Agave stalk
Thanks. Interesting looking things. Are the bushy structures flowers?
It is common in that lineage of plants. Fwiw that lineage is named for the asparagus, Asparagaceae, and most of those in that family have similar inflorescences.
Agave is split between between inflorescent traits, arborescent and spicate.
Arborescent is tree like with branching inflorescences like shown in your photo.
Spicate are simply spikes with little to no branching. Foxtail agave, Agave attenuata, is a good example shown below:

Sorry for the TMI dump.
Yes. They grow that stalk and flower and then die. The plant in the foreground will do the same one day.
Sure they die?
At least the agave on my windowsill grew one last year but is still totally alive and kicking right now...
Some species with flower repeatedly, some are growing for 30 years to build up enough energy to flower once and then they die.
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