This flower looks like a miniature greenish brown rose, even though it is a flower rather than a bush. This small plant has small stinging nettles along its spine instead of thorns. (98% of people are allergic to the nettles to some degree). The leaves are small and jagged. The flower has little to no smell of its own, but since it only grows in decomposing middin (including offal piles, old latrines, decomposing animals or plant matter), few notice that fact.
Since Orcs tend to live in and around large amounts of middin, ofal, and blood pools, the flowers have become associated with them. (Orc tribes actually spread the spoors as they migrate) In fact, the presence of Orc Roses in an area often shows that Orcs have been, or are, in the area.
Note other Goblinoids tend to have Orc Roses around them as well.