4 THE BROAD BEAN PLANT. 



The Broad Bean is commonly cultivated for its large edible seeds, 

 and (like most cultivated plants) =hows several varieties (Longpod, 

 Mazagan, etc. ), differing in such details as shape and size of pod and 

 seed and in times of flowering. A common and distinct variety is 

 the Field or Horse Bean, of which the seeds are used chiefly for 

 feeding horses, the ' ' straw " for stabling purposes ; its seeds are 

 much smaller and less flattened than those of the typical Windsor 

 Broad Bean. 



Dig up an entire Broad Bean plant in the garden (or the very 

 similar Horse Bean grown in the fields), and free the root from the soil 

 that clings to it by shaking it to and fro in a pailful of water and after- 

 wards washing under a stream of water from a tap. Set the plant in a 

 basin bf clean water, so as to allow the branching root to spread out, 

 as well as to prevent its drying up. 



If complete flowering and fruiting Broad Bean plants cannot be 

 obtained at once, begin by studying the seed and its germination 

 (Art. 31 and rest of this chapter ; Ch. II.). Make successive sowings 

 in the garden, also in pots and boxes, so as to get abundant material, 

 in the form of seedlings, to start work with. 



8. The Root consists of a main downward-growing axis 

 (continuous with the upward-growing axis or stem), from 

 which arise branches that spread out from it. Are these 

 first branches horizontal or not ? Do they all make the same 

 angle with the main root ? These first branches give rise in 

 their turn to finer branches ; in what directions do these grow 

 in the soil, and how many times may the process of branching 

 be repeated? Compare the different directions of growth 

 taken by the main axis and by the successive sets of branches. 

 Do these differences help the root to come into contact 

 with as much soil-space as possible in the most economical 

 way? 



9. Rootlets. Are the first branches scattered irregularly over the 

 surface of the main root? To make out their arrangement, cut out 

 a straight piece of main root, about 6 ins. long, cut off the branches 

 about half an inch from their origin, and look along the piece 

 from end to end. Sketch the piece, showing the rows of branches 

 arranged along the axis. This arrangement can easily be made out in 

 seedlings. In the Broad Bean the side-roots are usually in 5 rows on 

 the main root ; in the Scarlet Runner and the French Bean there are 

 usually 4 rows, arranged with great regularity on the main root. 



Examine closely the place where a branch (rootlet) leaves the parent- 

 root. Is the surface smooth and continuous, or is there anything 

 visible that suggests the way in which the branch arose from the 

 parent-root ? What further information is gained by cutting across 



