Chin J Plant Ecol ›› 2011, Vol. 35 ›› Issue (12): 1290-1299.DOI: 10.3724/SP.J.1258.2011.01290

• Research Articles • Previous Articles     Next Articles

Intra-inflorescence sex expression and allocation in Camptotheca acuminata

XU Shen-Lin, LIU Wen-Zhe*()   

  1. Laboratory of Resource Biology and Biotechnology in Western China of Ministry of Education, College of Life Sciences, Northwest University, Xi’an 710069, China
  • Received:2011-05-17 Accepted:2011-11-07 Online:2011-05-17 Published:2011-12-15
  • Contact: LIU Wen-Zhe


Aims Variation in intra-inflorescence sex expression and allocation is a common phenomenon in Angiosperms. The typical pattern is that the size and number of reproductive structures decrease from early to late blooming flowers within the same inflorescence, and the late ones tend to male. Resource competition and architectural effects are regarded as the main causes of these variations. Within the cyme of Camptotheca acuminata, the early capitula demonstrate more significant differences in the diameters of capitulum and corolla, length of short stamen, fruit set rate, and infructescence mass than the late capitula. Our main objective is to determine the causes behind the intra-inflorescence sex expression and allocation variations in C. acuminata.
Methods The distribution of resources within inflorescences of C. acuminata was manipulated by removing the primary or primary and secondary capitula to determine the factors influencing flower sex allocation and reproductive capacity in an inflorescence.
Important findings After removing part of the capitula, the diameters of capitulum and corolla in the remaining capitula increased significantly, the length of short stamen decreased significantly, and the differences between positions disappeared. The differences, however, in fruit set and infructescence mass remained unchanged. This suggests that resource constraints rather than architectural effects have stronger influence on the diameters of capitulum and corolla as well as the length of short stamen, while architectural effects play a dominant role on fruit set and infructescence mass. The andromonoecy in C. acuminatamay be the result of adaptation to specific reproduction and resources competition.

Key words: architectural effects, Camptotheca acuminata, intra-in?orescence variation, resource competition, sex allocation