Colony Growth and Development in an Epiphytic Fern Species, Platycerium Bifurcatum.

<p><strong>Cooperation is one strategy that can allow organisms to thrive in often harsh environmental conditions. While it is well understood in animals, it is much less understood in plants. The Australian staghorn fern (Platycerium bifurcatum) is an epiphyte that forms large colonial nests commonly found on the branches and trunks of trees. Recent research has uncovered how the varying frond morphology in colony members facilitates task specialization in staghorn colonies, similar to the task specialization observed in complex animal societies. However, we know nothing about their colony growth and development. Here, I create a graphical model of colony ontogeny based on four model predictions and investigate the patterns in growth and development through a series of four experiments. Key findings support the hypotheses that new colony members establish below older members, apical growth orients upward, and the oldest, largest members are located near the top of a colony. New rhizomes oriented in a moderate downward direction (132°), while growing tips orient upward (20°) over time. Rhizome size (primarily length and volume) and age increased significantly with vertical position in the colony. This research provides evidence for clear patterns in colony growth and development, and offers a foundational understanding on how colonies grow and develop in a structured way. Questions are raised about individual ramet growth patterns, the adaptive nature of observed traits, and the interplay between plasticity and evolution in shaping colony structure.</strong></p>