518 



BOTANY 



Fig. 476. — Crueiferae. Floral 

 diagram ( 



a multiplication of its carpels has taken place only in a few cases 

 (Papaver). 



Family Crueiferae. — Flowers actinomorphic ; calyx of two 

 TWO-MEROtrs WHORLS ; corolla tetramerous ; andrcecium consisting of 



AN OUTER WHORL OF TWO SHORT STAMENS 

 AND AN INNER OF FOUR LONG STAMENS DIS- 

 POSED IN PAIRS ; gyncecium always dimer- 

 ous ; ovary divided by false dissepiments 

 INTO TWO LOCULI. Fruit rarely indehiscent, 

 usually a capsule ; seeds without endo- 

 sperm; embryo curved (Figs. 476-479). 



The Crueiferae are glabrous or hispid herbs 

 (rarely small shrubs) with entire, toothed or 

 lobed leaves. The white or yellow flowers, 

 rarely red or violet, are generally small and 

 aggregated into racemes, usually without bracts and bracteoles. The 

 flowers of the inflorescences develop so gradually in acropetal succes- 

 sion, that frequently the ripe fruit is already produced at the base of 

 the raceme while the apex of the axis with its undeveloped buds is 

 still in process of elongation (e.g. Gapsella bursa pastoris). Although 

 the colour of the petals, and also the nectaries at the base of the 

 stamens, undoubtedly represent an attractive apparatus for insects, self- 

 pollination is of frequent 

 occurrence in this order. 

 The capsules are either 

 much longer than broad, 

 and are then distinguished 

 as SILIQU^E, or they have 

 the form of short and 

 broad siliculs; (Fig. 478). 

 Indehiscent fruits (Fig. 479) 

 occur less frequently. 

 They are often lomentace- 

 ous in character and sep- 

 tated transversely by false 

 partition - walls, breaking 

 when ripe into a corre- 

 sponding number of seg- 

 ments. A fruit of this 

 nature is termed a jointed 

 siliqua. The two forms 

 of fruit, dehiscent and in- 

 dehiscent, do not differ essentially in structure : both are sometimes 

 borne by the same plant. Many Crueiferae contain a pungent, nitro- 

 genous or sulphurous ethereal oil, which exists in an uncombined state 

 in the vegetative organs (e.g. Horse-Kadish), but in the seeds (e.g. 



Fig. 477. — Baphaniis sativus. a, Flower (nat size) ; b, petal ; 

 c, andrcecium and gyncecium ( x 2) ; d, pistil with disc- 

 glands (x 2) ; e, fruit (nat. size) ; /, transverse section of 

 fruit ; g and h, embryo. (Magnified.) 



