Assessing the Invasive Potential of Lantana Camara Polyploids Based On Controlled Pollination

Invasive plants have become a major concern because of their ability to spread, displace native plants, and alter ecosystems.  In Florida the native species Lantana depressa has been threatened by Lantana camara that can pollinate the native and contaminate the native gene pool.  Polyploids have been selected over the past decades in hope to reduce L. camara's potential to cross-pollinate L. depressa.  This study was conducted to assess the effectiveness of polyploidization on reducing such potential. Thirty-two L. camara polyploids, including 17 triploids, 10 tetraploids, two pentaploids, and three hexaploids, were used, and the control was three L. camara diploids.  Controlled pollinations were performed in the greenhouse and seed set data were recorded. Results indicated that L. camara diploids were highly compatible with L. depressa.  L. camara tetraploid, pentaploid, and hexaploids effected less seed set with the native than diploids, but most of the polyploids were still able to pollinate L. depressa and produce viable seeds.  Although pollination of L. depressa with most of the triploids did not result in seed set, some triploids seemed able to produce viable pollen and cause seed set on L. depressa.  Reciprocal crosses were also made to assess the potential of L. camara polyploids to produce seeds when pollinated by L. depressa.  Overall, higher seed set percentages were observed when polyploids were the seed parents (L. camara x L. depressa) than when they were the pollen parents (L. depressa x L. camara). These results indicate a strong need to produce and test triploids for controlling L. camara's invasive potential.