STRATIFICATION OF POLLINATION SYSTEMS IN A SHRUB AREA OF THE VENEZUELAN GUIANA

Floral biology, pollination mecanisms and the pollination system are r eviewed in relation to the spatial organization of vegetation in a mes otermic shrubland community (Venezuelan Guayana). There was no tempora l variation of the reproductive structure in 55 plant species consider ed at three vertical strata. Most flowers were white, greenish and oth er pale colors in the first (0.0 - 0.5 m) and third (2.7 - 6.0 m) leve ls. The 0.5 - 2.7 m level had the highest diversity of flower color. T here was no significant variation in flower size in relation to height . At all levels bees were the main pollinators; birds pollinated only at the second. Body size of insect pollinators was not correlated with heigth. The proportion of pollinators specialized in one stratum was higher in the second level. Non pollinating visitors were exclusive to one stratum. Pollinator specificity and pollination system specificit y were independent of height. Pollinator specificity and pollination s ystem specificity were not correlated with the density, frequency and population disposition of the plants. The number of pollinators per pl ant was correlated with the plant species frequency.