Well, you may need to look for them at different times of the
year. I not a hundred % sure of this, but I think D.brev goes
dormant similar to D.cistiflora in that all that's left is some
fleshy roots over the dormancy. Large plants are about 1 cm
across while the roots are as think as those of D.filiformis,
which is tens of times larger! They probably go dormant when
ever it gets too dry for them. So mid-summer would be the worse
time to look for them, although I've been able to find them
in spring and summer in wet places growing with D.capillaris.
We even found some Unidentified Drosera seedlings (either D.cap,
intermedia or brev; or all three) growing on one of those food
and fuel islands along an interstate in FL where it couldn't be
very wet all the time so I doubt D.intermedia.
Dave Evans