Penstemon digitalis which repeat with two flowers multiple times. The pedicels are almost one fourth of an inch long and produce 1.25 inch long two-lipped tubular flowers over dark green foliage. The plant has elliptic basal leaves and lance-shaped to oblong stem leaves. It is called beardtongue because the plant has a fifth stamen which resembles a hairy beard due to having small hairs. "Penstemon" is a combination of the Greek words, "penta", "five" and "stemon", referring to the stamen, every flower containing five stamens. Four of the stamens are fertile while the fifth one is sterile. The Latin word "digitalis" means
Derive (computer algebra system) 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 pocket