Morning glories (Convolvulus) are indispensable.  There is nothing better for covering trellises, arches or tuteurs and, as long as you have some kind of tall, relatively sturdy support, you can even grow them in pots.  They are also perfect for people who don't want to commit to a perennial vine like clematis. 

Most years I start my morning glories from fresh seed that I buy each spring.  This past spring I used seed that I had collected from the previous year's plants.  The results were interesting.  Though last summer's beds held a mix of varieties, the only one that has sprouted reliably from the collected seed is the heirloom variety 'Grandpa Ott's'.  I am not sure what happened to all the others, but 'Grandpa Ott's' has come through valiantly, producing more dark purple blooms every day. 

It's possible that some of the others are simply late bloomers.  The spring was dry and all the plants got off to a slow start.  I check every day in the hopes of finding a few blue or pink blossoms.  I do enjoy mixed colors, so next spring, I'll probably buy fresh seed.  For now, though, I'll be content watching 'Grandpa' work his way up to the second storey of my house.