Desert Annuals

Desert annuals demonstrate sophisticated environmental sensing. Some can detect rainfall duration and intensity - a light shower activates initial water uptake but isn't enough to sustain a seedling through desert summer. Seeds may require multiple wetting-drying cycles or sustained moisture before committing. Some wait for three rainstorms totaling 25mm over two weeks - that specific pattern predicts enough moisture to complete a 6-week lifecycle. Seeds can remain viable for decades, waiting for once-per-decade rains.