210 



SYSTEMATIC BOTANY. 



placentas. Fruit: a silique (fig. 349) or a silide (fig. 350), 

 usually 2-celled by the replum, from which the valves separate 

 in dehiscence, leaving the placentas as a frame : or 1-celled from 

 the imperfection of the replum (fig. 350), and indehiscent or 

 breaking across at constricted places ; seeds generally pendulous 

 in a single row on each placental margin, the two rows either 

 intercalated in one line or in two collateral lines on the replum ; 

 embryo with the radicle variously folded on the cotyledons, 

 without perisperm. 



Pig. 350. 



Fig. 351. 



OJ 



Fig. 350. Silicle of Isatis : a, entire ; 6, cross section. 



Fig. 351. Burst silicle of Thlaspi. 



Fig. 352. Seed of Erysimum cut vertically : a, funiculus. 



De Candolle divided this large and very natural Order into 

 Suborders, founded on the mode of folding of the embryo, thus : 

 1. Pleurorhizce ( O =), with the radicle turned round the sides or 

 edges of the flat, accumbent cotyledons ; 2. Notorhizce (o||), with 

 the radicle folded against the back of one of the flat, incumbent 

 cotyledons; 3. Ortlwplocce (o > >), the radicle similarly folded, 

 but the incumbent cotyledons longitudinally folded (induplicate) so 

 as partly to surround it; 4. Spirolobece (o||||), the cotyledons 

 linear, incumbent, and folded or rolled over on themselves and 

 against the radicle; 5. Diplocolobece (o|| || ||), the cotyledons linear 

 incumbent, and twice or thrice transversely folded. 



Some writers have established Suborders on the characters of the 

 fruit, using those of the embryo for subdivision, thus : 1. Sili- 

 quosce, with a silique opening by valves ; 2. Siliculoscn latiseptce, 

 with a silicule opening by valves, the replum in the broader diame- 

 ter ; 3. Siliculosce angustiseptce, a valved silicule with the replum in 

 the narrower diameter ; 4. Nucumentacece, with an indehiscent 

 silicule, often 1-celled without a replum ; 5. Septulatce, with the 

 valves bearing transverse septa in the inside : 6. Lomentacece, with 

 a pod breaking across into 1-seeded pieces, sometimes with a 1-2-, 

 seeded beak above the abortive true pod. Bentham and Hooker's 

 arrangement closely corresponds with this : but the Suborders are 

 all more or less artificial. 



