PEA 25 



gives off lateral branches, while the shoot grows up into the air 

 and light. The seed leaves remain beneath the soil in the seed- 

 coat, and are gradually depleted of their food material. The 

 plant grows up rapidly from the seedling and attains a considerable 

 height, which differs in the numerous varieties of this extensively 

 cultivated plant. The Pea is an annual plant bearing flowers 

 and fruiting in its first season and then dying. The seeds are left 

 to carry on the race in the next year. 



The root system of the Pea consists of the tap-root and its 

 lateral branches, which in turn branch. It calls for no special 

 description, save to refer to the nodular swellings found on some 

 of the finer branches. Similar nodules or root- tubercles are found 

 in most of the plants belonging to the same family as the Pea, and 

 have been mentioned in describing the Bird's-foot Trefoil. These 

 swellings are inhabited by innumerable minute Bacteria, the 

 association of which with the plant enables it to utilise as food 

 the nitrogen which forms a large proportion of the air. Ordinary 

 green plants are unable to do this, and depend for this important 

 constituent of their food upon nitrates and other nitrogenous 

 compounds in the soil. 



The shoot of the Garden Pea consists of the stem bearing 

 large leaves of complicated form and construction. These are 

 inserted singly at the nodes and separated by fairly long internodes. 

 Each leaf stands on the opposite side of the stem to the one 

 immediately below. The stem itself is somewhat flattened, so 

 that the cross-section is oval and not circular. Cutting the stem 

 across also shows that it is not solid, but is traversed by a central 

 cavity, which is not interrupted, as in many plants, at the nodes, 

 but continuous throughout the length of the stem. The surface 

 of the stem and leaves is quite smooth and free from hairs, but is 

 covered with a " bloom " such as is familiar in many fruits. As 

 in these, the bloom is due to a covering of minute particles of wax, 

 and can be readily removed by rubbing the surface with the 

 finger, when the greyish-green tint disappears. 



The leaves are compound. The leaf-stalk gradually tapers, 

 and bears pairs of leaflets ; it ends in a thin cylindrical struc- 

 ture known as a tendril. Below this are one to three pairs 

 of similar tendrils. Lower down still we come to two or three 



