Though a common occurrence in parts of the southwest, century plants (Agave sp.), blooming in Denver are rare. Most years there is one blooming somewhere in Denver and we all take trips to visit it and marvel at the huge flower spike. This year we are lucky enough to have three blooming here at the Gardens.
Ok, so only one is the insanely tall (about 18 feet) flower spike of Agave parryi ssp. neomexicana. Located in the Rock Alpine Garden it is impressive due to its size alone; that and the speed with which it grew - it reached it full height in a couple of months.
Agaves only bloom once in their lifetime and they use so much energy to do it that they die afterward. They are called century plants as it is believed they only flower once every 100 years - this is not strictly true, they can really bloom anywhere from about 10 years onwards depending on species.
Though not as impressive in size the other two are interesting for their rarity. Until now Agave parryi ssp. neomexicana is the only agave I have ever seen bloom in Denver. Also in the Rock Alpine Garden is Agave virginiana (sometimes known as Manfreda virginiana). This is the smallest of the bloom spikes reaching only four or five feet. It has an interesting flower form consisting mainly of stamens and stigmas with very little to see for petals.
The third, on top of Dryland Mesa, is either a hybrid between Agave lechuguilla and Agave parryi ssp. neomexicana or an Agave lechuguilla from New Mexico with an unusual form. Either way it is an unusual plant in itself and it is a little sad that it is blooming, despite the temporary excitement, as it has not produced any pups (baby agaves) to live on after it is done. This spike is only about seven feet tall, still pretty impressive for the size of the plant and oddly there is a small three inch flower spike popping out of the ground next to the main plant (see photo above) - I have seen some pups bloom when the mother plant does in a similar way; I can only guess that whatever it is that triggers the plant to grow is in such abundance that it spills into another part of the plant causing the same reaction - if anyone knows more about this phenomenon please let me know.
Make sure to check all three out soon as they are in peak bloom right now.