Reproductive biology and propagation of Magnolia caricifragrans (Lozano) Govaerts, an endangered species from Colombia

Background: M. caricifragrans is an endangered tree species. Around 50 isolated trees grow in highly altered landscapes in the cloud forests of the states of Cundinamarca and Tolima (Colombia). Questions: How is the reproductive phenology of M. caricifragans in individuals under ex situ conditions? Can M. caricifragrans produce seeds with the aid of hand pollination? Are seeds issued form hand pollination viable? Who are the flower visitors of M. carcifragans under in situ conditions? What is the survival rate of the plantlets in the field after reintroduction? Sites and years of study: Bogotá Botanical Garden “José Celestino Mutis” from 2019 to 2022 and in the municipalities of San Francisco and Silvania. Methods: We monitored reproductive events one year in ex situ conditions, including manual pollination, fruit development, and seed germination. We also captured floral visitors from wild M. caricifragrans flowers. Seedlings reintroduced into nature reserves and survival was evaluated. Results: Trees ex situ exhibit constant flower bud and flower production throughout the year and do not produce fruit. Fruits with viable seeds that germinated were obtained through hand-pollination. In situ flower visitors consisted mainly of roving beetles; twenty-seven seedlings were successfully reintroduced. Conclusions: A peak of flower production was determined between September and November, successful fruit development by controlled cross-pollination. Seed germination was achieved using a closed container with a substrate with high moisture retention and good drainage. Trees reintroduced in nature present a healthy development and 100 % survival.