Seed Production With Insect Herbivory and Fungal Occurrence for the Rare \u3ci\u3ePenstemon haydenii\u3c/i\u3e

We quantified seed production and viability, floral herbivory and fungal infection on blowout penstemon (Penstemon haydenii S. Watson), an endangered species of the Nebraska Sandhills, USA, in order to determine the potential for perpetuation of this, and possibly other short-lived, rare perennials of fragmented habitats. Over three years, the number of seeds per infructescence averaged 518 (SE 29.01). Plants produced an average of 1398 seeds. Seed viability of 38% reduced reproductive potential to 531 viable seeds per plant. Plants in multiple blowout sites in two counties were assigned to one of four treatments: insecticide, fungicide, both, or neither (control). Insect herbivore damage varied between site-year combinations, but was not successfully reduced by treatments. For example, grasshoppers (Orthoptera, Suborder Caelifera) caused high levels of herbivory at the Hooker County sites in 2007. All three non-control treatments reduced visible signs of fungal occurrence, except in Hooker County in 2006. However, total seed number per plant, seed weight, and seed viability were similar among treatments, suggesting fungal attack did not reduce fecundity. The main difference observed was significant variation in each of these parameters of plant performance among site-year combinations. Consequently, we conclude that site-specific conditions are important to blowout penstemon regeneration