Plant Communities of the World 269 



species together form dominance; the most prominent are 

 Pentaclethra macroloba, Licania venosa, Licania laxiflora, Li- 

 cania heteromorpha perplexans, Eschtveilera sagotiana, and 

 Ocotea rodioei, followed by about eighty-five less plentiful 

 canopy-tree species. The majority of these are the same as in 

 the Morabukea and Greenheart types. Ocotea rodioei, the Green- 

 heart, dominates the next type, growing on reddish brown 

 sand ''reefs!' The most distinctive type, structurally and flor- 

 istically more sharply distinguished from the other types than 

 they are from one another, is the Wallaba association dominated 

 by Eperma falcata, growing on the white sand of the high hill- 

 ridges. The number of trees to the unit of area is very large; big 

 trees are scarce; buttressing is almost absent. From the Blue 

 Mountains of Jamaica, Shreve gives an account of montane rain- 

 forest with three dominant species — Clethra occidentalism Vac- 

 cinium meridionale, Podocarpus urbanii — which make up half 

 the tree canopy. 



2. Pluviifruticeta: Rain scrub. — Pluviifruticeta are scrubs rich 

 in epiphytes whose dominant plants consist of evergreen shrubs, 

 usually without bud protection and with glabrous and glossy 

 foliage. Climatically there is no reason why scrub instead of 

 forest should prevail. Edaphic and biotic checking cause scrub 

 under the same tropic climate. Rain scrub is very limited. In the 

 flood region of tropic shores lives the characteristic Mangrove 

 of shrubs and small trees. Karsten writes about them: Root 

 sprouts break forth from the stem and from the lower branches 

 and reach, in an elegant bend, the soil; the stem of the Rhizo- 

 phores dies away and the "tree" stands only on its stilt roots — 

 a very curious sight. So in spite of a short trunk these "trees" 

 are positively of shrub rank. At high tide only the crowns are 

 visible, at low tide one sees them standing on a dense tangle of 



