Coneflowers will do okay in that kind of sun either front or back. They grow pretty fast.

If you're looking for host plants, an aristolochia like tomentosa, will do fine in either location as well (host for Pipevine Swallowtails).

My cassias do well with the approx 7-2pm sun. Fennel will also (host for Black Swallowtails).

Rue should do nicely, too (host for Black and Giant Swallowtails).

Just about anything that requires full sun will do okay in the 7-2 p.m. sun. It's the west sun that's difficult to find things for IMHO.

Salvias will do okay in the 7-2 area, and perhaps in the 2-7 as well (may not bloom "as" prolifically). The pink and white Texas Sage for sure.

Veronicas (speedwell)
Milkweeds (incarnata and cultivars; purpurescens; curassavica)

MissSherry probably has a whole list for you since is from Louisiana too.

Susan

I know this will sound really stupid, but what is a host plant?

No such thing as a stupid question. A host plant is a plant a butterfly uses to lay eggs on. Every species of butterfly has a certain specific host plant.

As Miss Sherry mentions above, Black swallowtails lay eggs on fennel. Monarchs lay eggs on asclepias, common name milkweed.

Edna ;-)

I've linked a great website below that has great information on nectar and host plants for butterflies and moths across North America. I use it as a reference guide all the time.

Here is a link that might be useful: Butterflies and Moths of North America

Here's my article about partial - shade plants.

Butterfly Partial-Shade Gardening
In general butterflies and shade don't go together, but there are a few exceptions. I have some garden spots which only get 3 hours of sun each day. Normally this isn't enough for most plants, but some will grow and thrive under these conditions. Here's a list of possible shade plants and my experience with them.
Asters - many types
They may not get quite a large as their sunny cousins, but are ok.

Bidens alba
A prolific grower. This is an annual.

Dianthus
Some varieties do pretty well in the shade.

Dill and Parsley
Both seem to do fine.

Dogwood
Actually does better in partial shade than full sun.

Globe Amaranth.
They give a lot of color to the garden as well as nectar for the butterflies.

Goldenrod
Does well.

Heliopsis
Does great, but has a tendency to get tall. Trim it down to size.

Hop Tree
This is not only the host plant for the Giant Swallowtail, but does well under other trees. Doesn't get large.

Impatiens
Can be a nectar source for some butterflies.

Marigolds
My smaller marigolds do great with very little sun and are a fair nectar source for some butterflies.

Moonbeam Coreopsis
Low growing with lots of small yellow flowers. It's a good nectar source for the smaller butterflies. Deadhead the flowers for continuous blooms.

Purple Coneflower
Grows in almost any conditions.

Rudbeckia
Most types seem to do well.

Salvia - Lady in Red
A prolific grower in almost any conditions.
Shasta Daisy - Becky
Seems to do ok in partial shade.

Tropical Milkweed.
It's a host plant and a preferred nectar source for traveling Monarchs and other butterflies.

Violets
Do ok.

Ok, so I am about to go shopping online (Theres this site that gives money [Practically] free, and I can order anything I want). So, online shopping here I come, I have $20. I am looking for these plants as seeds(since they are cheaper duh), but I am seeing different kinds of them. Like Rue, theres about 5 million different kinds. Could one of you point me into the right direction, or help me shop. It would be very helpful :]