used, is as follows: — 



Sub-order 1. Pleurorhizece (O =) (fg- 756). — Cotyledons 

 accumbent, flat ; radicle lateral. Examples: — Cheiranthus, 

 Nasturtium, Arabis. 



Sub-order 2. Notorhizeoe (O II) (fig- 755). — Cotyledons incum- 

 bent, flat; radicle dorsal. Examples ;— Hesperis, Sisymbrium, 

 Isatis. 



Sub-order 3. Orthophcea (O ^) (fig 867).— Cotyledons con- 

 duplicate, longitudinally folded in the middle ; radicle dorsal, 

 within the fold. Examples : — Brassica, Sinapis, Kaphanus. 



Sub-order 4. SpirolobecB (O II II) (fig^- 754 and 866). — Coty- 

 ledons twice folded, linear, incumbent. Examples : — Bunias, 

 Erucaria. 



Sub-order 5. Diplecolohece (Q 1| || ||). — Cotyledons thrice 

 folded, linear, incumbent. Examples : — Senebiera, Subularia. 



Distribution and Numbers. — The plants of this order chiefly 

 inhabit temperate climates. A large number are also found in 

 the frigid zone, and a few in tropical regions chiefly on moun- 

 tains. Lindley enumerates 195 genera, including about 1600 

 species. 



Properties and Uses. — This order is generally characterised 

 by antiscorbutic and pungent properties, frequently combined 

 with acridity. Tlie order is one of tlie most natural in the 

 Vegetable Kingdom, and does not contain a single poisonous 

 plant. The seeds fi-cquently contain a fixed oil. Many of our 

 commonest culinary vegetables are derived from it. The Cruci- 

 fera; are also interesting in a clicmical point of view, as many 

 of thorn contain much nitrogen and sul|)hur, and, according 

 to Mulder, the common Water-cress {Nasturtium officinale) 

 contains iodine. The more interesting plants are the follow- 

 ing:— 



Nasturtium officinale— Tins plant is the common Water-cress, so well known 

 as an excellent and wholesome salad. 



Cardamine pratensis, Cuckoo-flower. — The flowers were formerly much 



