Fig. 2.

Reproductive success of hand-pollinated flowers that were and were not augmented with Agave palmeri pollen. Addition of A. palmeri pollen had no effect on fruit set (A) or mean (± s.e.m.) seed set per fruit (B). In contrast, as in the earlier experiment whose results are shown in Fig. 1, flowers receiving outcross pollen set significantly more fruits and seeds per fruit than those that were autonomously pollinated. Abbreviations: aut SP, autonomous self-pollination, from unmanipulated flowers; hand OP, hand outcross-pollination, i.e. from flowers on which pollen from other plants had been actively deposited; aut SP + Agave, flowers on which A. palmeri pollen alone was actively deposited; hand OP + Agave, emasculated flowers to which both outcross D. wrightii and A. palmeri pollen were actively deposited.