Update 4/19 The side stalks have spread out from the main stalk. We should have blooms soon. By the way, if it looks like a giant asparagus, that is because it is. Agaves are in the asparagus family.
If you spend much time in Chino Hills SP, you have likely seen the large agave growing at the very western end of Telegraph Canyon. The agave is doing its once in a lifetime bloom. We saw the beginning of the main stalk on March 7 and now the very first signs of the flowering side stalks have appeared. After the bloom, the plant dies. So, this is a relatively rare event. See it if you can. Here are some pictures.
March 7
March 14
March 21
March 28
April 4
April 11
Beginning side stalk