450 SYSTEMATIC BOTANY. 



but these are unimportant, and require no special notice. Some 

 species are cultivated in our gardens and greenhouses. The 

 most important of these is Dicentra {Dielytrd) spectabilis, which 

 has very showy flowers, but, like all other plants of the order, it 

 is scentless. 



Natural Order 1 5. Crucifer^ or BRASSiCACEiE. — The 

 Cruciferous or Cabbage Order (figs. 860 — 867). — General 

 Character. — Herbs, or very rarely shrubby plants. Leaves 

 alternate, exstipulate. Floioers usually yellow or white, rarely 

 purple, or some mixture of these colours ; inflorescence racemose 

 \fig. 861), or corymbose; usually ebracteated. Sepals 4 (fiy, 

 860), deciduous; cestivation imbricate or rarely valvate. Petals 

 4 (fiys. 421 p, and 860), hypogynous, arranged in the form of a 

 Maltese cross, alternate with the sepals, deciduous. Stamens 6, 

 tetradynamous (fig. 862, ec), hypogynous. Thalamus furnished 

 Avith small green glands (figs. 422 and 862 gl), placed between 

 the stamens. Ovary superior (fig. 862), with two parietal pla- 

 centas (fig. 860), 1-celled, or more usually 2-celled (fig. 860), 

 from the formation of a spurious dissepiment called the replum 

 {figs. 600 c/, and 863) ; style none (fig. 862) ; stigmas 2 (fig 

 864), opposite the placentas. Fruit a siliqua (figs. 666 and 

 863), or silicula (figs. 864 and 865), 1 or 2-celled, 1 or many- 

 seeded. Seeds stalked, generally pendulous (fig. 863); embryo 

 with the radicle variously folded upon the cotyledons (figs, 755, 

 756, 866, and 867); albumen none. 



Diagnosis. — Herbs. Bracts generally absent. Sepals and 

 petals 4, deciduous, regular, the latter cruciate. Stigmas 2, 

 opposite to the placentas. Stamens tetradynamous. Fruit a 

 siliqua or silicula. Seed without albumen, and with the radicle 

 variously folded upon the cotyledons. No other order is likely 

 to be confounded with this if ordinary care be taken, as tetradyna~ 

 mous stamens only occur here, except in a very few plants belong- 

 ing to the natural order Capparidacece. (See Capparidace^.) 



Division of the Order, and Examples of the Genera. — This 

 large and truly natural order has been divided into sub-orders 

 according to the nature of the fruit, and also as to the mode in 

 which the embryo is folded. The sub-orders founded on the 

 nature of the fruit are as follows : — 

 Sub-order 1. Siliquosce. Fruit a siliqua (fig. 863), opening by 



valves longitudinally (fig. 666). Examples: — Cheiranthus, 



Brass ica. 

 Sub-order 2. Siliculosa: latiseptce. Fruit a silicula opening by 



valves; the replum in its broader diameter (fig. 865). Ex- 



amples : — Cochlearia, Armoracia. 

 Bub-ordcr 3. Siliculosce angustiseptce. Fruit a silicula opening 



by valves; the replum in its narrower diameter (fig. 864), 



Examples : — Thlaspi, Iberis. 

 6iib-order 4. Nucumentacea. Fruit an indchiscent silicula, 



