Steward Avocado  A flower type  

Picked this up form a web site:
The "Stewart" avocado tree (Persea americana "Stewart") is more frost-resistant and cold-hardy than some other avocado tree varieties. "Stewart" avocados are cold-hardy to 24 degrees Fahrenheit and grow in U.S. Department of Agriculture plant hardiness zones 9 and 10. The tree grows about 30 feet tall, and has small, dark purple fruits that ripen in late fall. Avocado trees need full sun and rich, well-draining soil. Protection from wind is also beneficial; the trees are somewhat brittle.
In some places they refer to it as a Mexicola type tree. My interest in this fruit is because of flower type and my quest for pollinators to fit an specific time frame. 

A tree was grafted in early 2014 it is doing well.
May 18, 2015: The tree set quite a few fruits on its first flowering. Does not seem like the smooth skin of the Mexicola.