Agoseris grandiflora

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Agoseris grandiflora, commonly known as bigflower agoseris, grassland agoseris, or sometimes California dandelion, is a flowering plant in the Asteracae family.


  • Agoseris laciniata
  • Stylopappus grandiflorus
  • Agoseris cinerea
  • Agoseris grandiflora (Nutt.) Greene var. intermedia
  • Agoseris grandiflora (Nutt.) Greene var. plebeia
  • Agoseris intermedia
  • Agoseris laciniata
  • Agoseris marshallii
  • Agoseris obtusifolia
  • Agoseris plebeia
  • Stylopappus grandiflorus Nutt.[1]
Agoseris grandiflora


  • Kingdom Plantae – Plants
  • Subkingdom Tracheobionta – Vascular plants
  • Superdivision Spermatophyta – Seed plants
  • Division Magnoliophyta – Flowering plants
  • Class Magnoliopsida – Dicotyledons
  • Subclass Asteridae
  • Order Asterales
  • Family Asteraceae – Aster family
  • Genus Agoseris Raf. – agoseris
  • Species Agoseris grandiflora (Nutt.) Greene – bigflower agoseris


Scapose, stout perennial, 2-7 dm. tall, somewhat hairy when young, the juice milky, with basal, oblanceolate to broadly linear pinnatifid leaves (10-25 cm. long and 1-3 cm. wide. Large flower head with many yellow flowers, involucre 1.5-4 cm. high, its outer bracts broad and short, the inner narrower and elongate; corollas all ligulate. Produces fruits with achene body 4-7 mm. long, tapering to a slender beak 2-4 times as long. [2]

Bloom Period

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Meadows and other open places in the lowlands and at moderate elevations in the mountains, often in dry areas.



Photo Gallery


Agoseris grandiflora

Abbreviation: AGGR

Seed sample from: 2010

Average Measurement: 5.2 x 0.7 x 0.7

Measurement Range: L: 4.6 - 6, W: 0.5 - 0.9, D: 0.5 - 0.9


Shape: Seeds tapering to a beak 2-3 times as long as the body of the seed.

Color: Seeds pale brown with white, glossy hilum.

Additional Structures: Pappus white, and downy.

Surface: Seed body deeply longitudinally grooved. Ridges are finely toothed. Seed slightly glossy.

Latitudinal Cross Section: elliptical Latitudinal AGGR.png

Longitudinal Cross Section: obovate Longitudinal AGGR.png

Basic Explanations and Assumptions:

The dimensions for the seeds are length x width x depth. The location of the hilum is used as the base of the seed, and the length is measured from hilum to the opposite apex. Where a style is present, the length is measured from the hilum to the bottom of the style. Width is measured at a right angle to the length at the widest part. Depth is measured at a right angle to the intersection of height and width lines.

Measurements included are the mean average for each measurement of ten separate seeds.

All measurements in millimeters unless otherwise noted.


  1. Washington Flora Checklist
  2. WTU Plants Profiles