Herbaceous species and hybrids of Kniphofia have narrow, grass-like leaves 10–100 cm (4–39 in) long, while evergreen species have broader, strap-shaped foliage up to 1.5 m (5 ft) long. All plants produce spikes of upright, brightly coloured flowers well above the foliage, in shades of red, orange and yellow, often bicoloured. The flowers produce copious nectar while blooming and are attractive to bees and sunbirds. In the New World they may attract sap-suckers such as hummingbirds and New World orioles. The genus Kniphofia is named after Johann Hieronymus Kniphof, an 18th-century German physician and botanist. Several species of Kniphofia are cultivated as garden plants, valued for their architectural properties. These include K. galpini, K. northiae, K. rooperi and K. thomsonii.