Description from http://www.swcoloradowildflowers.com
"I. tenuituba tends to occur at relatively high elevations
or at least in subalpine fir and higher elevation sagebrush communities.
I. aggregata has a wide range of ecological associations
but generally is not at the upper limits of subalpine forest.
has a pale pink to lavender, sometimes very light purple corolla.
I. aggregata has a red to orange-red corolla.
has a more slender tube and is about 20-45 mm long.
I. aggregata has a tube about 15-25 mm long.
I. tenuituba has long, slender calyx lobes.
I. aggregata has shorter, tapering calyx lobes.
I. tenuituba has anthers within the tube, with no
more than one anther protruding from the throat.
I. aggregata has 3-5 anthers in the throat or protruding
beyond the throat.
I. tenuituba generally produces nectar in the early
morning or late afternoon, is sweet-smelling in the evening, and is pollinated
principally by moths, sometimes butterflies.
I. aggregata generally produces nectar during the
day in large quantities, is odorless, and is pollinated principally by hummingbirds.
The two species do hybridize." Al Schneider who received
the information from Dieter Wilken of the Santa Barbara Botanic Garden