Clematis rhymes with:
altice, anstice, anstiss, artis, arvanitis, aseritis, atlantis, atlantis', battis, bettis, botrytis, burtis, courtis, curtice, curtis', curtiss, custis, debenedictis, delaurentis, derobertis, desanctis, desantis, devincentis, disantis, duplantis, estis, eustice, fortis, fotis, fratus, gattis, gettis, gottis, hartis, huestis, injustice, intis, justis, kariotis, kasputys, kurtis, lamastus, lantis, lettice, loftis, logothetis, maldutis, maniatis, mantis, martis, matis, mattice, mattis, matus, mazaitis, mertice, metis, moraitis, mortis, myrtice, myrtis, notis, oatis, ortis, otis, pattis, peratis, peratis', petraitis, pettis, phlebitis, pneumocystis, politis, portis, prentice, prentiss, sholtis, shultis, solstice, soltis, veliotis, whitis, yantis
Clematis sounds like:
calamities, calamitous, calmat's, claimants, claimants', clemente's, clementes, clements, clementz, client's, clients, clients', climates, climatic, clonts, clontz, coolants, culminates