This poem from Clark Ashton Smith (CAS) was included in a group of "quintrains" in Spells and Philtres (1958). The same grouping of poems was also included in his omnibus Selected Poems (1971). Quintrain is apparently CAS' own word; the more usual term for a five-line poem is quintain.
"Essence" is available on The Eldritch Dark with the alternate title "Attar of the Past":
It's a lovely little poem, and in less than twenty words captures a feeling inspired by the season after the rose flowers have wilted and dropped their petals. From the crushed remains of those petals arises the hint of their fragrance.
CAS could be both an expansive poet and a concise one; "Essence" shows that he had fully mastered the latter approach.