十万个为什么·科学阅读30篇（2）

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为什么某些沙漠植物只在罕见的大雨后才开花？

Desert plants like the desert lily or ocotillo have seeds that remain dormant for years until heavy rain arrives.
Their seeds possess chemical inhibitors that prevent germination unless washed away by sustained rainfall.
Soil moisture must penetrate deep enough to reach buried seeds and trigger metabolic activation.
Some species even require specific temperature drops after rain to break dormancy fully.
Blooming happens quickly — often within days — to maximize seed production before soil dries again.
This 'boom-and-bust' strategy avoids wasting energy during long dry spells with no pollinators.
Flowers attract short-lived insects and birds that also appear only after rain renews resources.
Researchers use satellite data to predict bloom events by tracking rainfall patterns across arid zones.
The timing ensures cross-pollination success while minimizing competition with non-desert species.
Such adaptations reveal how evolution shapes life to match unpredictable environmental rhythms.