Grant, V. and D. Wilken. 1986. Taxonomy of the Ipomopsis aggregata group (Polemoniaceae). Botanical Gazette 147: 359-371.

Wilken, D. and S. Allard. 1986. Intergradation among populations of the Ipomopsis aggregata complex in the Colorado Front Range. Systematic Botany 11: 1-13.

Freeman, E. and D. Wilken. 1987. Variation in nectar-sugar composition at the intra-plant level in Ipomopsis longiflora (Polemoniaceae). American Journal of Botany 74: 1681- 1689.

Grant, V. and D. Wilken. 1987. Secondary intergradation between Ipomopsis aggregata ssp. candida and I. a. collina (Polemoniaceae). Botanical Gazette 148: 372-378.

Henrickson, J. 1987. New species, combinations, and notes in Ipomopsis (Polemoniaceae). Aliso 11: 589–598.

Grant, V. and D. Wilken. 1988. Natural hybridization between Ipomopsis aggregata and I. tenuituba (Polemoniaceae). Botanical Gazette 149: 213-221.

Grant, V. and D. Wilken. 1988. Racial variation in Ipomopsis tenuituba (Polemoniaceae). Botanical Gazette 149: 443-449.

Wilken, D. and R. Fletcher. 1988. Ipomopsis sancti-spiritus (Polemoniaceae), a new species from northern New Mexico. Brittonia 40: 48-51.

Wilken, D. and R. Hartman. 1991. A revision of the Ipomopsis spicata complex (Polemoniaceae). Systematic Botany 16: 143-161.

Wilken, D. 1996. Demography of Ipomopsis aggregata ssp. weberi, a rare plant of northern Colorado. pp. 13-18. In Maschinski et al. (eds.) Proceedings, Second Southwestern Rare and Endangered Plants Conference. USDA, Forest Service, Flagstaff, AZ