Newspaper accounts called Brown not only a great jurist, but also a great scientist, learned as a botanist and to a lesser degree as an astronomer.
Obituaries noted his versatility and compared him to polymath poet and doctor Oliver Wendell Holmes Sr.
Modern sources have also recognized his wide range of pursuits and accomplishments.

In 1875, Brown joined the  Torrey Botanical Club of  Columbia College in New York and was an active member for many years, serving as president from 1893 to 1905.
As the club's president, Brown served on the Botanical Garden Committee and became a principal founder of the New York Botanical Garden.
Brown cited his role in the Botanical Garden's founding as his most significant public service, aside from his work in the judiciary.
He wrote that organization's charter in 1891 and in that year donated the initial $25,000 (which he viewed as "quite out of proportion to my means at that time") toward the $250,000 in private seed money required pursuant to the New York legislature's authorization for municipal contributions.

Brown traveled to collect botanical specimens, maintained an extensive botanical library, wrote many notes for Torrey Botanical Club publications and published the following works:  
Illustrated Flora of the Northern United States and Canada (three volumes, 1896–98; new edition, 1913 — with Nathaniel L. Britton)
The Elgin Botanical Garden and its Relation to Columbia College and the New Hampshire Grants (1908)
At age 81, Brown began work on a revised and expanded edition of Illustrated Flora, which contained over 2,000 pages and some 5,000 illustrations.
With his co-author Britton, he worked on this for the rest of his life, even as his health failed.
Brown died four days after the first bound copies were shipped.

At his death, Brown's single largest charitable bequest—200 shares of  United States Steel preferred stock worth $21,750 in 1913—was to the New York Botanical Garden to endow a botanical journal.
The periodical was to be named for Brown and to contain color plates illustrating plants of the United States and its territories.
This publication, named Addisonia, was issued between 1916 and 1964.

Brown was also a serious amateur astronomer.
He was a founding member of the New York Academy of Science's astronomy section.
Brown's Colorado mountaintop observations of the July 29, 1878 solar eclipse were included in a report of the United States Naval Observatory.
Newspaper accounts called Brown not only a great jurist, but also a great scientist, learned as a botanist and to a lesser degree as an astronomer. Obituaries noted his versatility and compared him to polymath poet and doctor Oliver Wendell Holmes Sr. Modern sources have also recognized his wide range of pursuits and accomplishments.
In 1875, Brown joined the  Torrey Botanical Club of  Columbia College in New York and was an active member for many years, serving as president from 1893 to 1905. As the club's president, Brown served on the Botanical Garden Committee and became a principal founder of the New York Botanical Garden. Brown cited his role in the Botanical Garden's founding as his most significant public service, aside from his work in the judiciary. He wrote that organization's charter in 1891 and in that year donated the initial $25,000 (which he viewed as "quite out of proportion to my means at that time") toward the $250,000 in private seed money required pursuant to the New York legislature's authorization for municipal contributions. 
Brown traveled to collect botanical specimens, maintained an extensive botanical library, wrote many notes for Torrey Botanical Club publications and published the following works:  
Illustrated Flora of the Northern United States and Canada (three volumes, 1896–98; new edition, 1913 — with Nathaniel L. Britton)
The Elgin Botanical Garden and its Relation to Columbia College and the New Hampshire Grants (1908)
At age 81, Brown began work on a revised and expanded edition of Illustrated Flora, which contained over 2,000 pages and some 5,000 illustrations. With his co-author Britton, he worked on this for the rest of his life, even as his health failed. Brown died four days after the first bound copies were shipped.
At his death, Brown's single largest charitable bequest—200 shares of  United States Steel preferred stock worth $21,750 in 1913—was to the New York Botanical Garden to endow a botanical journal. The periodical was to be named for Brown and to contain color plates illustrating plants of the United States and its territories. This publication, named Addisonia, was issued between 1916 and 1964.
Brown was also a serious amateur astronomer. He was a founding member of the New York Academy of Science's astronomy section. Brown's Colorado mountaintop observations of the July 29, 1878 solar eclipse were included in a report of the United States Naval Observatory.
Addison Brown