ASTERACEAE (Compositae) Composite Family

Leaves: alternate or opposite, mostly simple, usually toothed or lobed, texture coarse, rough

Inflorescences: heads (capitula), each of which is surrounded by an involucre of bracts called phyllaries

involucre phyllary

Receptacle

Florets (flowers) of three general types: Disc florets – these are actinomorphic, often perfect Ray florets – these are zygomorphic, often pistillate or sterile Ligulate florets – these are zygomorphic, usually perfect

Disc florets Corolla of five fused petals Androecium of five stamens, these fused by their anthers, surrounding the style Disc florets Ovary inferior, gynoecium of two fused carpels

Calyx modified as a pappus, of hairs, bristles, etc.

Ligulate head and floret Ray floret Ligulate head and floret

Inflorescence structure: Heads radiate – both ray and disc florets Heads discoid – all disc florets Heads ligulate – all ligulate florets

An achene is a dry, indehiscent, one-seeded fruit . Fruit an achene

Economic Importance: food (sunflower seeds, artichokes, lettuce), ornamentals (zinnias, dahlias, cosmos, marigolds, chrysanthemums, sunflowers …), pyrethrum, echinacea

R A G W E D

Making Sense of Diversity: New England Tribes of the Aster Family

Cichoreae Chickory Tribe (non-native) Panicled hawkweed Tribe characters: Heads ligulate; sap milky

Cynareae Thistle Tribe Burdock (non-native) Spotted knapweed (non-native) Tribe characters: Heads discoid, involucre spiny

Eupatorieae Boneset Tribe White snakeroot Spotted Joe-pye weed Tribe characters: Heads discoid; leaves opposite or whorled

Inuleae, Everlasting Tribe Pearly everlasting Cudweed Tribe characters: Heads discoid, involucres papery, white

Heliantheae, Sunflower Tribe Cosmos (non-native) Burr marigold Woodland sunflower Tribe characters: Heads radiate, receptacle chaffy; lvs. opposite

Anthemideae, Chamomile Tribe Pineapple weed (non-native) Dog chamomile (non-native) Tansy (non-native) Tribe characters: Leaves finely dissected, aromatic

Senecioneae, Ragwort Tribe Coltsfoot (non-native) New England arnica Tribe characters: Heads radiate, phyllaries uniseriate; leaves alternate

Tribe characters: Heads radiate, phyllaries multiseriate; Astereae, Aster tribe Fleabane Blue-stemmed goldenrod New England aster Tribe characters: Heads radiate, phyllaries multiseriate; leaves alternate