什么是自花传粉？什么是异花传粉？植物如何在花部的形态结构和生理上避免自花传粉发生？

At the invitation of President George W. Bush, I will be attending and actively participating in the Group of Eight meeting this week in Sea Island, Georgia. The G-8 nations have rightly identified African development, AIDS, global peace and security, private sector-led growth and the alleviation of poverty through greater trade as the essential issues concerning the world and Africa in particular. I agree with this assessment. But this year I come to the G-8 .meeting to convey a new sense of urgency in our collective work. On Thursday, I plan to support five tangible proposals for the G-8 that I deem globally urgent, highly practical and wholly feasible, with results that will be quickly measurable. We must identify and reduce the unintentional waste of foreign aid that happens through poor procedures, duplication and flawed management. We must initiate a "counter-brain drain." For decades, developing countries have been educating and training highly skilled individuals and managers, who systematically leave their countries — the countries that so desperately need them — and become absorbed in the economies of developed countries. We should begin to issue "business passports" based on the economic activities of individuals, not on citizenship or nationality. We need to endorse and organize a world conference for Islamic-Christian dialogue within the next six months. We can remove corruption, while increasing efficiency at the same time. The allocation of resources to our nations today takes a painfully long time. But the handicap of delays can be avoided. The president of the World Bank, James Wofensohn, once said that an African country that expresses the need to realize a project — a road, for example — has to wait at least five years. Five years is too long. In Africa, we die waiting. I am not attending the G- 8 meeting in search of funding or handouts, but to propose and support what we need most — dynamic ideas that can be implemented without delay. I start with these five.