Here's the leaf blade description from Lesica (2012) for A) Lithophragma glabrum and B) Lithophragma parviflorum:
A) "glabrous below, sparsely hairy above, 5-20 mm wide, reniform, deeply 3-lobed and lobed again."
B) "white-hairy and glandular, 1-3 cm wide, suborbicular, twice deeply 3-lobed ."
Reniform means "kidney shaped" and suborbicular describes imperfectly circular. The leaf shapes don't sort the plants out by my eye using the photos below. On the other hand, leaf hairiness is distinct and quickly separates out the two species. The first key (Lesica 2012) in sorting these species is the number of lobes per flower petal; glabrum has five and parviflorum has three.
Reference: Manual of Montana Vascular Plants, Peter Lesica, 2012, Brit Press, Fort Worth, TX
Here's what they look like:
|Lithophragma glabrum flower|
|Lithophragma glabrum stem leaf|
|Lithophragma glabrum basal leaf|
|Lithophragma parviflorum flower|
|Lithophragma parviflorum stem leaf|
|Lithophragma parviflorum basal leaf|