The outer petals of red parrot tulips are streaked with green.
In a French dictionary the word roucoulement is defined with the help of the phrase- le roucoulement de tourterelles. This reminds me of the example of onomatopeoia which we were given at school in Tennyson's phrase, "the moan of doves in immemorial elms". But roucoulement isn't exactly "moan", more "coo", less melancholy and not nearly so poignant. Le gémissement de colombes en ormes immémorials, might do. But Tennyson and English has it, just. Oh what a tangled web we weave when first we practice to translate!