Asa Gray (November 18, 1810 - January 30, 1888) is considered the most important American botanist of the 19th century. His Darwiniana was considered an important explanation of how religion and science were not necessarily mutually exclusive. Gray was adamant that a genetic connection must exist between all members of a species. He was also strongly opposed to the ideas of hybridization within one generation and special creation in the sense of its not allowing for evolution, as he felt evolution was guided by a Creator.

Prior to 1840, besides what he had discovered during his trip to Europe, Gray's knowledge of the flora of the American West was limited to what he could learn from Edwin James, who had been on the expedition to the West of Major Stephen Harriman Long, and from Thomas Nuttall, who had been on an expedition to the Pacific coast with Nathaniel Jarvis Wyeth. In the latter half of 1840, Gray met the German-American botanist and physician George Engelmann in New York City. Engelmann took frequent trips to explore the American West and northern Mexico. The two remained close friends and botanical collaborators. Engelmann would send specimens to Gray, who would classify them and act as a sales agent. Their collaborations greatly enhanced botanical knowledge of those areas. Another German-American botanist, Ferdinand Lindheimer, collaborated with both Engelmann and Gray, focusing on collecting plants in Texas, hoping to find specimens with "no Latin names". Another long-term and productive collaboration was with Charles Wright, who collected in Texas and New Mexico on two separate expeditions in 1849 and 1851-1852. These trips resulted in publication of the two-volume Plantae Wrightianae in 1852-1853.  Gray traveled to the American West on two separate occasions, the first in 1872 by train, and then again with Joseph Dalton Hooker, son of William Hooker, in 1877. His wife accompanied him on both trips. Both times his goal was botanical research, and he avidly collected plant specimens to bring back with him to Harvard. On his second trip through the American West, he and Hooker reportedly collected over 1,000 specimens. Gray's and Hooker's research was reported in their joint 1880 publication, "The Vegetation of the Rocky Mountain Region and a Comparison with that of Other Parts of the World," which appeared in volume six of Hayden's Bulletin of the United States Geological and Geophysical Survey of the Territories.  On both trips he climbed Grays Peak, one of Colorado's many fourteeners. His wife climbed Grays Peak with him in 1872. This mountain was named after Gray by the botanist and explorer of the Rocky Mountains Charles Christopher Parry.  Prior to the 1870s, collecting in the western part of the country required slow horses, wagons, and often military escorts. But by this time, permanent settlements and railroads resulted in so many specimens coming in that Gray alone could not keep up with them. One of the post-war collectors who worked extensively with Gray was John Gill Lemmon, husband of fellow botanist Sara Plummer Lemmon. Gray named a new genus Plummera, now called Hymenoxys, in Sara's honor.

Using a quote from the above article, answer the following question: Did Gray and Hooker work on any other projects?