I'm looking for information on Clarence Howard Clark, 1833 – 1906 who was a president of PHS.
Thank you so much for contacting the Pennsylvania Horticultural Society concerning early member Clarence H. Clark who served as president of the Society from 1895 to 1898. You may be interested in the references to Mr. Clark in James Boyd’s History of the Pennsylvania Horticultural Society 1827-1927 (1929). The book is online and you need only to copy and paste the url below for references to Clark indicated by the orange pins at the bottom of the screen (depending on your internet connection, it might take some time to load). Boyd constructed the history chiefly from the Society’s minutes for Clark’s participation in meetings, exhibitions, and a record of his presidency (there is also a short biographical sketch on page 386).
You probably also saw the wikipedia entry on C. H. Clark.
Please let me know if you need any other information.