It was found that the bud bracts filled with dense pubescence of most plants in high altitude at low temperature in early spring was morphological characteristics during the investigation of the Pan-Himalayas plants.By study on the Salix,the relationship between dense of pubescence on bud bracts and the altitude was discussed;the temperature changes of inner and outer buds were observed by using infrared thermometer and infrared thermal imager,and temperature of Magnolia flower buds which located in temperate regions was measured under the light of the sun or overshadow conditions.In addition,the inside and outside temperatures of Salix flower buds and Magnolia flower buds in different light intensity were compared by using Li-6400 XT portable photosynthesis system,and the relationship between the intensity of light and temperature changes of flower buds was studied.(1)It was indicated that the dense of pubescence on bud bracts are related to altitude and light intensity,and the higher the altitude,the denser pubescence on bracts,for the pubescence on buds bracts absorbed heat in the sunlight.(2)The pubescence play a role in keeping the internal of buds warm,and to prevent the young flower bud in winter or early spring from cold.It led us to extend the concept to a larger group of plants,namely “pubescence plants”,which are characterized by very dense pubescence on tightly packed bracts of buds or inflorescences.It was indicated that this character is a result of a convergent adaptation for low temperature in early spring.