Penstemon hallii
Scrophulariaceae (Snapdragon Family)

Elihu Hall, 1820-1882, was a farmer, sometimes botanist, and one of organizers of the Illinois Natural History Society.  He and Jared Patterson Harbour apparently contracted with famed Charles Christopher Parry to lead them, accompany them, and/or collect with them in the Idaho Springs, Colorado area. 

It was common for multiple sets of plants to be collected and then sold to pay for expenses and finance more collecting trips. The Hall-Harbour-Parry summer trip of 1862 seems to have had finances as a key motivating factor: Hall, for instance, wanted money for a new house and was willing to sell sets of plants quickly and cheaply after the trip (according to Ewan in his Biographical Dictionary...).  Weber indicates that the collecting expedition gathered ten sets of over 700 species and that this remains "the largest [collection] [ever] made in Colorado in a single season". 

Whatever the motivation and details, the collection was described by Gray and Torrey and Asa Gray considered it "full, excellent, and of great interest".