Identification: This perennial plant can grow in sunny high altitude (5,000-10,000 ft) areas of Maui County. Young plants consist of a short rosette of blue-gray felt-like leaves 10-30 cm (4-12 in) long and 2-12 cm (1-5 in) wide with a rounded tip. Leaves become smaller as the plant grows taller, eventually reaching 3 m (10 ft) tall by the second year. Conspicuous flower stalk with yellow flowers. The large felty leaves are very distinctive.
Impacts: Common mullein can become invasive by quickly colonizing disturbed areas. It produces numerous seeds that may remain dormant in the soil for over 100 years. On the island of Hawaii mullein infests roadsides at elevations from 5,000-10,000 ft and is particularly dense around 6,562 ft (2,000 m) forming a dense stands that can out-compete native vegetation.
Dispersal Mechanism: Common mullein is dispersed over long distances in the horticulture trade, and by birds who love to eat the seed. In Hawai‘i, it has been speculated that seeds are dispersed in mud along roads by cars and along trails by hikers. Common mullein has only been known to grow in a few locations in Maui County (upcountry East Maui; see map). All known locations of this pest have been removed from the island by the Maui Invasive Species Committee.

More information about this pest 

Common mullein look-alikes:

Telegraph weed (Heterotheca grandiflora):
Telegraph weed grows in sunny, high altitude areas of Maui County. Plants form a rosette of hairy leaves which may be confused with common mullien. Telegraph weed's leaves have pointed tips and a strong, sagey smell when crushed.

Primrose (Oenothera spp.):
Primrose grows in sunny, high altitude areas of Maui County. Plants form a rosette of slightly hairy leaves which may be confused with common mullien. Primroses have lance-like leaves with pointed tips versus the rounded tip of the common mullien and produce large, showy flowers up to 5 cm (2 in) across.