Annual, with erect, wiry, sparsely branched stem, 10-150 mm tall. Leaves sessile, obovate to linear, dorsiventrally flattened and slightly fleshy, 5-12 x 1-6 mm. Flowers usually in a loose, terminal cluster, funnel-shaped, petals 8-12 mm long, yellow to orange, often darker in tube.
Annual with wiry stems to 20 cm. Leaves opposite, subterete to obovate. Flowers in a terminal thyrse, cup-shaped, yellow to orange, often marked red in throat, petals 8-15 mm long, stigmas terminal on slender styles.