CBUCIFEB^J. 211 



All Crucifers have certain common constant characters : the 

 quaternary perianth ; the cruciate sepals and petals, with the latter 

 free and imbricate ; the non-adherent gynseceum ;* its normally 

 binary structure, with the carpellary leaves united into a really one- 

 celled ovary with parietal placentation, 2 the cavity being at first 

 undivided ; :i finally, the indefinite inflorescence. 



Next to these absolute (?) characters come others, which are all 

 but constant, with single or very few exceptions, viz. : the convex 

 receptacle, with hypogynous insertion, except in one genus ; 4 the 

 definite androceum, hexandrous and tetradynamous (polyandry 

 occurs in one species ; s there are fewer than six stamens in certain 

 cases of reduction 6 ) ; the absence of albumen in the seeds ; the in- 

 flexion of the embryo ; the alternation of the leaves ; the absence of 

 stipules at their base ■/ the absence of bracts where the floral pedicels 

 spring from the axis of the inflorescence. 3 



The characters of frequent variation differ in occurring in most 

 of the organs both of vegetation and reproduction. We may enu- 

 merate them : — 



1. The root may be fibrous or fascicled, or a tap-root. In the 

 latter case it becomes the seat of the deposit of a quantity of nutri- 

 tive matter ; and is then edible, as in the Turnip, Radish, &c. 



2. The stems varv in duration ; they are usualty herbaceous, 

 whether annual or perennial. 9 They are rarely frutescent ; still more 

 rarely climbing, as in Cremolobus. Sometimes they have a creeping 

 rhizome, covered with scales representing rudimentary leaves. 10 



3. The leaves are generally alternate ; but in Dentaria they are 



a very ill-known Chilian plant; — 2. Discov'uun s Megacarpea poll/ xndra DC. 



(Rafin., ex DC, Prodr., i. 120) ;— 3. Mali- « See p. 215, n. 12. 



molobos (Tattsch, in Flora, 1836, 410), whereof ' That is, of well-developed stipules when 



the same may be said ; — 4. Microstigma they are adult. (See p 212, n. 4.) 



Tkautv., ex Likdl., Teg. Kingd., 335b), whose 8 For the exceptions see p. 212, n. 7. 



name alone is published. 9 Spineseer.t in certain species. 



1 Even in Subularia, where the receptacle is 10 The anatomical structure of the stem has 

 concave, the ovary is not at all adherent to it. beenchiefly studied by UAUTiG(m Bot. Zeit., 1859, 



2 The placentations that have been described 109), in Arabis, and by Hanstein (in Pringsh. 

 as basilar or apical, are so only in appearance Jarhb., i. 231), who has traced the connexion of 

 when adult. At first they are really parietal the arrangement of the leaves with that of the 

 placentas, reduced to the short portion near their fibro-vascular bundles in the stem (Oliv., Stems 

 base or apex. (See p. 215, n. 13.) in Dicot., 6 ; in Nat. Mist. Rev., ii, 303). The 



3 The production of the false septum is always aerial axes of certain species of Dentaria (D. 

 late. bulbifera L., &c), bear axillary bulbils. 



i 



Subularia. 



2 



