THE DICOTYLEDONES 



^739 



is unusual. The first four nuclei formed are large and tetrahedrally grouped. 

 From these sixteen nuclei are formed, one of which, at the micropylar end, 

 forms the oosphere, while one adjacent nucleus functions as a synergid. 

 Eight of the remaining nuclei unite after fertilization to form the primary 

 endosperm nucleus. The remaining six preserve their parietal position 

 and finally become enclosed in walls. There are no definite antipodal 

 cells. It will be noted that there is a similarity between this and the beha- 

 viour in the embryo sac of Gnetum. 



The plant of chief economic importance belonging to this family is 

 Piper nigrum, a member of a large genus of some 700 species. It is a weakly 

 growing climber, a native of Indo-Malaya where it is chiefly cultivated. 

 It is propagated by cuttings, planted around live trees which serve as 

 supports. These cuttings take about three years to reach a length of 15 ft. 

 and are in full fruit for about six years thereafter. The berries are borne 

 in clusters of about thirty. They are green at first, turning successively 

 red and finally yellow when ripe. When they reach the red stage they 

 are picked, spread out in the sun, and rapidly turn black. These berries 

 when ground form the black pepper of commerce. 



White pepper is made by soaking the black berries in water for several 

 days till the outer coat can be rubbed oflF. 



Several other species of Piper are in cultivation (Fig. 161 7). P. longuni 







-v^-";^i\---'^l,S^ 



Fig. 1617. — Piper iiduiuniu. Brazil. 



is similar in appearance to P. nigrum and grows more quickly; the berries, 

 however, are not so pungent. It is chiefly cultivated in India. P. betle is 



