This is one of two poems with the same title from Clark Ashton Smith (CAS). This particular poem was unpublished in the author's lifetime, and is not available at The Eldritch Dark, so here's the complete text:
Templed beneath unmoving skies,
From saffron unto red aspire
The trees with unconsuming fire
Of Autumn's smokeless sacrifice.
While zephyrs tell her sacred name,
I find a little time to kneel,
Ere lightless Winter's silent heel
Stamp out the smouldering altar-flame.
This is another excellent nature study from CAS, providing a contrast to his better-known poems of the cosmic and the weird. The image of "Autumn's smokeless sacrifice" is exquisite, and perfectly echoed by the ending phrase "the smouldering altar-flame".
I often wonder what greater recognition as a poet CAS might have received if his reputation was not based primarily on his short fiction. Although poetry in general lacks widespread cultural impact in the modern era, it's also a fact of life that writers of genre fiction tend to be dismissed as serious artists.
I love many of CAS' works of fiction, but poems like "Autumn Orchards" are strong enough to warrant notice on their own merits, regardless of the author's other literary pursuits. I suppose it's best to just read and enjoy, and not spend too much time thinking about what might have been!