GRE阅读 昆虫帮助苏铁传粉最后一道阅读题解析

阅读原文：Experiments show that insects can function as pollinators
of cycads, rare, palmlike tropical plants. Furthermore,
cycads removed from their native habitats—and therefore
from insects native to those habitats—are usually infertile.
Nevertheless, anecdotal reports of wind pollination in
cycads cannot be ignored. The structure of cycads male
cones is quite consistent with the wind dispersal of pollen,
clouds of which are released from some of the larger cones.
The male cone of Cycas circinalis, for example, sheds
almost 100 cubic centimeters of pollen, most of which is
probably dispersed by wind. Furthermore, the structure of
most female cycad cones seems inconsistent with direct
pollination by wind. Only in the Cycas genus are the
females' ovules accessible to airborne pollen, since only in
this genus are the ovules surrounded by a loose aggregation
of megasporophylls rather than by a tight cone.