Checklist of the Vascular Plants of Texas
The Checklist of the Vascular Plants of Texasdivides Texas into ten vegetation regions and provides a summary of soil types and typical plants found in each area. You can search the checklist by common or botanical name and find a brief description of the plant. Unfortunately, no photos or illustrations of plants are provided, and if you don't know the name, there is no alternative method of searching. Even so, the site is useful for determining which plants grow in which area of Texas.
Desert Butterfly Gardening
Desert Butterfly Gardening (Arizona Native Plant Society and the Sonoran Arthropod Studies Institute, 1996; $2) is a slim pamphlet that packs a wealth of information on plants that attract specific butterfly families. There is a helpful description of their lifecycle from egg to larva to pupa to adult, hints on designing a butterfly garden, and color photos of the flowers and the butterflies they attract.