FLORAL DISPLAY IN PHYLA INCISA: CONSEQUENCES FOR MALE AND FEMALE REPRODUCTIVE SUCCESS

Area of Science:

• Botany
• Ecology
• Plant Reproduction

Background:

• Phyla incisa inflorescences exhibit flowers in two distinct phases: younger, nectar-producing yellow-throated flowers and older, nectarless dark purple-throated flowers.
• Understanding the differential roles of these flower phases is crucial for comprehending pollinator attraction and reproductive strategies in this species.

Purpose of the Study:

• To investigate the role of younger and older flower phases in attracting pollinators to Phyla incisa inflorescences.
• To determine the impact of older-phase flowers on both male (pollen removal) and female (pollen deposition) reproductive success.
• To analyze pollinator visitation patterns in relation to inflorescence size and flower phase composition.

Main Methods:

• Observing pollinator visitation patterns on natural and manipulated Phyla incisa inflorescences.
• Quantifying pollen removal from and deposition onto stigmas of inflorescences with varying proportions of older-phase flowers.
• Comparing pollinator preference for inflorescence size against availability.

Main Results:

• Pollinators preferentially visited larger Phyla incisa inflorescences.
• Both younger and older flower phases attracted pollinators, though older phases were less effective individually.
• Older-phase flowers significantly increased inflorescence visitation rates and pollen removal but had minimal impact on stigma pollen deposition.
• Pollen deposition on stigmas was stochastic, while pollen removal was more consistent.

Conclusions:

• Older-phase flowers contribute to pollinator attraction and enhance pollen donation, particularly when pollinator activity is high.
• Retention of older-phase flowers may improve seed set probability, especially during periods of low pollinator abundance.
• The study highlights a complex interplay between flower phenology, pollinator behavior, and plant reproductive outcomes in Phyla incisa.