Narrow-leaf Collomia is a simple, single-stemmed annual to 60 cm tall. Occasionally larger plants may have several to many side branches of the main stem. The leaves are numerous, sessile, entire, and lanceolate or linear in shape. Individual leaves range in length from 1 to 7 cm long and 1 to 13 mm wide. The broadest leaves are those under the flower clusters.
Each branch of the stem ends in dense, leafy-bracteate cluster of sessile flowers. Those below are smaller than the uppermost inflorescence. The corolla is usually pink, blue, or white. The thin tube is about 8 to 15 mm long with the corolla lobes short at 1.5 to 3 mm long.
Narrow-leaf Collomia is found from the lowlands to moderate elevations in the mountains. It is a plant of dry to moderately moist, open or lightly shade ground.
A wide ranging plant, Narrow-leaf Collomia is found from British Columbia eastward to Ontario and Quebec, and southward to California, Nebraska, and New Mexico. In the Pacific Northwest, it is found wholly east of the Cascade crest.
