Ph.D. Candidate & Research Assistant
Rancho Santa Ana Botanic Garden
1500 N. College Avenue
Claremont, CA 91711-3157
Systematics and Floral Trait Evolution in Justicia (Acanthaceae)
The ‘justicioid’ lineage includes members of pantropical Justicia, the largest genus in
Acanthaceae (ca. 600 spp). The floral morphology in this lineage, including size, color, and inflorescence structure are remarkably diverse, mirroring that of the entire family. In addition, Justicia is particularly intriguing because among Acanthaceae, it is the only group that demonstrates remarkable variability in anther morphology: the two stamens may have thecae that are parallel, equal and unappendaged or that have expanded connective tissue resulting in thecae displacement and appendages. My research strongly suggests that anther morphological disparities are correlated with pollination syndromes. New World Justicia with hummingbird pollinated flowers often have anther thecae that are parallel, or nearly so, whereas Justicia from the Old World, where hummingbirds do not occur, lack this arrangement. Insect pollinated Justicia from both hemispheres tend to have highly modified anthers with expanded connective tissue, often with spur-like structures and varying degrees of super-positioning of the thecae. I am applying both morphometric and molecular evidence to elucidate species relationships and trait evolution in this diverse group.
Pollinator-mediated selection on floral traits has been considered a major driving force of floral diversification and speciation in plants. In addition to color and fragrance, floral structures such as petals, anthers and pollen can contrast markedly between closely related species. These morphological differences are often hypothesized to be associated with pollinator adaptation. Because flowers, and in particular anthers, mediate the plant-pollinator interface, my research is important to understanding how floral structures may change in response to pollinator-applied selection. In addition, this study will inform our understanding of floral diversification and conservation strategies, especially in species-rich neotropical groups like Justicia where pollinators have unquestionably been an important selective force.
For more information on Acanthaceae: http://www.tolweb.org/Acanthaceae