Double fertilization results in the formation of  one diploid embryo and a triploid endosperm. Double fertilization is characterized by the formation of two embryos; the embryo proper which is diploid and the fusion product of the central cell with one male gamete which is triploid. This secondary triploid zygote develops into the endosperm. 
        
             
        
        
        
yes, coral polyps are a keystone species. it would be a keystone species because it is important in order for the coral to thrive.
 
        
             
        
        
        
Herbaceous mano it has vascular bundles arranged in a ring around the pit and herbaceous dicot stems has a vascular cambium between xylem and phloem
        
             
        
        
        
A theory that states that only the organism with traits that are useful to the environment survive. For example, short-neck giraffes would’ve died out years ago as they can’t reach the trees nor eat grass on the ground.
        
             
        
        
        
Fairly sure that would be secondary succession.