One aspect of "simplicity" in the main theme is the blocking of the chordal accompaniment, which adds a sort of untutored—I am tempted to say "Grandma Moses"—quality to the whole. The system below the theme score reduces the voiceleading to its textbook or classroom version, and there one can see more easily the V9 harmonies. An interesting point about bar 4: a plausible and rare second inversion of the dominant ninth chord (I write about inversions of the "extended" chords in the Gallery essay). In the cadence, we are obliged to imagine the E4 to which the ninth F#4 would resolve, but it's a very easy one in this context.
The design of "To a Wild Rose" is a simple ternary form; the relatively brief B-section is shown below.
Here again a voiceleading reduction is useful, including the addition of an obvious implied dominant pedal point (one is grateful to MacDowell's artistic sense not to ask for this literally).
In the ending, both V9/V and the cadential V9 are no longer present. Instead, we have the more traditional viiø7/V (understood by theorists of the time as the V9 without its root—a bizarre idea if we think about it now, but it made sense at the time, as everyone was attempting to adjust the system of figured bass to the new Ramellian (that's Rameau's) scheme of fundamental bass and three functions, tonic, dominant, and subdominant). Here, MacDowell makes out of the circled chord a wonderfully expressive highpoint, pianissimo.
