- Kingdom Plantae – Plants
- Subkingdom Tracheobionta – Vascular plants
- Superdivision Spermatophyta – Seed plants
- Division Magnoliophyta – Flowering plants
- Class Magnoliopsida – Dicotyledons
- Subclass Rosidae
- Order Myrtales
- Family Onagraceae - Evening Primrose family
- Genus Achillea L. – yarrow
- Species Achillea millefolium L. – common yarrow
General: Annual, the stem 1-10 dm. tall, simple or freely-branched. Leaves: Leaves alternate, sessile, 2-7 cm. long and 2-6 mm. wide. Flowers: Inflorescence of loose, few-flowered, erect racemes; calyx tube 2-10 mm. long, the 4 lobes united and turned to one side; petals 4, not clawed, 1-4 cm. long, pale pink to rose-purple, with carmine spots in the center, obovate to rounded; style 4-parted, the stigmas 1.5-5 mm. long, yellow, linear to oval; stamens 8, of two lengths, shorter than the style; ovary inferior, 4-celled. Fruit: Capsule 4-celled, 1.5-4.5 cm. long, beakless or with a beak several mm. long, straight or curved, linear.
June to August
West of the Cascades, occasional from Vancouver Island south to California, where more common.
Dry, open to wooded areas, at low elevations.
Indigenous Californians sowed Clarkia species and gathered the seeds to grind for food.
Sow seeds after last frost in cold-winter zones. Where winters are milder, sow seeds late summer through fall. Sow seeds in situ in spring or fall in vented containers in a coldframe, indoors before last frost, or direct sow after last frost. Plant plugs grown from seed. Germination is easy and it usually takes less than 90 days from seed to flowering plant. 95% germination occurs within the first two weeks after planting seed in a soil-less peat-based media, amended with micronutrients, slow-release fertilizer, and kept at 70 degree days and 50 degree nights. Prefers nutrient poor, well-drained, sandy loams. Soil should be moist until flowering starts, then it can be quite dry. Seed strains vary in color and habit; some are low and spreading, others tall and erect. Pinch out the central leader to encourage branching and heavy bloom. Do not thin seedlings as crowding encourages blooming. Full or partial sun.