I've heard Hem-fir used different ways, so I looked it up.
Here, it is described as a group of similar trees:
Hem-Fir
"Hem-Fir is a species combination of Western Hemlock (Tsuga heterophylla) and five of the True Firs: California Red Fir (Abies magnifica), Grand Fir (Abies grandis), Noble Fir (Abies procera), Pacific Silver Fir (Abies amabilis), and White Fir (Abies concolor). While Western Hemlock and the True Firs are sometimes marketed separately in products graded for appearance, these species share similar design values making products graded for structural applications interchangeable."
Bruce
Here, it is described as a group of similar trees:
Hem-Fir
"Hem-Fir is a species combination of Western Hemlock (Tsuga heterophylla) and five of the True Firs: California Red Fir (Abies magnifica), Grand Fir (Abies grandis), Noble Fir (Abies procera), Pacific Silver Fir (Abies amabilis), and White Fir (Abies concolor). While Western Hemlock and the True Firs are sometimes marketed separately in products graded for appearance, these species share similar design values making products graded for structural applications interchangeable."
Bruce