THALAMIFLOR.E loi 



this way equally suited to self- or cross-pollination. 

 Bees are the chief visitors. 



The outer coat of the seed is furnished with a layer 

 of mucilage. When wet this swells so that the seed 

 adheres firmly to the ground. Germination experi- 

 ments with mustard sown on flannel show this 

 feature well, and it is shown even better in the case 

 of cress. The siliqua opens when ripe, and the 

 seeds are jerked from the replum, or blown away by 

 the wind. 



The name mustard comes from the Spanish 

 Mastuerza ; the Latin nasturtium, or nasus, nose ; 

 tortus, twisted, from the pungency of the plant and 

 its effect. Mustard is grown in gardens as a salad 

 with Cress {Lcpidium sativum), or in fields near 

 Wisbech and elsewhere for the condiment. The 

 plant is ground up and mixed with water, when the 

 strong flavour comes out. The oil cake is used as 

 manure. 



Brassica alba. — Note in Fig. 13 the pinnatifid 

 leaves with rather broad segments. The raceme shows the 

 order of opening of the flowers ; the lower ones, after having 

 already opened, have been fertilised, and fruit has formed. 

 Those above are oben or in bud. 



Whitlow Grass (Draba verna). 



Diminutive or dwarf in stature, this little plant is 

 wide-spread, and is found in all parts of the British 

 Isles from the Orkneys to Cornwall, and in the 



