SECT. II 



PHANEROGAMIA 



519 



Fig. 478. — Fruit of a Siliculosa 

 angustisepta (Thlaspi ar- 

 (After Wossidlo.) 



Mustard seeds) it is combined, occurring in combination with other 

 substances, from which it is freed in the presence of water. 



The division of the Cruciferae into sub-families presents great difficulties. 

 The old classification proposed by Linn^us is now 

 regarded as too artificial. According to the nature of the 

 fruit, Linnseus first distinguished the two groups Sili- 

 quosae and Siliculosae : these he further divided into 

 Siliquosae nucamentaceae, with jointed siliquse, and 

 Siliculosae nucamentaceae, with indehiscent fruits. The 

 Siliculosae dehiscentes were afterwards divided by A. P. 

 de Candolle into S. latiseptae, with broad, and S. 

 angustiseptae, with narrow dissepiments. 



Another classification frequently employed at the 

 present time is that of de Candolle based on the 

 position assumed by the embryo within the seeds — (1) 

 Notorhizeae : cotyledons flat, with the radicle lying on 

 the surface of one of them ; diagram, Oil- (2) Orthop- 

 loceae : cotyledons folded, the radicle lying in the groove 

 of one of them ; diagram, O »■ (?) Pleurorhizeae : 

 radicle lateral to the two cotyledons ; diagram, Q =. 

 (4) Spirolobeae : cotyledons spirally rolled ; diagram, 



O II II- (5) Diplecolobeae : cotyledons doubly folded ; diagram, O II II II II- Prantl 

 has lately adopted a more natural classification, in which different organs (stigma, 

 nectaries, dissepiments, hairs) are taken into consideration. The old classifica- 

 tion of Linnjeus and de Candolle has been used on account of its greater 

 convenience. 



Representative Genera. — (1) Siliquosae dehiscentes: Oardamine (Bitter 

 Cress), with elastic valves ; Arabis (Rock Cress) ; Barbarea (Winter Cress) ; Nas- 

 turtium, in some cases with short siliquse ; Gheiranthus (Wall-flower) ; Matthiola 

 (Stock) ; Sisymbrium (Hedge-Mustard) ; Erysimum (Treacle-Mustard) ; Brassica ; 

 Sinapis (Mustard). (2) Siliquosae lomentaceae : Crambe (Kale), Oakile (Sea Rocket), 

 both strand plants ; Raphanus, the siliqua of the Garden Radish, R. sativus, is 

 spongy, not dividing into segments when ripe (Fig. 477). 



(3) Siliculosae dehiscentes latiseptae : Oochlearia ; Draba 

 (Whitlow Grass), siliculse lanceolate, somewhat com- 

 pressed ; A lyssum ; Lunaria (Honesty), siliculse very 

 broad and flat, with long stalks ; Camelina (False Flax). 



(4) Siliculosae dehiscentes angustiseptae : Thlaspi (Penny 

 Cress), silicula; flat, circular or cordate ; Iberis (Candy- 

 tuft), the racemes are corymbose, with marginal flowers 

 slightly zygomorphic ; Capsella (Shepherd's Purse), 

 siliculee triangular; Lepidium (Pepperwort). (5) Silicu- 

 losae nucamentaceae : Isatis (Woad). 



Geographical Distribution. — The Cruciferae are 

 chiefly found in the North Temperate Zone, growing in 

 the most varied situations. Cultivated species of 

 this order are : Brassica oleracea, the Cabbage, in numer- 

 ous varieties ; the primitive form grows wild along the coast of Western Europe ; 

 Brassica Napus var. oleifera, Rape ; var. Napobrassica, Turnip Cabbage ; Brassica 

 Bapa, Turnip ; var. oleifera, Colza ; B. nigra, Black Mustard ; Sinapis alba, 

 White Mustard ; Lepidium sativum, Garden Cress ; Nasturtium officinale, Water 



Fig. 479. — 1, Fruit of a Sili- 

 culosa lomentacm (Neslia 

 paniculata) ; 2, the same in 

 median, longitudinal sec- 

 tion. (After Wossidlo.) 



