Floral Biology of Thalia Dealbata (Marantaceae)

Undergraduate #26
Discipline: Biological Sciences
Subcategory: Plant Research
Session: 3
Room: Marriott Balcony A

Iran Williams - Harris- Stowe State University
Co-Author(s): David Bogler, Ph.D., Harris- Stowe University Missouri Botanical Gardens

Thalia dealbata is an emergent aquatic plant in family Marantaceae, order Zingiberales (which also includes canna, bananas, ginger). It occurs in ditches and lakes in the south-central U.S., reaching southeastern Missouri. The flower structure is very unusual, and the objective of this study was to carefully observe flower morphology to uncover clues to the pollination biology and test whether the flowers are self-pollinating when pollinators are excluded. Flowers are borne in borne in mirror-image pairs in compact clusters with a zigzag rachis and sheathing bract. The showy parts are purple petaloid staminodes. The androecium is reduced to a single half-anther. The style is curved, turgid, and held under tension. Insect visitors trigger an abrupt style movement. The elaborate structure and tripping mechanism suggests the possibility of a “lost pollinator”. The following floral features were dissected and studied: flower arrangement, ovary position, sepals and petals, petaloid half-anther and staminodes, curved style with stigmatic pouch, fruits, seeds, and fleshy aril. The most common visitor is the Carpenter Bee (Xylocarpa virginica). They are large enough to trip the elastic style, and continue to visit tripped flowers to get at the copious nectar. To test for autogamy (self-pollination), all open and visited flowers were picked off inflorescences and the remaining flowers were bagged for later observation to see if fruits developed in the absence of pollinators. No fruits developed so we infer that T. dealbata requires pollinator activity to set seed.

Funder Acknowledgement(s): National Science Foundation; HBCU-UP Implementation Grant HRD-0811219

Faculty Advisor: David Bogler Ph.D., david.bogler@mobot.org

Role: I examined Thalia dealbata under a microscope and I did multiple dissections of Thalia dealbeta. I recorded the activity between Thalia dealbata and the Carpenter Bees.