Rhizomes sheathed with old leaf bases, slender, 0.6-0.9 cm diam.; roots few, fibrous. Stems simple, solid, 1.5-3 dm. Leaves: basal with abaxial surface of blades deep glossy green on one side of fan, light yellow-green on other side, pink or red-tinged basally, strongly ribbed, 4-6 dm × 0.8-1 cm, rigid, margins not thickened; cauline 3-6, imbricated, closely sheathing stem ca. 2/3 length, spreading distally, bractlike, blade inflated, often shorter than basal leaves. Inflorescences simple, units 1-2-flowered; spathes closed tightly around pedicel and ovary, lanceolate, 5.2-9 cm × 6-8 mm, subequal, herbaceous, margins scarious, apex acuminate. Flowers: perianth cream to buff-yellow; floral tube 0.8-0.9 cm; sepals with deeper yellow signal, veined with purple or brown, obovate-lanceolate, 6.5 × 2.5 cm, base gradually attenuate into wide claw; petals narrowly oblanceolate, 7-9 × 0.8-2 cm, base gradually attenuate; ovary nearly circular in cross section, 1.5-2.5 cm, base gradually attenuate into pedicel, apex abruptly acuminate into floral tube; style 2.2-3 cm, crests spreading, yellow, not veined, 1.2 × 0.9-1.7 cm, margins toothed; stigmas triangular or tongue-shaped, margins entire; pedicel 3-6.2 cm. Capsules nearly circular in cross section, tapering abruptly at each end, 2-2.5 × 1-1.5 cm. Seeds dark brown, irregular in shape, wrinkled. 2n = 40.
Iris bracteata is limited to one county each in northern California and southern Oregon. It hybridizes with I. chrysophylla, I. douglasiana, I. innominata, I. munzii, I. purdyi, and I. tenax.