Alyssum was originally white and it was hybridized to be colored. All hybrid plants may not come true to form when they reseed and may revert back to the original form.

So too do many dark colored plants bleach in a hot sun

Alyssun really is not for hot places it prefers a place where it gets a little shade in the day. If she wants color and something that can stand the heat plant marigolds. You can get marigolds that are only 6 to 10 inches high. You can also alternate one alyssum and one marigold or some other heat and sun loving plant so the other plant shades the alyssum.

How about Portulaca? One of my favorites for color and they will tolerate the heat there.

I've always considered alyssum a cool season plant. In a sunny zone 9, it might bloom all winter...fading only when it gets hot. (It is in the Brassicaceae family, along with cabbage, collards, broccoli, etc.)

I sure agree with Portulaca! Lantana would be a good choice, too, though it's becoming sooo overused.

If she likes yellow, how about perennial alyssum, "Basket of Gold"?

Here is a link that might be useful: Basket of Gold

Alyssum poops out on me when it gets too hot, and I'm in zone 5b/6, can't imagine it would last very long in your zone at all.

You'd be better off with some heat/sun lovers. Vinca would be a great choice as long as the soil isn't too wet - vinca thrives in heat and sun. Lots of beatiful colors from which to choose, too.

I wonder if your mom would like some of the verbenas? They come in colors in the blue/pink range, but include some brilliant purples, fuchsias and reds. They love heat and bloom all summer, despite being perennials, especially in your zone.

Alyssum poops out on me when it gets too hot, and I'm in zone 5b/6, can't imagine it would last very long in your zone at all.

That surprises me, Mxk3. My folks, in TC, have always had it planted around their birdbath in the middle of their yard. It gets full sun from 9-4 and they've never had a problem with it 'pooping out'. Some years it actually has been too successful and has tried to muscle out smaller plants.

Is your mom also in zone 9? I grow alyssum here as a winter annual. The only time it survived the summer was the year I planted it in mostly shade. It looked straggly all summer, then came back larger and more beautiful the following fall/winter. I have never been able to get the purple ones to look good at any time of the year.

One of my favorite summer plants with a similar look and growth habit is Dahlberg Daisy. It is a bright, sunny yellow, and will thrive along a driveway. Above suggestions of Portulaca and Periwinkle (Vinca) would also do well.

Here is a link that might be useful: Dahlberg Daisy

LOL! My bad, NT! I neglected to look at your zone.