Tatsutagawa iro kurenai ni narinikeri yama no momiji zo ima wa chirurashi - Gosen Wakashu(English Translation & Meaning)

竜田川色紅になりにけり
山の紅葉ぞ今は散るらし

Roma-ji: Tatsutagawa iro kurenai ni narinikeri yama no momiji zo ima wa chirurashi
English Translation: Tatsuta River
has turned crimson in its hue—
now on the mountains
the autumn leaves, it would seem,
are falling into the stream
Meaning: The Tatsuta River has turned crimson; it seems the autumn leaves on the mountains are falling now.
Commentary: Book Seven Autumn Poems III 413

Headnote: "Topic unknown."
The poet says that the water of the Tatsuta River has turned crimson, and surmises that the leaves on the mountains upstream must now be falling. From the river's change of color, it infers the unseen scattering of the leaves in the hills.
From 413 to 416 of this book, poems follow one another on autumn leaves flowing down rivers. Ariwara no Narihira's poem in the Ogura Hyakunin Isshu, "chihayaburu kamiyo mo kikazu Tatsutagawa karakurenai ni mizu kukuru to wa," also sings of the Tatsuta River dyed by autumn leaves.
The poet is listed as "anonymous," and the composer's name has not come down to us.

The first line, "Tatsutagawa," is the river flowing at the foot of Mount Tatsuta in Yamato, famous for its autumn leaves. The next poem and 416 also open with "Tatsutagawa."
The second line, "iro kurenai ni," means "crimson in color."
In the third line, "keri" expresses realization: "it has become so." The poem pauses here.
The fourth line, "yama no momiji zo," means "the leaves of the mountains," with "zo" a binding particle.
In the last line, "rashi" is an auxiliary of grounded inference: "they seem to be falling now," inferred from the river's change of color.
Author: Unknown Poet
Source: Gosen Wakashu
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Next Poem: Tatsutagawa aki ni shi nareba yama chikami nagaruru mizu mo momiji shinikeri