The final movement of the fourth of them opens with a descending scale before the folk-song "The Birch Tree" is quoted, while the piece ends in the key of F major.  The popular fifth begins with a theme introduced by the clarinets, while the third movement is a waltz, unusual for this kind of composition.  The last of them is a B minor work which premiered less than a month before the composer's death.  The first three have nicknames, such as "Winter Daydreams" and "Polish."  FTP, name this group of six orchestral works
The final movement of the fourth of them opens with a descending scale before the folk-song "The Birch Tree" is quoted, while the piece ends in the key of F major.  The popular fifth begins with a theme introduced by the clarinets, while the third movement is a waltz, unusual for this kind of composition.  The last of them is a B minor work which premiered less than a month before the composer's death.  The first three have nicknames, such as "Winter Daydreams" and "Polish."  FTP, name this group of six orchestral works by a Russian composer, the last of which is known as the "Path?ique."
The final movement of the fourth of them opens with a descending scale before the folk-song "The Birch Tree" is quoted, while the piece ends in the key of F major.  
the symphonies of Peter Ilitch Tchaikovsky (accept equivalents)