440 SYSTEMATIC BOTANY. 



{Dielytra) spectabilis, which has very showy flowers, but, like 

 all other plants of the order, it is scentless. 



Natural Order 15. Chucifer^ or Erassicaceje. — The 

 Cruciferous or Cabbage Order {Jigs. 863 — 870). — Character. 

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

 exstipulate. Flowers usually yellow or white, rarely purple, 

 or some mixture of these colours ; inflorescence racemose {fig. 

 864), or corymbose ; usually ebracteated. Sepals 4 {fig. 863), 

 deciduous ; (Estivation imbricate or rarely valyate. Petals 4 

 {figs. 419, p, and 863), hypogynous, arranged in the form of a 

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

 tetradynamous {fig. 865, ec), hypogynous. Thalamics furnished 

 with small green glands {figs. 420 and 865, gl), placed between 

 the stamens. Ovary superior {fig. 865), with two parietal pla- 

 centas {fig. 863), 1 -celled, or more usually 2-celled {fig. 863), 

 from the formation of a spurious dissepiment called the replum 

 {fig. 601, cl); style none {fig. 865); stigmas 2 {fig. 866), oppo- 

 site the placentas. Fruit a siliqua {figs. 668 and 867), or 

 silicula {figs. 867 and 868), 1 or 2-celled, 1 or many-seeded. 

 Seeds stalked, generally pendulous {fig. 867) ; embryo with the 

 radicle variously folded upon the cotyledons {figs. 757, 758, 

 759, 869, and 870) ; albumen none. 



Diagnosis. — Generally ebracteated herbs. Sepals and petals 

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

 the placentas. Stamens tetradynamous. Fruit a siliqua or 

 silicula. Seed without albumen, and with the radicle variously 

 folded upon the cotyledons. iVb other order is likely to be con- 

 founded with this if ordinary care be taken, as tetradynamous 

 staviuns only occur here, except in a very ftw plants belonging to 

 the natural order CappaHdacecB. 



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. Siliquoscs. Fruit a siliqua {fig. 866), opening by 

 valves longitudinally {fig. 668). Examples: — Cheiranthus, 

 Brassica. 



Sub-order 2. Silicidoscs latisept(S. Fruit a silicula opening by 

 valves ; the replum in its broader diameter {fig. 868). Ex- 

 amples : — Coehlearia, Armoracia. 



Sub-order 3. Siliciilos(B angustiseptcB. Fruit a silicula opening 

 by valves; the replum in its narrower diameter {fig. 867). 

 Examples : — Thlaspi, Iberis. 



Sub-order 4. Nucumentacea. Fruit an indehiscent silicula, 

 often 1-eelled, owing to the absence of the replum. Example: 

 — Isatis. 



