Ecological Significance of Bi-Seasonal Flowering and Fruit-Setting ofTamarix ramosissima

Abstract

The flowering biology and seed germination ecology of Tamarix ramosissima were studied in the deserts of Xinjiang, China. Several significant characteristics were found: (1) Tamarix ramosissima flowers twice a year, with separate spring and summer flowering periods. (2) The spring flowering period is shorter, for only 10 days, forming a “mass-flowering pattern”; the summer flowering period is longer (45 days), forming an “extended-flowering pattern”. (3) Both the spring flowering period and the summer flowering period have short fruit-setting periods (14 days), quickly producing seeds, forming characteristic extended-flowering and extended seed-spreading patterns. (4) Under natural conditions, the plant has higher fruit setting and seed setting rates during the spring flowering period than during the summer flowering period; there is no significant difference in external morphological characteristics, such as size or weight, between seeds from the two flowering periods. (5) Freshly harvested seeds from both flowering periods can germinate at four thermoperiods with germination rates both higher than 80%. The annual bi-seasonal flowering and fruiting characteristics of T. ramosissima allow it to respond to temporal and spatial variations in the desert environment, thereby increasing its chances of survival as a species in its harsh desert habitats.