Choka, a form of waka (Japanese poetry of the 6th to 14th century) consisting of alternating lines of five and seven syllables and ending with an extra line of seven syllables. The total length of the poem is indefinite. Waka, Japanese poetry literature, includes many other forms as the ch¿ka. The ch¿ka, "long poem," is of indefinite length, formed of alternating lines of five and seven syllables, ending with an extra seven-syllable line. The shortest of those extant are 7 lines long, the longest have 150 lines. The amplitude of the ch¿ka permitted the poets to treat themes impossible within the compass of the other versions. Ch¿ka are unique in Japanese poetry thanks to their superb combination of imagery, syntax, and emotional strength. The most striking quality of the poetry is its powerful sincerity of expression. The poets were certainly not artless songsmiths exclaiming in wonder over the beauties of nature, but their emotions were stronger and more directly expressed in poetry.