Grass tree look but all 3 different genera

[Al in Kona]

Three different plants with a similar grass tree look that are growing in the garden:

Xanthorrhea - Australian Grass Tree

Dasylirion longissimum - Mexican Grass Tree

Agave geminiflora

See pics below. Any way to tell which species or type the Australian Grass Tree is?

Pic (upper left) is the Mexican Grass Tree

[Al in Kona]

Here is the Agave geminiflora

[Al in Kona]

One more pic of the Australian Grass Tree to hopefully better see detail

[tropicbreeze]

You left out the genus Kingia. But it's not "The Australian Grasstree" in your photo. That could be any one of a number of Xanthorrheas, it's not easy to pick the difference.

[daxin]

One trick I learned is to bend a 4-5" section of the tip of a mature blade. If you can get it to form a semi-circle without snapping, the plant is Xanthorrhea. Dasylirion will snap. Don't know if this applies to Kingia as well. That plant is ultra rare in the US

[daxin]

There are also several Nolina with the grass tree look. Their blades are always serrated