CiSTALES.] 



BRASSICACE.E. 



3.51 



Order CXXIII. BRASSICACE^.— Crucifers. 



Cruciferac, Juss. Gen. 237. (1789) ; DC. Mdmoire sur les Crudferes ; Syst. 2. 139 ; Prodr. 1. 131 ; Bartl. 

 Ord. Nat. 261 ; Endl. Gen. clxxxi. ; Meisner, Gen. p. 9. 



Diagnosis. — Cistal Exof/ens, with tetramerous floicers and tetradynamous stamens. 



Herbaceous plants, annual, biennial, or perennial, very seldom suffruticose. Leaves 

 alternate. Flowers usually yellow or white, seldom purple, without bracts, generally 

 in racemes. Sepals 4, deciduous, imbri- 

 cate or valvate. Petals 4, cruciate, alter- 

 nate with the sepals. Stamens 6, of which 

 two are shorter, sohtary, and opposite the 

 lateral sepals ; occasionally toothed ; and 

 four longer, in pau's, opposite the anterior 

 and posterior sepals, generally distinct, 

 sometimes connate, or fui'nished with a 

 tooth on the inside. Disk with various 

 green glands between the petals and the 

 stamens and ovary. Ovary superior, 

 unilocular, with parietal placentae usually 

 meeting in the middle, and fonning a 

 spurious dissepiment. Stigmas 2, oppo- 

 site the placentae. Fruit a sUique or 

 sihcule, 1 -celled, or spm'iously 2-celled ; 

 1- or many-seeded ; deliiscing by two 

 valves separating from the replum ; or 

 indehiscent. Seeds attached in a single 

 row by a funiculus to each side of the 

 placentae, generally pendulous. Albumen 

 none. Embryo with the radicle folded 

 upon the cotyledons, which are occasion- 

 ally sHt or lobed. 



This Order is among the most natm^al 

 that are known, and its character of 

 having what Linnaean Botanists call tetra- 

 d;y'namous stamens is scarcely subject to 

 exception. It has a near relation to 

 Capparids, with which it agrees in the 

 number of the stamens of some species of 

 that Order, in the fniit having two pla- 

 centae and a similar mode of dehiscence, 

 and m the quaternary number of the 

 divisions of the flower. To Foppyworts 

 it is thought to approach in the unusual 

 number of the petals and m the stnictm'e 

 of the fruit of some genera of that Order, such as Glaucium and Chelidonium ; with the 

 siliquose-fniited Fumeworts it has also some analogy, and even with the whole of that 

 Order m the number of its petals, supposing the conmion opinion of the nature of the 

 floral envelopes of Fumeworts to be correct, or m the binary division of its flower, from 

 which the quaternary is only a slight deviation, upon the hypothesis I have suggested 

 in speaking of that Order. But the totally different structm-e of the seed forbids 

 Crucifers to be associated in the same group with the latter. 



Crucifers may be said to be characterised by their deviation from the ordinary 

 symmetry observable in the relative arrangement of the parts of fructification of other 

 plants, — deviations which are of a very interestmg nature. Their stamens are an'anged 

 thus : two stand opposite each of the anterior and posterior sepals, and one opposite 

 each of the lateral sepals ; there being 6 stamens to 4 sepals, instead of either 4 or 8, 

 as would be nonnal. Now in what way does tliis arise ? Is the whorl of stamens to be 

 considered double, one of the series belonguig to the sepals, and one to the petals, and, 

 of these, a part imperfect ? I am not aware of any such explanation havuig been 

 offered, nor do I know of a better one. It appears to me that the outer series is incom- 

 plete, by the constant abortion of the stamens usually belongmg to the anterior and 



Fig. CCXLII.— Erucastrum Canariense. 1. a flower ; 2. the stamens ; 3. the siliqua, with the valve 

 separating from the replum ; 4. a transverse section of a seed ; 5. a perfect seed. 



Fig. CCXLII. 



