Line 1: “Morning glory” – F. Pursh Flora Amer. Septentrionalis I. 146 Ipomoea Nil.‥ Flowers beautiful pale blue, only open early in the morning, from which it has been called Morning-glory (OED).
Morning glory flower, species Ipomoea nil. Courtesy of Wikimedia Commons.
Line 2: “Lintel”- A horizontal piece of timber, stone, etc. placed over a door, window, or other opening to discharge the superincumbent weight (OED). The top of the doorway or threshold.
Line 5: “Bison thunder” – A stampede of bison; a common fixture of prairie life.
"Tatanka Bison" (2001). Courtesy of Wikimedia Commons.
Line 10: “Gold trail” – Referring to the trail that lead to the gold rush, specified in the text as being to Colorado in this instance, probably followed in 1859 (Indiana, Line 26)
"Prospectors in what was then the "Pikes Peak" region". Courtesy of Wikimedia Commons.
Line 11: “Drop the scythe to grasp the oar” He leaves his home farm life for an idealistically adventurous career at sea, the scythe being agriculture and the oar being nautical.
Line 13: “Prodigal” – Of a person: that has lived a reckless or extravagant life away from home, but subsequently made a repentant return. Also more generally and fig.: that has gone astray; errant, wayward; wandering. Freq. in prodigal son (also daughter, child) , with allusion to Luke 15:11–32. (OED)
Line 14: “Seminary Hill” – No obvious reference to a physical place or location, however, seminary literally means: A place of origin and early development; a place or thing in which something (e.g. an art or science, a virtue or vice) is developed or cultivated, or from which it is propagated abundantly. (OED)
Line 15: “God lavish there in Colorado” – Colorado was a gold mining hotspot in the 1850s; the promise of profit would have been well known, tempting, but inevitably too good to be true for most.
Down in Colorado gold mine: taking out ore, Eagle River Canyon, Colorado, U.S.A. Courtesy of NYPL Digital Gallery.
Line 17: “Firecat” – No OED or Encyclopedia reference, perhaps a midwestern colloquial term. It does appear in the opening poem Earthy Anecdote in Wallace Steven’s Harmonium.
Line 18: “sluggard freshets” – freshets – A stream of fresh water flowing into the sea or a flood or overflowing of a river caused by heavy rains or melted snow (OED). Most likely the former, as the speaker is panning for gold. Use of “sluggard”, sluggish, slothful, or lazy (OED), indicates the slow process of panning as well.
Line 20: “His gleaming name” – The gleaming refers to the gold pieces found, God’s name in fortune in the form of gold pieces.
Line 21: “Eldorado” – The name of a fictitious country (according to some a city) abounding in gold, believed by the Spanish and by Sir Walter Raleigh to exist upon the Amazon within the jurisdiction of the governor of Guiana (now Guyana) (OED).