Question: Who was contracted to design golden gate park?

Disambiguated questions and answers:
context: In the 1860s, San Franciscans began to feel the need for a spacious public park similar to Central Park, which was then taking shape in New York City. Golden Gate Park was carved out of unpromising sand and shore dunes that were known as the Outside Lands, in an unincorporated area west of San Francisco's then-current borders. Conceived ostensibly for recreation, the underlying purpose of the park was housing development and the westward expansion of the city. The tireless field engineer William Hammond Hall prepared a survey and topographic map of the park site in 1870 and became its commissioner in 1871. He was later named California's first state engineer and developed an integrated flood control system for the Sacramento Valley. The park drew its name from nearby Golden Gate Strait.
question: Who was contracted as commissioner to design golden gate park?
short_answers: William Hammond Hall
wikipage: Golden Gate Park

context: The plan and planting were developed by Hall and his assistant, John McLaren, who had apprenticed in Scotland, home of many of the 19th-century's best professional gardeners. John McLaren, when asked by the Park Commission if he could make Golden Gate Park "one of the beauty spots of the world," replied saying, "With your aid gentleman, and God be willing, that I shall do." He also promised that he'd "go out into the country and walk along a stream until he found a farm, and that he'd come back to the garden and recreate what nature had done." The initial plan called for grade separations of transverse roadways through the park, as Frederick Law Olmsted had provided for Central Park, but budget constraints and the positioning of the Arboretum and the Concourse ended the plan. In 1876, the plan was almost replaced by one for a racetrack, favored by "the Big Four" millionaires: Leland Stanford, Mark Hopkins, Collis P. Huntington, and Charles Crocker. Stanford, who was president of the Southern Pacific Railroad, was also one of the owners of the Ocean Railroad Company, which ran from Haight Street across the park to its south border, then out to the beach and north to a point near Cliff House. It was Gus Mooney who claimed land adjacent to the park on Ocean Beach. Many of Mooney's friends also staked claims and built shanties on the beach to sell refreshments to the patrons of the park. Hall resigned, and the remaining park commissioners followed. In 1882 Governor George C. Perkins appointed Frank M. Pixley, founder and editor of The Argonaut, to the board of commissioners of San Francisco's Golden Gate Park. Pixley was adamant that the Mooney's shanties be eliminated, and he found support with the San Francisco Police for park security. Pixley favored Stanford's company by granting a fifty-year lease on the route that closed the park on three sides to competition. The original plan, however, was back on track by 1886, when streetcars delivered over 47,000 people to Golden Gate Park on one weekend afternoon (out of a population of 250,000 in the city).
question: Who was contracted to design golden gate park as Hall's assistant and successfully introduced new plant species?
short_answers: John McLaren

Dr John Hays McLaren
wikipage: Golden Gate Park

Long answers:
knowledge: content: is credited with planting two million trees during his lifetime.
wikipage: John McLaren (horticulturist)

content: Dr John Hays McLaren (1846–1943) served as superintendent of the Golden Gate Park in San Francisco, CA for 56 years.
wikipage: John McLaren (horticulturist)
long_answer: William Hammond Hall along with his assistant, John McLaren, designed Golden Gate Park in San Francisco. John McLaren would go on to serve as superintendent of Golden Gate Park for 56 years and is credited with planting more than two million trees during his lifetime. William Hammond Hall would later be named California's first state engineer.