Juglans jamaicensis a newly grown shoot. The fruit is a drupe roughly 2 to 3 centimeters long with a black husk and a seed, which is an edible walnut meat, inside. In Puerto Rico there are only ten to fourteen trees of this species remaining. It is also rare in Cuba and Hispaniola. It is threatened by habitat loss. It may never have been common, but specimens were likely lost when forest was cleared for coffee plantations on Puerto Rico, and it was probably harvested for wood. The attractive wood is similar to that of the black walnut ("Juglans nigra"). This tree
Two-sided market to invest more in R&D or lower their prices, driving out weaker rivals. As a result, mature two-sided network industries are usually dominated by a handful of large platforms, as is the case in the credit card industry. In extreme situations, such as PC operating systems, a single company emerges as the winner, taking almost all of the market. Platform managers must choose the right price to charge each group in a two-sided network and ignoring network effects can lead to mistakes. In "figure 2", pricing without taking network effects into account means finding prices that maximize the areas of