Septentrionalis Characteristics
   - annuals
   - flowers in diffuse umbel, with pedicels over 5 mm long
   - bracts below inflorescence lanceolate to awl-shaped
   - flowers small
   - corolla about the same length as the calyx
 
Androsace Characteristics
   - Budd's Flora keys genus Androsace as having "flowers small 
     and white", and then keys Androsace chamaejasme as having 
     "flowers large"

   - annuals
   - leaves in a basal rosette (plus leafy bracts below umbels)
   - flowers in umbels
   - flowers white
   - sepals and petals not reflexed 
   - corolla tube mostly shorter than calyx, its throat 
     constricted
   - stamens separate 
   - style minute

Primulaceae Characteristics (except for Glaux which have no 
                             corolla)
   - plants not twining
   - plants without milky juice
   - flowers not in heads or spikes
   - petals and sepals both present (except for Glaux)
   - corolla regular
   - petals partially united to form a tube
   - same number of stamens as corolla lobes
   - stamens directly in front of (not alternating with) corolla 
     lobes
   - ovary superior