Floral traits
To understand the floral traits of H. mutabilis , 30 bagged flowers from 15 plants were examined on 10 October 2023. The Flowers are single- or double-flowered on a 5~8 cm pedicel on the upper branches (Fig. 1A). The H. mutabilis flower displays a color change from white to red (Fig. 1B). First, corolla diameter, corolla height, sepal length, sepal width, petal length, petal width, stamen length, pistil length, ovary height, and ovary diameter of each flower were measured with a digital calipre to 0.01 mm. The base circumference was measured by a thread, then the longth of the thread was determined by a digital caliper to 0.01 mm. The anther and ovule number of each flower were counted. To examine the production of pollen grains per flower, the anthers of each flower were dissected and washed in 400 mL of distilled water to dislodge the pollen grains from the anthers. The suspensions were stirred for 2 min, and three 1-mL samples of suspension were drawn respectively on the plankton counting chambers, after which the number of pollen grains in the samples was counted under a light microscope at ×10 magnification. the pollen count of the three sub-samples (1 mL each) was averaged and multiplied by the dilution factor (400) to obtain the total number of pollen grains per flower. To evaluate the production of nectar volume per flower (open one day), nectar volume was measured using 10-μL glass microcapillary tubes during the period of 17:00~18:00 p.m. on 10 October.