Question
Earlier this year I planted Morning Glories and Moon Flowers along a fence in my driveway. There was nothing growing there previously... blank canvas, they grew fast and strong. Recently I have noticed that there is a vine amongst them that is similar but the buds are different. They have the same leaves... green anf heart-shaped, the stem however has more red in it and the buds are completely different. My morning Glories have already bloomed, these however have not. I am not sure whether or not my moon flowers have bloomed but I do have a few white ones that grow...look exactly the same as the Morning Glories (my Morning Glories that grow are a medium blue, don't remember the breed but I know it is not the heavenly blue, I think the second word begins with a p (I. p----) I tried to search online to find out if maybe it was a different type of these flowers. The buds are very dark maroonish and have three points toward the tips of them and then one point is growing in the middle. They are not growing as fast as the other plants and I didn't plant anything other than what I listed above. So I am not sure if maybe somehow there were different seeds that were mixed in. Please help me in finding out what these are... Oh and none of the seeds that I planted out of the package were any different than the rest... Thank you for your help in advance.

Answer
These Mystery Plant ID's are never easy, and it sometimes takes days to figure out what to say.  At this point, you are probably wondering if I've even read your question, so I should just post here what I can tell you and we'll see if we can expand on it.

Ipomoea purpurea, aka 'Common Morning Glory', may be the volunteer species you see.  To wit:

http://en.wikipedia.org/wiki/Ipomoea_purpurea

and

http://www.nearctica.com/flowers/bandc/convol/Ipurpur.htm

Ipomoea tricolor is the Morning Glory that gives us famous Heavenly Blue.  You state you are growing a different hybrid -- possibly I. tricolor 態lue Star?

http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/vines/ipomoea_tricolor.ht...

I. violacea抯 慞early Gates?bears stark White flowers:

http://www.botany.com/ipomoea.html

This may be the White vine you wrote about, separate from your Moonflower.

I. tricolor's 慡carlett O扝ara?(one of the original All-American selections) is a Rosy Fuchsia.  ALL of these are Ipomoea hybrids.  If they self-pollinate, the new plants will have dominant traits that you did not see in the present flowers.  Offspring from pollen of one Ipomoea/Morning Glory transferred to another do not necessarily look like either of parent.  Blue Star is classified in the line Ipomoea, subgenus Quamoclit, section Tricolor.  Ipomoeas often cross within their own series, but not between series (due to chromosome conflicts).  Remember, they don't have to be YOUR Ipomoeas they are crossing with -- a neighbor across the street or into the next county growing Morning Glories could supply one parent, another neighbor could supply the other, and the seeds just happen to end up near your Moonflowers and Morning Glories along the fence.

Botanist Yoshiaki Yoneda states that 'The varied Morning Glory was cross-bred by collecting the gene mutants that occurred in one biological species of Ipomoea nil and combining them.  Since then, it has been generally supposed that richer changes would be made by crossing the varied Morning Glory with closely related species. In particular, I. purpurea, the Common Morning Glory, has abundant variation because it has been bred for a long time in Europe and North America.?br>
Yoneda crossed I. nil with I. purpurea.  See his paper, 'Interspecific hybrid of the morning glory, Ipomoea nil', posted at his Morning Glories Encyclopedia website:

http://protist.i.hosei.ac.jp/Asagao/Yoneda_DB/E/species/hybrids.html

DNA analysis has found there are TWO basic kinds of Ipomoeas.

One group links sections Tricolores, Calonyction, and Pharbitis.

The other group includes sections Mina and Leptocallis.

As I understand it, the closer the two species, the higher the odds you will get good Seeds.  This is why we pay such close attention to these Sections and Groups classification labels.

Your fragrant, night-blooming 慚oonflower?(probably I. alba, possibly I. turbinata) often self-sows freely if left to seed.  Scientists did not know until recently the Moonflower was a species of the Morning Glory.  It is now classified in the line Ipomoea, subgenus Quamoclit, section Calonyction.  Being a White Ipomoea, it tends to self-pollinate more than colored Ipomoeas (red attracts Hummingbird pollinators, blue attracts bees, plus the Moonflower opens at dusk while the Morning Glory opens at dawn).

Bottom line: A self-pollinated Morning Glory hybrid is going to be the same species, but it won't have the best traits of the hybrid that produced it.  It takes years to get a new hybrid worth growing, with umpteen generations of similar plants that are the same species but varying colors, heights, shapes, etc.  This is not unusual.  But it is lots of fun to watch.