Study of Morphology, Growth, and Flowering of Five Hoya Species from Borneo, Indonesia

Abstract

Hoya is a diverse tropical ornamental plant group widely distributed in Southeast Asia, with high species richness in Indonesia. Despite its horticultural and ecological importance, information on growth behavior and flowering characteristics of many species remains limited, particularly under new cultivation environments.This study evaluated the vegetative growth and flowering characteristics of five Hoya species from Borneo, Indonesia, in a new growing environment in East Java, Indonesia, over a 50-week observation period. Growth was assessed using leaf number, node number, primary branch number, and plant height. Hoya walliniana exhibited the most vigorous vegetative growth, with significantly higher increases in nodes, leaves, and branches, particularly after 20 weeks, while H. nabawanensis achieved the greatest plant height. In contrast, H. callistophylla and H. elliptica showed relatively minimal vegetative development. Flowering analysis revealed that H. latifolia did not flower during the study period. Among the four remaining species, H. walliniana and H. callistophylla reached anthesis more rapidly, and H. nabawanensis required the longest time. All flowering species showed a similar flower longevity of approximately 3 ± 1 days. H. walliniana produced the highest number of flowers per rachis, while H. elliptica had the largest floral structures. Overall, H. walliniana demonstrated superior performance across both vegetative and reproductive parameters, exhibiting the fastest vegetative growth and the highest flower production, indicating its strong growth potential under the growing conditions in East Java, Indonesia.