536 PART IV. CLASSIFICATION. 



as a spurious dissepiment (Figs. 348 D* E* v, 288 C w}. When 

 the fruit opens, the pericarp splits into two valves corresponding 

 to the carpels, leaving their margins, as a frame or replum, bearing 

 the placentse with the spurious dissepiment attached : the seeds 

 remain attached to them for some time (Fig. 288 C, p. 474). 



The flowers are in racemes in which the bracts are suppressed ; 

 when the lower pedicels are longer than the upper ones, the raceme 

 becomes a corymb, and then the lower flowers are usually zygomor- 

 phic, the petals turned towards the periphery being larger than 

 those directed towards the axis of the inflorescence, as in Iberis. 



The form of the fruit is of importance in the subdivision of this 

 order. In some genera it is much longer than it is broad, when it 

 is termed a siliqua, (Figs. 288 (7, 348 (7) ; in others, it is not much 

 longer, or about as long as it is broad, when it istermed a silicula 

 (Fig. 348 D and E}. The latter is commonly somewhat com- 

 pressed in one direction ; either parallel to the dissepiment, that is 

 to say laterally (Fig. 348 E and E*), so that the dissepiment lies 

 in the direction of the greatest diameter, when it is latiseptal ; or 

 perpendicularly to the dissepiment, that is in the median plane, 

 so that the dissepiment lies in the narrowest diameter, when it is 

 angiistiseptal (D and /)*). Fruits with only one or a few seeds, and 

 which are indehiscent, are confined to only a few genera, such as 

 Isatis (Fig. 348 F). So likewise is the jointed siliqua, which has 

 transverse dissepiments between the seeds ; when they are ripe it 

 divides transversely into segments, as in Raphanus (Fig. 348 Gr). 



The seed is exalbuminous. The embryo is folded in the seed 

 in various ways ; the radicle may lie in the same plane as one of 

 flat cotyledons (Fig. 348 K), when the cotyledons are said to be 

 incumbent, Notorhizecc (the diagram being Q ||) ; or the radicle 

 may occupy the same position, the cotyledons being folded (Fig. 

 348 7), when the cotyledons are said to be incumbent and folded, 

 Orthoploceoe. (diagram of section Q ^>) ; or, thirdly, the radicle may 

 be lateral to the two cotyledons (Fig. 348 //), when the cotyledons 

 are said to be accumbent r Pleurorliizece (diagram Q =) : more 

 rarely the cotyledons are spirally rolled so that in a transverse 

 section they are cut through twice, Spirolobece (diagram Q || ||) ; 

 or, finally, they may be doubly folded, and be seen four times in 

 a section, Diplocolobem (diagram Q II II II ID- The seeds contain 

 much fatty oil. 



Sub-order 1. SILIQUOS.E. Fruit a siliqua, much longer than it is 

 broad. 



