Pines of Rome (Italian title: Pini di Roma ) is a four-movement tone poem for orchestra completed in 1924 by the Italian composer Ottorino Respighi.
 The piece, which depicts pine trees in four locations in Rome at different times of the day, is the second of Respighi's trilogy of tone poems based on the city, along with "Fountains of Rome" (1917) and "Roman Festivals" (1928).
 It premiered on 14 December 1924 at the Augusteo Theatre in Rome with Bernardino Molinari conducting the Augusteo Orchestra.
A symphonic poem or tone poem is a piece of orchestral music, usually in a single continuous movement, which illustrates or evokes the content of a poem, short story, novel, painting, landscape, or other (non-musical) source.
 The German term "Tondichtung (tone poem)" appears to have been first used by the composer Carl Loewe in 1828.
 The Hungarian composer Franz Liszt first applied the term "Symphonische Dichtung" to his 13 works in this vein.
Ottorino Respighi (] ; 9 July 187918 April 1936) was an Italian violinist, composer and musicologist, best known for his three orchestral tone poems "Fountains of Rome" (1916), "Pines of Rome" (1924), and "Roman Festivals" (1928).
 His musicological interest in 16th-, 17th- and 18th-century music led him to compose pieces based on the music of these periods.
 He also wrote several operas, the most famous being "La fiamma".
Lucrezia is an opera in one act and three tableaux by Ottorino Respighi to a libretto by Claudio Guastalla, after Livy and William Shakespeare's "The Rape of Lucrece".
 Respighi died before finishing the work, which was therefore completed by the wife of the composer, Elsa Respighi, and by one of his pupils, Ennio Porrino.
 "Lucrezia" premiered on 24 February 1937 at the Teatro alla Scala in Milan, in a production directed by Mario Frigerio with sets designed by Pietro Aschieri.
 The première had a good reception.
Xin Huguang (16 October 1933 – 17 October 2011) was a modern Chinese composer.
 Born in Shanghai, her family came from Jiangxi in China's south.
 In 1948 she went to Nanchang, the capital of Jiangxi, to commence musical studies.
 In 1951 she enlisted at the Conservatory of the Central Music University in Beijing.
 Her classmate Mei Li Qi Ge introduced her to Mongolian folk music and this idiom informed her composing.
 She commenced collecting tapes and written articles on the subject.
 She met her future husband Bao Yu Shan, from Ke Zuo Zhong Qi in Mongolia while he was studying saxophone at the Conservatory.
 At the completion of her studies she composed Ga Da Mei Lin as a symphonic tone poem.
 The premier performance caused a stir as few could credit a 23-year-old female graduate with its composition.
 In that year she went with her husband to teach and compose music in Mongolia where she remained for the next 26 years.
 In 1982 she returned to Beijing to continue her work.
 In 1991 she visited America.
 She had three sons, the third of which, San Bao, was also a composer.
Elsa Respighi (née Olivieri-Sangiacomo) (24 March 1894 – 17 March 1996) was an Italian singer and composer.
 She was the wife and former pupil of Ottorino Respighi.
The Symphony No. 1 in D major by Gustav Mahler was mainly composed between late 1887 and March 1888, though it incorporates music Mahler had composed for previous works.
 It was composed while Mahler was second conductor at the Leipzig Opera, Germany.
 Although in his letters Mahler almost always referred to the work as a symphony, the first two performances described it as a symphonic poem or tone poem.
 The work was premièred at the Vigadó Concert Hall, Budapest, in 1889, but was not well received.
 Mahler made some major revisions for the second performance, given at Hamburg in October 1893; further alterations were made in the years prior to the first publication, in late 1898.
 Some modern performances and recordings give the work the title "Titan", despite the fact that Mahler only used this label for two early performances, and never after the work had reached its definitive four-movement form in 1896.
Danse macabre, Op.
 40, is a tone poem for orchestra, written in 1874 by the French composer Camille Saint-Saëns.
 It is in the key of G minor.
 It started out in 1872 as an art song for voice and piano with a French text by the poet Henri Cazalis, which is based on an old French superstition.
 In 1874, the composer expanded and reworked the piece into a tone poem, replacing the vocal line with a solo violin.
The Oceanides (Finnish title: Aallottaret , translated to English as "Nymphs of the Waves" or "Spirits of the Waves"; original working title "Rondeau der Wellen "; in English, "Rondo of the Waves"), Op.
 73, is a single-movement tone poem for orchestra written in 1913–14 by the Finnish composer Jean Sibelius.
 The piece, which refers to the nymphs in Greek mythology who inhabited the Mediterranean Sea, premiered on 4 June 1914 at the Norfolk Music Festival in Connecticut with Sibelius conducting.
 Praised upon its premiere as "the finest evocation of the sea ... ever ... produced in music", the tone poem, in D major, consists of two subjects, said to represent the playful activity of the nymphs and the majesty of the ocean, respectively.
 Sibelius gradually develops this material over three informal stages: first, a placid ocean; second, a gathering storm; and third, a thunderous wave-crash climax.
 As the tempest subsides, a final chord sounds, symbolizing the mighty power and limitless expanse of the sea.
The Wood Nymph (Swedish title: Skogsrået ; subtitled "ballade pour l'orchestre "), Op.
 15, is a programmatic tone poem for orchestra composed in 1894 and 1895 by the Finnish composer Jean Sibelius.
 The ballade, which premiered on 17 April 1895 in Helsinki, Finland, with Sibelius conducting, follows the Swedish writer Viktor Rydberg's 1882 poem of the same name, in which a young man, Björn, wanders into the forest and is seduced and driven to despair by a "skogsrå ", or wood nymph.
 Organizationally, the tone poem consists of four informal sections, each of which corresponds to one of the poem's four stanzas and evokes the mood of a particular episode: first, heroic vigor; second, frenetic activity; third, sensual love; and fourth, inconsolable grief.

Question: Which 1916 tone poem was composed by the husband of Elsa Respighi?
Answer: Fountains of Rome