Penstemon digitalis the plant that is named Dark Towers. The hybrid has tubular pink flowers that grow up to 1.5 inches tall, red foliage, and is 1.5 feet to 3 feet tall. Although Dark Towers is similar to Husker Red, its red foliage is darker than that of the Husker Red cultivar and has more height. It also stays red for a longer time in the summer. Dale Lindgren created and named both Husker Red and Dark Towers at the University of Nebraska in 1983. Lindgren decided to create Husker Red because of its purplish-red foliage. Penstemon digitalis Penstemon digitalis (foxglove beard-tongue,
Derive (computer algebra system) calculators. Derive (computer algebra system) Derive was a computer algebra system, developed as a successor to muMATH by the Soft Warehouse in Honolulu, Hawaii, now owned by Texas Instruments. Derive was implemented in , also by Soft Warehouse. The first release was in 1988 for DOS. It was discontinued on June 29, 2007 in favor of the TI-Nspire CAS. The last and final version is Derive 6.1 for Windows. Since Derive required comparably little memory, it was suitable for use on older and smaller machines. It was available for the DOS and Windows platforms and was used also in TI